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Search Topic:

Experimental realizations of routing or shuttling trapped ions in three dimensions in a quantum computer

Additional Context Provided:

So trapped ions are routed (moved around, or shuttled) to move specifically along rails or electrode directions of the electrodes that hold them in place. I want to find papers which talk about trapped ion quantum computing where the ions are routed in three dimensions.


After a deep search, Undermind suggests that very few papers exist on ArXiv which are precisely relevant to this search topic.

Deep search found 1 relevant papers. This is ~100% of all relevant papers that exist (see comprehensiveness analysis for details).

Highly Relevant References
 🟢 [1]
High-Fidelity Transport of Trapped-Ion Qubits in a Multi-Layer Array Deviprasath Palani, ..., Tobias Schaetz (2023)
arXiv:2305.05741 - 3 Citations

A variety of physical platforms are investigated for quantum control of many particles, and techniques are extended to access multiple dimensions. Here, we present our experimental study of shuttling single Mg$^+$ ions within a scalable trap-array architecture that contains up to thirteen trapping sites in a three-dimensional arrangement. We shuttle ions from a dedicated loading hub to multiple sites with a success rate of larger than $0.99999$. In a prototype application, we demonstrate the preservation of the coherence of superposition states of a hyperfine qubit during inter-site shuttling. Our findings highlight the potential of these techniques for use in future large-scale architectures.

The paper presents experimental data on the high-fidelity transport of Mg+ ions within a scalable 3D trap-array architecture. It demonstrates shuttling ions through a multi-layer setup with a high success rate, preserving coherence of qubit superposition states. This is directly related to the topic of interest as it showcases practical examples of 3D ion routing within a quantum computing architecture. The paper addresses scalability, shuttling efficiency, and the preservation of qubit states, which are all critical aspects of the topic.

Distantly Related References (missing key criteria)
 🔴 [2]
Controlling fast transport of cold trapped ions Andreas Walther, ..., Ulrich Poschinger (2012)
arXiv:1206.0364 - 181 Citations

We realize fast transport of ions in a segmented micro-structured Paul trap. The ion is shuttled over a distance of more than 10^4 times its groundstate wavefunction size during only 5 motional cycles of the trap (280 micro meter in 3.6 micro seconds). Starting from a ground-state-cooled ion, we find an optimized transport such that the energy increase is as low as 0.10 $\pm$ 0.01 motional quanta. In addition, we demonstrate that quantum information stored in a spin-motion entangled state is preserved throughout the transport. Shuttling operations are concatenated, as a proof-of-principle for the shuttling-based architecture to scalable ion trap quantum computing.

The paper describes the fast transport of ions in a segmented micro-structured Paul trap, demonstrating that optimized transport can be achieved with minimal energy increase and that quantum information is preserved during transport. While this shows advancements in shuttling ions and aligns with the broader topic of ion transport within quantum computers, it does not explicitly mention or discuss the three-dimensional control or routing of ions. The information given in the abstract and the selected parts of the paper mainly indicate operations likely performed in one or two dimensions (linear shuttling along a specific axis within the trap), which is quite common in trapping technologies. Given that the researcher is looking specifically for papers discussing 3D routing in quantum computers, this paper might not satisfy the criteria for 'three-dimensional' movement of ions.

 🔴 [3]
Programmable Quantum Simulations of Spin Systems with Trapped Ions C. Monroe, ..., N. Y. Yao (2019)
arXiv:1912.07845 - 299 Citations

Laser-cooled and trapped atomic ions form an ideal standard for the simulation of interacting quantum spin models. Effective spins are represented by appropriate internal energy levels within each ion, and the spins can be measured with near-perfect efficiency using state-dependent fluorescence techniques. By applying optical fields that exert optical dipole forces on the ions, their Coulomb interaction can be modulated to produce long-range and tunable spin-spin interactions that can be reconfigured by shaping the spectrum and pattern of the laser fields, in a prototypical example of a quantum simulator. Here we review the theoretical mapping of atomic ions to interacting spin systems, the preparation of complex equilibrium states, the study of dynamical processes in these many-body interacting quantum systems, and the use of this platform for optimization and other tasks. The use of such quantum simulators for studying spin models may inform our understanding of exotic quantum materials and shed light on the behavior of interacting quantum systems that cannot be modeled with conventional computers.

The provided paper describes a platform for quantum simulations of spin systems using trapped ions, focusing on the manipulation of effective spins and the study of quantum transport phenomena, among other topics. However, from the abstract and selected parts of the paper, there is no specific mention or discussion of the process for routing or shuttling trapped ions in three-dimensional configurations within a quantum computer. The text indicates ions are held in a linear Paul trap, which hints at a primarily one-dimensional configuration for the ion arrangement. While the discussion involves modifying interactions through laser fields, it does not describe the 3D shuttling of ions. Thus, this paper does not seem to be centered on the experimental realization of 3D ion routing or shuttling as required for the researcher's specific goal.

 🔴 [4]
Using Boolean Satisfiability for Exact Shuttling in Trapped-Ion Quantum Computers Daniel Schoenberger, ..., Robert Wille (2023)
arXiv:2311.03454 - 0 Citations

Trapped ions are a promising technology for building scalable quantum computers. Not only can they provide a high qubit quality, but they also enable modular architectures, referred to as Quantum Charge Coupled Device (QCCD) architecture. Within these devices, ions can be shuttled (moved) throughout the trap and through different dedicated zones, e.g., a memory zone for storage and a processing zone for the actual computation. However, this movement incurs a cost in terms of required time steps, which increases the probability of decoherence, and, thus, should be minimized. In this paper, we propose a formalization of the possible movements in ion traps via Boolean satisfiability. This formalization allows for determining the minimal number of time steps needed for a given quantum algorithm and device architecture, hence reducing the decoherence probability. An empirical evaluation confirms that -- using the proposed approach -- minimal results (i.e., the lower bound) can be determined for the first time. An open-source implementation of the proposed approach is publicly available at https://github.com/cda-tum/mqt-ion-shuttler.

The abstract of the paper and the terminology discusses the shuttling of ions within a trap and the difficulties associated with decoherence during such processes. The focus is on the formalization of the movements via Boolean satisfiability to minimize the movement-induced decoherence by streamlining the required time steps. Despite its talk of shuttling ions, the paper appears to center on the theoretical modeling of shuttling processes rather than reporting on hands-on experimental realizations of moving ions in 3D geometries. It doesn't explicitly mention the three-dimensional control of ions or provide details on experimental methodologies for 3D movement within a quantum computing environment.

 🔴 [5]
Bilayer crystals of trapped ions for quantum information processing Samarth Hawaldar, ..., Athreya Shankar (2023)
arXiv:2312.10681 - 0 Citations

Trapped ion systems are a leading platform for quantum information processing, but they are currently limited to 1D and 2D arrays, which imposes restrictions on both their scalability and their range of applications. Here, we propose a path to overcome this limitation by demonstrating that Penning traps can be used to realize remarkably clean bilayer crystals, wherein hundreds of ions self-organize into two well-defined layers. These bilayer crystals are made possible by the inclusion of an anharmonic trapping potential, which is readily implementable with current technology. We study the normal modes of this system and discover salient differences compared to the modes of single-plane crystals. The bilayer geometry and the unique properties of the normal modes open new opportunities in quantum information processing that are not straightforward in single-plane crystals. Furthermore, we illustrate that it may be possible to extend the ideas presented here to realize multilayer crystals with more than two layers. Our work increases the dimensionality of trapped ion systems by efficiently utilizing all three spatial dimensions and lays the foundation for a new generation of quantum information processing experiments with multilayer 3D crystals of trapped ions.

While the paper introduces the concept of bilayer and potentially trilayer crystals in ion traps, which increases the spatial dimensionality accessible for trapped ions in quantum systems, it does not specifically cover the experimental realization of 3D routing or shuttling of ions within a quantum computer. The focus is rather on the formation of multilayer ion crystals using Penning traps and the properties of these crystals. Although it lays groundwork for three-dimensional structures, it does not address the dynamic processes of moving ions along 3D paths as is required for routing or shuttling ions for quantum computing purposes.

 🔴 [6]
A two-dimensional architecture for fast large-scale trapped-ion quantum computing Y. -K. Wu, ..., L. -M. Duan (2020)
arXiv:2004.11608 - 2 Citations

Building blocks of quantum computers have been demonstrated in small to intermediate-scale systems. As one of the leading platforms, the trapped ion system has attracted wide attention. A significant challenge in this system is to combine fast high-fidelity gates with scalability and convenience in ion trap fabrication. Here we propose an architecture for large-scale quantum computing with a two-dimensional array of atomic ions trapped at such large distance which is convenient for ion-trap fabrication but usually believed to be unsuitable for quantum computing as the conventional gates would be too slow. Using gate operations far outside of the Lamb-Dicke region, we show that fast and robust entangling gates can be realized in any large ion arrays. The gate operations are intrinsically parallel and robust to thermal noise, which, together with their high speed and scalability of the proposed architecture, makes this approach an attractive one for large-scale quantum computing.

The paper provided, titled 'A two-dimensional architecture for fast large-scale trapped-ion quantum computing,' mainly discusses the challenges and a proposed architecture for scaling up trapped-ion quantum computers in two-dimensional arrays. While it does mention the challenges of scaling and theorizes on the potential of higher-dimensional system scalability, it does not specifically focus on actual experimental realizations of 3D ion routing or shuttling in a quantum computer. The topic of 3D shuttling is indeed relevant to the subject of the paper, but the paper's primary contribution seems to be in discussing two-dimensional arrays and potential benefits for quantum computing, rather than providing or discussing experiments that directly demonstrate routing ions in three dimensions.

 🔴 [7]
Closed-loop optimization of fast trapped-ion shuttling with sub-quanta excitation Jonathan D. Sterk, ..., Daniel Stick (2022)
arXiv:2201.07358 - 7 Citations

Shuttling ions at high speed and with low motional excitation is essential for realizing fast and high-fidelity algorithms in many trapped-ion based quantum computing architectures. Achieving such performance is challenging due to the sensitivity of an ion to electric fields and the unknown and imperfect environmental and control variables that create them. Here we implement a closed-loop optimization of the voltage waveforms that control the trajectory and axial frequency of an ion during transport in order to minimize the final motional excitation. The resulting waveforms realize fast round-trip transport of a trapped ion across multiple electrodes at speeds of $0.5$ electrodes/$\mu$s ($35 \text{m/s}$) with a maximum of $0.36\pm0.08$ quanta gain. This sub-quanta gain is independent of the phase of the secular motion at the distal location, obviating the need for an electric field impulse or time delay to eliminate the coherent motion

The paper describes the optimization of voltage waveforms to control the trajectory and axial frequency of an ion, focusing on rapid and low-excitation shuttling across multiple electrodes. However, it does not explicitly describe the 3D routing of ions; rather, the context seems primarily related to shuttling along a single dimension - across electrodes, which likely corresponds to a linear or planar arrangement instead of true 3D motion. Additionally, there is a mention of the Quantum Charge Coupled Device (QCCD) architecture, which includes 3D motion primitives but the paper does not detail these 3D motions. Moreover, the paper's emphasis on closed-loop optimization and sub-quanta excitation, while important for high-fidelity ion shuttling, does not squarely focus on the specifics of 3D spatial routing. Therefore, the paper's relevance to the exact topic seems peripheral rather than central.

 🔴 [8]
Efficient Qubit Routing for a Globally Connected Trapped Ion Quantum Computer Mark Webber, ..., Winfried K. Hensinger (2020)
arXiv:2002.12782 - 10 Citations

The cost of enabling connectivity in Noisy-Intermediate-Scale-Quantum devices is an important factor in determining computational power. We have created a qubit routing algorithm which enables efficient global connectivity in a previously proposed trapped ion quantum computing architecture. The routing algorithm was characterized by comparison against both a strict lower bound, and a positional swap based routing algorithm. We propose an error model which can be used to estimate the achievable circuit depth and quantum volume of the device as a function of experimental parameters. We use a new metric based on quantum volume, but with native two qubit gates, to assess the cost of connectivity relative to the upper bound of free, all to all connectivity. The metric was also used to assess a square grid superconducting device. We compare these two architectures and find that for the shuttling parameters used, the trapped ion design has a substantially lower cost associated with connectivity.

The provided paper appears to focus on the development of a qubit routing algorithm for trapped ion quantum computing architectures. While it does mention routing and the associated costs and efficiency issues, the selected parts of the paper do not explicitly indicate that it discusses experimental realizations of ion movement in three dimensions. The references cited in the paper could potentially contain relevant experimental details, but the abstract and selected parts are more about the theoretical and algorithmic framework for routing rather than specific experimental methodologies or implementations for 3D shuttling of ions.

 🔴 [9]
Tunable spin-spin interactions and entanglement of ions in separate wells Andrew C. Wilson, ..., David J. Wineland (2014)
arXiv:1407.5127 - 73 Citations

Quantum simulation - the use of one quantum system to simulate a less controllable one - may provide an understanding of the many quantum systems which cannot be modeled using classical computers. Impressive progress on control and manipulation has been achieved for various quantum systems, but one of the remaining challenges is the implementation of scalable devices. In this regard, individual ions trapped in separate tunable potential wells are promising. Here we implement the basic features of this approach and demonstrate deterministic tuning of the Coulomb interaction between two ions, independently controlling their local wells. The scheme is suitable for emulating a range of spin-spin interactions, but to characterize the performance of our setup we select one that entangles the internal states of the two ions with 0.82(1) fidelity. Extension of this building-block to a 2D-network, which ion-trap micro-fabrication processes enable, may provide a new quantum simulator architecture with broad flexibility in designing and scaling the arrangement of ions and their mutual interactions. To perform useful quantum simulations, including those of intriguing condensed-matter phenomena such as the fractional quantum Hall effect, an array of tens of ions might be sufficient.

This paper presents the tuning of interactions between trapped ions in separate potential wells and explores their entanglement, which is a significant aspect for quantum simulation and quantum information processing. However, it does not explicitly mention or focus on the routing or shuttling of ions in three dimensions within a quantum computer architecture. The work appears to be more related to the manipulation of spin-spin interactions and entanglement without specifically addressing the physical movement of ions along a 3D path. Thus, while the control of individual wells is an important aspect of the broader field of ion trap quantum computing, this paper does not seem to target the shuttling of ions in three dimensions specifically.

 🔴 [10]
Shuttling-Based Trapped-Ion Quantum Information Processing V. Kaushal, ..., U. Poschinger (2019)
arXiv:1912.04712 - 65 Citations

Moving trapped-ion qubits in a microstructured array of radiofrequency traps offers a route towards realizing scalable quantum processing nodes. Establishing such nodes, providing sufficient functionality to represent a building block for emerging quantum technologies, e.g. a quantum computer or quantum repeater, remains a formidable technological challenge. In this review, we present a holistic view on such an architecture, including the relevant components, their characterization and their impact on the overall system performance. We present a hardware architecture based on a uniform linear segmented multilayer trap, controlled by a custom-made fast multi-channel arbitrary waveform generator. The latter allows for conducting a set of different ion shuttling operations at sufficient speed and quality. We describe the relevant parameters and performance specifications for microstructured ion traps, waveform generators and additional circuitry, along with suitable measurement schemes to verify the system performance. Furthermore, a set of different basic shuttling operations for dynamic qubit register reconfiguration is described and characterized in detail.

The paper involves a review of shuttling-based trapped-ion quantum information processing, specifically within the context of microstructured arrays of radiofrequency traps. Though the abstract discusses the overall architecture of scalable quantum processing nodes using ion shuttling, it appears to concentrate more on the two-dimensional linear arrangement of traps and the shuttling operations within it. However, the latter part of the selected excerpt hints at the possibility of interconnections between nodes, either optically or possibly through the extraction and injection of ions from one linear trap to another. This could imply some degree of three-dimensionality in routing ions, even though it may not be the central focus of the paper. The focus on operational parameters, system performance, and methodology indicate that it does cover experimental aspects relevant to controlling ion motion, but the abstract does not explicitly confirm three-dimensional shuttling within the quantum computing architecture.

 🔴 [11]
Interference in a Prototype of a two-dimensional Ion Trap Array Quantum Simulator Frederick Hakelberg, ..., Tobias Schaetz (2018)
arXiv:1812.08552 - 17 Citations

Quantum mechanics dominates various effects in modern research from miniaturizing electronics, up to potentially ruling solid-state physics, quantum chemistry and biology. To study these effects experimental quantum systems may provide the only effective access. Seminal progress has been achieved in a variety of physical platforms, highlighted by recent applications. Atomic ions are known for their unique controllability and are identical by nature, as evidenced, e.g., by performing among the most precise atomic clocks and providing the basis for one-dimensional simulators. However, controllable, scalable systems of more than one dimension are required to address problems of interest and to reach beyond classical numerics with its powerful approximative methods. Here we show, tunable, coherent couplings and interference in a two-dimensional ion microtrap array, completing the toolbox for a reconfigurable quantum simulator. Previously, couplings and entangling interactions between sites in one-dimensional traps have been realized, while coupling remained elusive in microtrap approaches. Our architecture is based on well isolatable ions as identical quantum entities hovering above scalable CMOS chips. In contrast to other multi-dimensional approaches, it allows individual control in arbitrary, even non-periodic, lattice structures. Embedded control structures can exploit the long-range Coulomb interaction to configure synthetic, fully connected many-body systems to address multi-dimensional problems.

The paper's abstract and provided excerpt focus on a two-dimensional ion microtrap array and its use in quantum simulation, specifically highlighting the ability to control couplings and realize interference in 2D structures. Although the research contributes to advancing the control of ion traps in more than one dimension, it does not explicitly discuss the shuttling or routing of ions in three dimensions, which is the core interest of the topic at hand. Instead, the paper emphasizes couplings and the reconfigurability of the ion array in 2D.

 🔴 [12]
Demonstration of the trapped-ion quantum-CCD computer architecture J. M. Pino, ..., B. Neyenhuis (2020)
arXiv:2003.01293 - 78 Citations

The trapped-ion QCCD (quantum charge-coupled device) architecture proposal lays out a blueprint for a universal quantum computer. The design begins with electrodes patterned on a two-dimensional surface configured to trap multiple arrays of ions (or ion crystals). Communication within the ion crystal network allows for the machine to be scaled while keeping the number of ions in each crystal to a small number, thereby preserving the low error rates demonstrated in trapped-ion experiments. By proposing to communicate quantum information by moving the ions through space to interact with other distant ions, the architecture creates a quantum computer endowed with full-connectivity. However, engineering this fully-connected computer introduces a host of difficulties that have precluded the architecture from being fully realized in the twenty years since its proposal. Using a Honeywell cryogenic surface trap, we report on the integration of all necessary ingredients of the QCCD architecture into a programmable trapped-ion quantum computer. Using four and six qubit circuits, the system level performance of the processor is quantified by the fidelity of a teleported CNOT gate utilizing mid-circuit measurement and a quantum volume measurement of $2^6=64$. By demonstrating that the low error rates achievable in small ion crystals can be successfully integrated with a scalable trap design, parallel optical delivery, and fast ion transport, the QCCD architecture is shown to be a viable path toward large quantum computers. Atomic ions provide perfectly identical, high-fidelity qubits. Our work shows that the QCCD architecture built around these qubits will provide high performance quantum computers, likely enabling important near-term demonstrations such as quantum error correction and quantum advantage.

The paper details the QCCD (quantum charge-coupled device) architecture and outlines progress towards a scalable quantum computer using trapped ion technology. It demonstrates integrated system performance and fidelity for small ion crystals with rapid ion transport, but the abstract does not specifically mention routing or shuttling ions in three dimensions, focusing instead on two-dimensional patterns of electrodes. The information provided from the paper's selected parts does not suggest a strong focus on the 3D routing or control of ions, which is essential to the specific topic of interest. However, technologies that enable the QCCD architecture may have relevance to the broader field of trapped ion quantum computing.

 🔴 [13]
Controlling two-dimensional Coulomb crystals of more than 100 ions in a monolithic radio-frequency trap Dominik Kiesenhofer, ..., Christian F. Roos (2023)
arXiv:2302.00565 - 10 Citations

Linear strings of trapped atomic ions held in radio-frequency (rf) traps constitute one of the leading platforms for quantum simulation experiments, allowing for the investigation of interacting quantum matter. However, linear ion strings have drawbacks, such as the difficulty to scale beyond $\sim 50$ particles as well as the inability to naturally implement spin models with more than one spatial dimension. Here, we present experiments with planar Coulomb crystals of about 100 $^{40}$Ca$^+$ ions in a novel monolithic rf trap, laying the groundwork for quantum simulations of two-dimensional spin models with single-particle control. We characterize the trapping potential by analysis of crystal images and compare the observed crystal configurations with numerical simulations. We further demonstrate stable confinement of large crystals, free of structural configuration changes, and find that rf heating of the crystal is not an obstacle for future quantum simulation experiments. Finally, we prepare the out-of-plane motional modes of planar crystals consisting of up to 105 ions close to their ground state by electromagnetically-induced transparency cooling, an important prerequisite for implementing long-range entangling interactions.

The article is focused on controlling two-dimensional Coulomb crystals of ions in a novel monolithic rf trap and discusses the scaling up of trapped-ion experiments by considering a second spatial dimension. While the control of ions in two dimensions is closely related to the topic at hand, there is no specific discussion about moving ions in three dimensions as required by the researcher's question. The talk about routing or shuttling ions is also not evident; the focus appears to be on stable trapping and cooling. The trap discussed is a planar configuration, meaning that while it pushes the boundaries of what has been done with linear ion chains, it does not directly address full 3D control or the shuttling of ions in three dimensions.

 🔴 [14]
Quantum computing with trapped ions H. Haeffner, ..., R. Blatt (2008)
arXiv:0809.4368 - 615 Citations

Quantum computers hold the promise to solve certain computational task much more efficiently than classical computers. We review the recent experimental advancements towards a quantum computer with trapped ions. In particular, various implementations of qubits, quantum gates and some key experiments are discussed. Furthermore, we review some implementations of quantum algorithms such as a deterministic teleportation of quantum information and an error correction scheme.

The paper titled 'Quantum computing with trapped ions' by H. Haeffner, C. F. Roos, and R. Blatt primarily reviews the progress in quantum computing with trapped ions, highlighting qubits, quantum gates, and key experiments relevant to quantum computing. It mentions the advancement of shuttling ions in segmented traps and the prospect of scaling ion trap quantum computers, which implies that some degree of ion routing is discussed. However, the paper does not focus on or detail the three-dimensional aspect of ion movement or shuttling, which is a central point of the desired topic. It discusses challenges and broadly points to future directions but lacks specifics on 3D manipulation.

 🔴 [15]
Loading of a surface-electrode ion trap from a remote, precooled source Jeremy M. Sage, ..., John Chiaverini (2012)
arXiv:1205.6379 - 34 Citations

We demonstrate loading of ions into a surface-electrode trap (SET) from a remote, laser-cooled source of neutral atoms. We first cool and load $\sim$ $10^6$ neutral $^{88}$Sr atoms into a magneto-optical trap from an oven that has no line of sight with the SET. The cold atoms are then pushed with a resonant laser into the trap region where they are subsequently photoionized and trapped in an SET operated at a cryogenic temperature of 4.6 K. We present studies of the loading process and show that our technique achieves ion loading into a shallow (15 meV depth) trap at rates as high as 125 ions/s while drastically reducing the amount of metal deposition on the trap surface as compared with direct loading from a hot vapor. Furthermore, we note that due to multiple stages of isotopic filtering in our loading process, this technique has the potential for enhanced isotopic selectivity over other loading methods. Rapid loading from a clean, isotopically pure, and precooled source may enable scalable quantum information processing with trapped ions in large, low-depth surface trap arrays that are not amenable to loading from a hot atomic beam.

The paper discusses the loading of ions into a surface-electrode trap from a precooled neutral atom source, which addresses the initial placement of ions in a trap but not the subsequent manipulation and routing of these ions in three dimensions. While the introduction touches on the topic of scaling quantum information processing systems with trapped ions, it focuses more on the loading process, cleanliness, and isotopic selectivity rather than the 3D routing or shuttling of ions within a quantum processor. Therefore, the core content of the paper seems to lie outside the direct field of interest concerning the active manipulation of ion qubits in a 3D space.

 🔴 [16]
Design, fabrication and characterisation of a micro-fabricated double-junction segmented ion trap Chiara Decaroli, ..., Jonathan P. Home (2021)
arXiv:2103.05978 - 1 Citations

We describe the implementation of a three-dimensional Paul ion trap fabricated from a stack of precision-machined silica glass wafers, which incorporates a pair of junctions for 2-dimensional ion transport. The trap has 142 dedicated electrodes which can be used to define multiple potential wells in which strings of ions can be held. By supplying time-varying potentials, this also allows for transport and re-configuration of ion strings. We describe the design, simulation, fabrication and packaging of the trap, including explorations of different parameter regimes and possible optimizations and design choices. We give results of initial testing of the trap, including measurements of heating rates and junction transport.

This paper discusses the design and implementation of a 3D Paul ion trap that supports two-dimensional ion transport, which is essential for reconfiguring ion chains within a quantum computer. The double-junction segmented ion trap mentioned is critical for shuttling ions between different trapping zones and aligns with the aspect of 3D routing in a quantum computing system. However, it emphasizes 2D ion transport despite using a 3D electrode structure. The authors explore the challenges and solutions related to transport through junctions, which are directly relevant to the topic but do not fully cover the 3D aspect required by the researcher. Additionally, initial testing results like heating rates and junction transport are provided, which are important for understanding the characteristics of the ion trap in practice.

 🔴 [17]
Bright Source of Cold Ions for Surface-Electrode Traps Marko Cetina, ..., Vladan Vuletic (2007)
arXiv:physics/0702025 - 56 Citations

We produce large numbers of low-energy ions by photoionization of laser-cooled atoms inside a surface-electrode-based Paul trap. The isotope-selective trap loading rate of $4\times10^{5}$ Yb$^{+}$ ions/s exceeds that attained by photoionization (electron impact ionization) of an atomic beam by four (six) orders of magnitude. Traps as shallow as 0.13 eV are easily loaded with this technique. The ions are confined in the same spatial region as the laser-cooled atoms, which will allow the experimental investigation of interactions between cold ions and cold atoms or Bose-Einstein condensates.

This paper discusses the production of cold ions and their confinement using surface-electrode-based Paul traps. Although it mentions the ability of surface-electrode traps to create confining potentials above the surface and suggests the potential for real-time control over ion position in all directions, the paper does not provide detailed experimental results or techniques regarding the shuttling of ions in three dimensions. The focus seems to be more on the production and initial trapping of ions rather than on their subsequent routing within a quantum computing framework.

 🔴 [18]
From Quantum Optics to Quantum Technologies Dan Browne, ..., M. S. Kim (2017)
arXiv:1707.02925 - 37 Citations

Quantum optics is the study of the intrinsically quantum properties of light. During the second part of the 20th century experimental and theoretical progress developed together; nowadays quantum optics provides a testbed of many fundamental aspects of quantum mechanics such as coherence and quantum entanglement. Quantum optics helped trigger, both directly and indirectly, the birth of quantum technologies, whose aim is to harness non-classical quantum effects in applications from quantum key distribution to quantum computing. Quantum light remains at the heart of many of the most promising and potentially transformative quantum technologies. In this review, we celebrate the work of Sir Peter Knight and present an overview of the development of quantum optics and its impact on quantum technologies research. We describe the core theoretical tools developed to express and study the quantum properties of light, the key experimental approaches used to control, manipulate and measure such properties and their application in quantum simulation, and quantum computing.

The selected parts of the paper mention ion trap quantum computing and the implementation of qubit gates using trapped ions, discussing the indirect coupling of ions through collective modes. However, there is no explicit mention or focus on the experimental realizations of routing or shuttling trapped ions in three-dimensional structures. It seems the paper is more concerned with the theoretical underpinnings and techniques of ion trap quantum computing rather than the specifics of 3D ion movement and manipulation. Therefore, the article does not directly address the core topic of 3D routing or shuttling of trapped ions within quantum computer hardware.

 🔴 [19]
Unit cell of a Penning micro-trap quantum processor Shreyans Jain, ..., Jonathan Home (2023)
arXiv:2308.07672 - 0 Citations

Trapped ions in radio-frequency traps are among the leading approaches for realizing quantum computers, due to high-fidelity quantum gates and long coherence times. However, the use of radio-frequencies presents a number of challenges to scaling, including requiring compatibility of chips with high voltages, managing power dissipation and restricting transport and placement of ions. By replacing the radio-frequency field with a 3 T magnetic field, we here realize a micro-fabricated Penning ion trap which removes these restrictions. We demonstrate full quantum control of an ion in this setting, as well as the ability to transport the ion arbitrarily in the trapping plane above the chip. This unique feature of the Penning micro-trap approach opens up a modification of the Quantum CCD architecture with improved connectivity and flexibility, facilitating the realization of large-scale trapped-ion quantum computing, quantum simulation and quantum sensing.

The paper demonstrates control of ions in a Penning micro-trap, with transport capabilities within the trap plane, which relates to 2D motion rather than the 3D control the searched topic specifies. Although the technology presented opens possibilities for improved connectivity and 3D transport potential in quantum computing, the paper focuses primarily on advancements in 2D (x-z plane) ion transport and quantum control using a Penning trap, rather than 3D shuttling. The article showcases important developments in trapped ion technology and quantum control that could be foundational for eventual 3D control, but it does not specifically address the routing or shuttling of ions in three dimensions as described in the searched topic.

 🔴 [20]
T-junction ion trap array for two-dimensional ion shuttling, storage and manipulation W. K. Hensinger, ..., C. Monroe (2005)
arXiv:quant-ph/0508097 - 212 Citations

We demonstrate a two-dimensional 11-zone ion trap array, where individual laser-cooled atomic ions are stored, separated, shuttled, and swapped. The trap geometry consists of two linear rf ion trap sections that are joined at a 90 degree angle to form a T-shaped structure. We shuttle a single ion around the corners of the T-junction and swap the positions of two crystallized ions using voltage sequences designed to accommodate the nontrivial electrical potential near the junction. Full two-dimensional control of multiple ions demonstrated in this system may be crucial for the realization of scalable ion trap quantum computation and the implementation of quantum networks.

The paper presents research focused on a two-dimensional ion trap array for the purpose of ion shuttling, manipulation, and storage. While it does demonstrate the control of ions in a planar T-junction arrangement, this is not the same as shuttling ions in three dimensions. The main focus is on a two-dimensional control which is distinct from the specific topic of interest which is shuttling in three dimensions. Although the techniques and understanding from 2D control may have relevance, this paper does not appear to directly address the intricacies of 3D ion manipulation.

 🔴 [21]
Scalable multilayer architecture of assembled single-atom qubit arrays in a three-dimensional Talbot tweezer lattice Malte Schlosser, ..., Gerhard Birkl (2019)
arXiv:1902.05424 - 8 Citations

We report on the realization of a novel platform for the creation of large-scale 3D multilayer configurations of planar arrays of individual neutral-atom qubits: a microlens-generated Talbot tweezer lattice that extends 2D tweezer arrays to the third dimension at no additional costs. We demonstrate the trapping and imaging of rubidium atoms in integer and fractional Talbot planes and the assembly of defect-free atom arrays in different layers. The Talbot self-imaging effect for microlens arrays constitutes a structurally robust and wavelength-universal method for the realization of 3D atom arrays with beneficial scaling properties. With more than 750 qubit sites per 2D layer, these scaling properties imply that 10000 qubit sites are already accessible in 3D in our current implementation. The trap topology and functionality are configurable in the micrometer regime. We use this to generate interleaved lattices with dynamic position control and parallelized sublattice addressing of spin states for immediate application in quantum science and technology.

This paper describes the use of Talbot tweezer lattices for trapping and manipulating neutral atoms, not ions, in 3D structures for large-scale quantum computing. Although the platform demonstrates scalability, dynamic position control, and a multilayer architecture, the focused particles are neutral atoms rather than ions. Therefore, the technology and methodology, while related to quantum control and manipulation, do not directly correspond to the routing or shuttling of trapped ions in three dimensions as defined by the researcher's topic.

 🔴 [22]
On the Transport of Atomic Ions in Linear and Multidimensional Ion Trap Arrays D. Hucul, ..., C. Monroe (2007)
arXiv:quant-ph/0702175 - 72 Citations

Trapped atomic ions have become one of the most promising architectures for a quantum computer, and current effort is now devoted to the transport of trapped ions through complex segmented ion trap structures in order to scale up to much larger numbers of trapped ion qubits. This paper covers several important issues relevant to ion transport in any type of complex multidimensional rf (Paul) ion trap array. We develop a general theoretical framework for the application of time-dependent electric fields to shuttle laser-cooled ions along any desired trajectory, and describe a method for determining the effect of arbitrary shuttling schedules on the quantum state of trapped ion motion. In addition to the general case of linear shuttling over short distances, we introduce issues particular to the shuttling through multidimensional junctions, which are required for the arbitrary control of the positions of large arrays of trapped ions. This includes the transport of ions around a corner, through a cross or T junction, and the swapping of positions of multiple ions in a laser-cooled crystal. Where possible, we make connections to recent experimental results in a multidimensional T junction trap, where arbitrary 2-dimensional transport was realized.

The paper primarily addresses the theoretical framework and methods associated with shuttling trapped ions within segmented ion trap structures, which directly relates to the control and manipulation of ions, a key aspect of the topic in question. It describes procedures for shuttling ions linearly and through multidimensional junctions, including corners and T junctions, indicating a focus on two-dimensional control and manipulation. Although the abstract mentions that 2D transport was realized experimentally in a T junction trap, the paper does not provide explicit details on three-dimensional (3D) shuttling of ions within a quantum computer. Instead, it seems focused on two-dimensional issues and the theoretical understanding necessary for scaling up trapped ion architectures. Thus, the paper is relevant to the broader field of ion shuttling within quantum computers but does not specifically describe experimental realizations in three dimensions.

 🔴 [23]
Arbitrary Waveform Generator for Quantum Information Processing with Trapped Ions R. Bowler, ..., J. Amini (2013)
arXiv:1301.2543 - 45 Citations

Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logic pulses. The generator is based on a field-programmable gate array controlled ensemble of 16-bit digital-to-analog converters with an update frequency of 50 MHz and an output range of $\pm$10 V. The update rate of the waveform generator is much faster than relevant motional frequencies of the confined ions in our experiments, allowing diabatic control of the ion motion. Numerous pre-loaded sets of time-varying voltages can be selected with 40 ns latency conditioned on real-time signals. Here we describe the device and demonstrate some of its uses in ion-based quantum information experiments, including speed-up of ion transport and the shaping of laser and microwave pulses.

The abstract indicates that the paper is primarily focused on the development of a multi-channel arbitrary waveform generator designed for the dynamic control of the transport of ions in multi-electrode traps and for shaping quantum logic pulses. While it does talk about traps with multiple electrodes and demonstrates the application's utility in ion-based quantum information experiments, it does not specifically mention the 3D routing of ions in the context of quantum computing. Instead, the paper emphasizes fast transport and ion control for logic operations, not necessarily routing in all three dimensions as conceived in the research query. While the information about ion motion control and waveform generation may be tangentially relevant to the researcher's interest in 3D routing of ions, the paper clearly does not focus on the three-dimensional aspect of transporting ions in a quantum computing environment.

 🔴 [24]
Trapped-Ion Quantum Computing: Progress and Challenges Colin D. Bruzewicz, ..., Jeremy M. Sage (2019)
arXiv:1904.04178 - 718 Citations

Trapped ions are among the most promising systems for practical quantum computing (QC). The basic requirements for universal QC have all been demonstrated with ions and quantum algorithms using few-ion-qubit systems have been implemented. We review the state of the field, covering the basics of how trapped ions are used for QC and their strengths and limitations as qubits. In addition, we discuss what is being done, and what may be required, to increase the scale of trapped ion quantum computers while mitigating decoherence and control errors. Finally, we explore the outlook for trapped-ion QC. In particular, we discuss near-term applications, considerations impacting the design of future systems of trapped ions, and experiments and demonstrations that may further inform these considerations.

The abstract of this paper provides an overview of trapped-ion quantum computing, discussing the general state of the field including basics of using trapped ions as qubits, their strengths and limitations, and general considerations for scaling up. It also compares the performance of trapped-ion systems with superconducting qubit systems. However, from the details provided, there is no specific mention of the routing or shuttling of ions in three dimensions, which is the core of the desired topic. Instead, it appears to discuss more general aspects of trapped-ion quantum computing without focusing on the three-dimensional movement of ions. The excerpt highlighted doesn't explore the specific three-dimensional shuttling processes in detail.

 🔴 [25]
Scalable Loading of a Two-Dimensional Trapped-Ion Array C. D. Bruzewicz, ..., J. M. Sage (2015)
arXiv:1511.03293 - 39 Citations

We describe rapid, random-access loading of a two-dimensional (2D) surface-electrode ion-trap array based on two crossed photo-ionization laser beams. With the use of a continuous flux of pre-cooled neutral atoms from a remotely-located source, we achieve loading of a single ion per site while maintaining long trap lifetimes and without disturbing the coherence of an ion quantum bit in an adjacent site. This demonstration satisfies all major criteria necessary for loading and reloading extensive 2D arrays, as will be required for large-scale quantum information processing. Moreover, the already high loading rate can be increased by loading ions in parallel with only a concomitant increase in photo-ionization laser power and no need for additional atomic flux.

The paper discusses a loading scheme for a two-dimensional surface-electrode ion-trap array and does not delve into the three-dimensional routing or shuttling of ions. Although it contributes to the broader field of ion trap quantum computing by addressing scalable loading of ions, it does not specifically cover the manipulation of ions in three dimensions as required by the researcher's topic of interest. The loading process and the maintenance of ion coherence are relevant points, but the lack of focus on explicit three-dimensional shuttling makes the paper ancillary to the main topic.

 🔴 [26]
Transport Implementation of the Bernstein-Vazirani Algorithm with Ion Qubits Spencer Fallek, ..., Jason Amini (2016)
arXiv:1603.05672 - 30 Citations

Using trapped ion quantum bits in a scalable microfabricated surface trap, we perform the Bernstein-Vazirani algorithm. Our architecture relies upon ion transport and can readily be expanded to larger systems. The algorithm is demonstrated using two- and three-ion chains. For three ions, an improvement is achieved compared to a classical system using the same number of oracle queries. For two ions and one query, we correctly determine an unknown bit string with probability 97.6(8)%. For three ions, we succeed with probability 80.9(3)%.

The abstract and the selected parts of the paper suggest that this work primarily deals with trapped ion qubits in a surface trap, which implies 2D manipulation. Although the researchers mention the general field of quantum algorithms as having been performed in 3D traps previously, they indicate that their own demonstration occurs in a planar trap. It revolves around microfabrication benefits and control methods for scalable architectures, but the routing or shuttling appears to occur in two dimensions rather than three. Thus, the article indeed covers trapped ion quantum computing but does not focus on the specific 3D routing or shuttling of ions.

 🔴 [27]
High fidelity transport of trapped-ion qubits through an X-junction trap array R. B. Blakestad, ..., D. J. Wineland (2009)
arXiv:0901.0533 - 145 Citations

We report reliable transport of 9Be+ ions through a 2-D trap array that includes a separate loading/reservoir zone and an "X-junction". During transport the ion's kinetic energy in its local well increases by only a few motional quanta and internal-state coherences are preserved. We also examine two sources of energy gain during transport: a particular radio-frequency (RF) noise heating mechanism and digital sampling noise. Such studies are important to achieve scaling in a trapped-ion quantum information processor.

While the paper presents important work on the transport of ions and addresses key aspects such as maintaining coherence and minimizing kinetic energy gain, it specifically refers to a 2-D trap array and the movement through an X-junction. This suggests that the motion of the ions is confined to a plane and does not involve true 3D routing. Since the colleague's interest is in the routing of ions in three dimensions, this paper, despite its relevance to ion shuttling, does not fully match the stringent criteria set forth.

 🔴 [28]
Architecting Noisy Intermediate-Scale Trapped Ion Quantum Computers Prakash Murali, ..., Margaret Martonosi (2020)
arXiv:2004.04706 - 41 Citations

Trapped ions (TI) are a leading candidate for building Noisy Intermediate-Scale Quantum (NISQ) hardware. TI qubits have fundamental advantages over other technologies such as superconducting qubits, including high qubit quality, coherence and connectivity. However, current TI systems are small in size, with 5-20 qubits and typically use a single trap architecture which has fundamental scalability limitations. To progress towards the next major milestone of 50-100 qubits, a modular architecture termed the Quantum Charge Coupled Device (QCCD) has been proposed. In a QCCD-based TI device, small traps are connected through ion shuttling. While the basic hardware components for such devices have been demonstrated, building a 50-100 qubit system is challenging because of a wide range of design possibilities for trap sizing, communication topology and gate implementations and the need to match diverse application resource requirements. Towards realizing QCCD systems with 50-100 qubits, we perform an extensive architectural study evaluating the key design choices of trap sizing, communication topology and operation implementation methods. We built a design toolflow which takes a QCCD architecture's parameters as input, along with a set of applications and realistic hardware performance models. Our toolflow maps the applications onto the target device and simulates their execution to compute metrics such as application run time, reliability and device noise rates. Using six applications and several hardware design points, we show that trap sizing and communication topology choices can impact application reliability by up to three orders of magnitude. Microarchitectural gate implementation choices influence reliability by another order of magnitude. From these studies, we provide concrete recommendations to tune these choices to achieve highly reliable and performant application executions.

Although the paper delves into the architecture of modular trapped ion quantum computing systems and studies key design choices related to trap size, communication topology, and gate implementations, the focus seems to be largely on a higher-level system design and simulation of application performance within the Quantum Charge Coupled Device (QCCD) framework. The information from the selected parts of the paper indicates that shuttling is indeed discussed in the context of moving ions between traps to enable communication and gate operations across a modular system. However, the specific aspect of three-dimensional (3D) routing or shuttling is not emphasized or detailed. It appears that shuttling is treated as a more generalized concept, possibly within a planar rather than a truly 3D space, typical of QCCD implementations.

 🔴 [29]
High-fidelity quantum logic gates using trapped-ion hyperfine qubits C. J. Ballance, ..., D. M. Lucas (2015)
arXiv:1512.04600 - 458 Citations

We demonstrate laser-driven two-qubit and single-qubit logic gates with fidelities 99.9(1)% and 99.9934(3)% respectively, significantly above the approximately 99% minimum threshold level required for fault-tolerant quantum computation, using qubits stored in hyperfine ground states of calcium-43 ions held in a room-temperature trap. We study the speed/fidelity trade-off for the two-qubit gate, for gate times between 3.8$\mu$s and 520$\mu$s, and develop a theoretical error model which is consistent with the data and which allows us to identify the principal technical sources of infidelity.

The paper discusses the implementation and fidelity of laser-driven quantum logic gates using hyperfine qubits in trapped ions, which is an important aspect of trapped-ion quantum computing. However, the focus of the paper is specifically on the fidelity of quantum logic operations and the stabilization of internal quantum states. It does not provide details on the experimental realizations of shuttling or routing of trapped ions in three-dimensional configurations within a quantum computer. As such, while the hyperfine qubit technology is relevant to the field, this paper does not seem to address the physical movement or transportation of ions in three dimensions, which is the core element of the desired topic.

 🔴 [30]
Integrated optical multi-ion quantum logic Karan K. Mehta, ..., Jonathan P. Home (2020)
arXiv:2002.02258 - 145 Citations

Practical and useful quantum information processing (QIP) requires significant improvements with respect to current systems, both in error rates of basic operations and in scale. Individual trapped-ion qubits' fundamental qualities are promising for long-term systems, but the optics involved in their precise control are a barrier to scaling. Planar-fabricated optics integrated within ion trap devices can make such systems simultaneously more robust and parallelizable, as suggested by previous work with single ions. Here we use scalable optics co-fabricated with a surface-electrode ion trap to achieve high-fidelity multi-ion quantum logic gates, often the limiting elements in building up the precise, large-scale entanglement essential to quantum computation. Light is efficiently delivered to a trap chip in a cryogenic environment via direct fibre coupling on multiple channels, eliminating the need for beam alignment into vacuum systems and cryostats and lending robustness to vibrations and beam pointing drifts. This allows us to perform ground-state laser cooling of ion motion, and to implement gates generating two-ion entangled states with fidelities $>99.3(2)\%$. This work demonstrates hardware that reduces noise and drifts in sensitive quantum logic, and simultaneously offers a route to practical parallelization for high-fidelity quantum processors. Similar devices may also find applications in neutral atom and ion-based quantum-sensing and timekeeping.

Although the selected paper describes advancements in the integration of planar optical components into ion traps and high-fidelity multi-ion quantum logic gates, it does not explicitly cover the experimental routing or shuttling of ions in three dimensions. The work is highly relevant to the field of trapped ion quantum computing in terms of scalability and error mitigation but seems to focus on the integration of optics and robustness against environmental instabilities rather than three-dimensional motion control of the ions within the trap. There is no specific mention in the abstract or selected parts of the paper of the three-dimensional shuttling of ions.

 🔴 [31]
Two-dimensional linear trap array for quantum information processing Philip C. Holz, ..., Rainer Blatt (2020)
arXiv:2003.08085 - 0 Citations

We present an ion-lattice quantum processor based on a two-dimensional arrangement of linear surface traps. Our design features a tunable coupling between ions in adjacent lattice sites and a configurable ion-lattice connectivity, allowing one, e.g., to realize rectangular and triangular lattices with the same trap chip. We present detailed trap simulations of a simplest-instance ion array with $2\times9$ trapping sites and report on the fabrication of a prototype device in an industrial facility. The design and the employed fabrication processes are scalable to larger array sizes. We demonstrate trapping of ions in rectangular and triangular lattices and demonstrate transport of a $2\times2$ ion-lattice over one lattice period.

The abstract describes a two-dimensional ion-lattice quantum processor and focuses primarily on a 2D arrangement of linear surface traps. It discusses tunable coupling, configurable connectivity, and transport over a lattice, but all within two dimensions. The introduction elaborates on scaling up the number of qubits and the QCCD architecture, which involves ion shuttling. However, it only mentions 2D ion lattices and microfabricated arrays for these purposes. No explicit mention of 3D ion routing or shuttling is made in the abstract or the introduction, which suggests that the paper does not cover experimental realizations of 3D shuttling.

 🔴 [32]
Novel Ion Trap Junction Design for Transporting Qubits in a 2D Array Gavin N. Nop, ..., Durga Paudyal (2023)
arXiv:2310.07195 - 0 Citations

Junctions are fundamental elements that support qubit locomotion in two-dimensional ion trap arrays and enhance connectivity in emerging trapped-ion quantum computers. In surface ion traps they have typically been implemented by shaping radio frequency (RF) electrodes in a single plane to minimize the disturbance to the pseudopotential. However, this method introduces issues related to RF lead routing that can increase power dissipation and the likelihood of voltage breakdown. Here, we propose and simulate a novel two-layer junction design incorporating two perpendicularly rotoreflected linear ion traps. The traps are vertically separated, and create a trapping potential between their respective planes. The orthogonal orientation of the RF electrodes of each trap relative to the other provides perpendicular axes of confinement that can be used to realize transport in two dimensions. While this design introduces manufacturing and operating challenges, as now two separate structures have to be precisely positioned relative to each other in the vertical direction and optical access from the top is obscured, it obviates the need to route RF leads below the top surface of the trap and eliminates the pseudopotential bumps that occur in typical junctions. In this paper the stability of idealized ion transfer in the new configuration is demonstrated, both by solving the Mathieu equation analytically to identify the stable regions and by numerically modeling ion dynamics. Our novel junction layout enhances the flexibility of microfabricated ion trap control to enable large-scale trapped-ion quantum computing.

The abstract discusses a two-layer junction design for transporting ions within a 2D array. Although the paper mentions a novel design that deals with issues in 2D transport and provides potential enhancements for large-scale computing, it does not specifically address the transport of ions in three dimensions, which is the core interest of your colleague. Moreover, the paper primarily focuses on 2D connectivity challenges and solutions for ion traps. The Figure and Methods sections you provided concentrate on the design, stability analysis, and challenges associated with a new ion trap junction that operates within two dimensions. The lack of discussion about 3D shuttling of ions suggests the paper's contributions do not directly align with experimental realizations of routing or shuttling trapped ions in three dimensions.

 🔴 [33]
Blueprint for a microwave trapped-ion quantum computer B. Lekitsch, ..., W. K. Hensinger (2015)
arXiv:1508.00420 - 239 Citations

The availability of a universal quantum computer will have fundamental impact on a vast number of research fields and society as a whole. An increasingly large scientific and industrial community is working towards the realization of such a device. An arbitrarily large quantum computer is best constructed using a modular approach. We present a blueprint for a trapped-ion based scalable quantum computer module which makes it possible to create a scalable quantum computer architecture based on long-wavelength radiation quantum gates. The modules control all operations as stand-alone units, are constructed using silicon microfabrication techniques and they are within reach of current technology. To perform the required quantum computations, the modules make use of long-wavelength-radiation based quantum gate technology. To scale this microwave quantum computer architecture to an arbitrary size we present a fully scalable design that makes use of ion transport between different modules, thereby allowing arbitrarily many modules to be connected to construct a large-scale device. A high-error-threshold surface error correction code can be implemented in the proposed architecture to execute fault-tolerant operations. With only minor adjustments the proposed modules are also suitable for alternative trapped-ion quantum computer architectures, such as schemes using photonic interconnects.

The abstract provides an overview of a blueprint for a microwave trapped-ion quantum computer, emphasizing a modular approach, silicon microfabrication techniques, and the use of long-wavelength based quantum gate technology. While it mentions ion transport between modules, which is essential for scalability, there is no specific mention of 3D routing or shuttling within the abstract. The cited references within selected parts of the paper do point to literature on ion transport and coherent diabatic ion transport, but these references do not explicitly indicate that the motion occurs in three dimensions; instead, they may refer to 1D or 2D transport which is more common in current designs. Thus, while the paper is likely relevant due to its focus on ion transport and modular architecture, there's insufficient evidence from the abstract and the provided extractions that it contains focused discussion on experimental 3D shuttling of ions.

 🔴 [34]
How to wire a 1000-qubit trapped ion quantum computer M. Malinowski, ..., C. J. Ballance (2023)
arXiv:2305.12773 - 1 Citations

One of the most formidable challenges of scaling up quantum computers is that of control signal delivery. Today's small-scale quantum computers typically connect each qubit to one or more separate external signal sources. This approach is not scalable due to the I/O limitations of the qubit chip, necessitating the integration of control electronics. However, it is no small feat to shrink control electronics into a small package that is compatible with qubit chip fabrication and operation constraints without sacrificing performance. This so-called "wiring challenge" is likely to impact the development of more powerful quantum computers even in the near term. In this paper, we address the wiring challenge of trapped-ion quantum computers. We describe a control architecture called WISE (Wiring using Integrated Switching Electronics), which significantly reduces the I/O requirements of ion trap quantum computing chips without compromising performance. Our method relies on judiciously integrating simple switching electronics into the ion trap chip - in a way that is compatible with its fabrication and operation constraints - while complex electronics remain external. To demonstrate its power, we describe how the WISE architecture can be used to operate a fully connected 1000-qubit trapped ion quantum computer using ~ 200 signal sources at a speed of ~ 40 - 2600 quantum gate layers per second.

The paper describes the WISE control architecture for trapped-ion quantum computers, focusing on how this architecture alleviates the wiring challenge and facilitates scalability. It mentions ion transport as a means to achieve flexible qubit routing and the method of transport-assisted gates, which is based on leveraging ion transport within a QCCD architecture. However, the paper primarily seems to deal with signal delivery and control electronics integration rather than the specific experimental realizations of 3D ion shuttling. There is little direct reference to three-dimensional routing; it rather focuses on scalability and connectivity. Therefore, while the paper contributes to the broader subject of ion manipulation and quantum operation control in large-scale quantum computers, it does not explicitly focus on shuttling ions in three dimensions.

 🔴 [35]
Optimization and implementation of a surface-electrode ion trap junction Chi Zhang, ..., Jonathan P Home (2022)
arXiv:2201.12579 - 4 Citations

We describe the design of a surface-electrode ion trap junction, which is a key element for large-scale ion trap arrays. A bi-objective optimization method is used for designing the electrodes, which maintains the total pseudo-potential curvature while minimizing the axial pseudo-potential gradient along the ion transport path. To facilitate the laser beam delivery for parallel operations in multiple trap zones, we implemented integrated optics on each arm of this X-junction trap. The layout of the trap chip for commercial foundry fabrication is presented. This work suggests routes to improving ion trap junction performance in scalable implementations. Together with integrated optical addressing, this contributes to modular trapped-ion quantum computing in interconnected 2-dimensional arrays.

The paper focuses on the design and optimization of a surface-electrode ion trap junction, which is an essential component for scaling ion trap arrays. While they discuss improvements to junction performance and integrated optics for operations in a 2D trap array, there is no specific mention or focus on three-dimensional control and shuttling of ions. Instead, the paper seems to focus on 2D ion trap arrays and does not delve into the complexities of 3D ion routing, which is the crux of the desired topic. References cited in the paper mainly discuss theoretical aspects of ion traps, entanglement mechanics, and interconnected trap arrays, which again do not explicitly align with the practical realization of 3D shuttling of ions.

 🔴 [36]
Quantum Manipulation of Trapped Ions in Two Dimensional Coulomb Crystals D. Porras, ..., J. I. Cirac (2006)
arXiv:quant-ph/0601148 - 81 Citations

We show that a large number of ions stored in a Penning trap, and forming a 2D Coulomb crystal, provides an almost ideal system for scalable quantum computation and quantum simulation. In particular, the coupling of the internal states to the motion of the ions transverse to the crystal plane, allows one to implement two qubit quantum gates. We analyze in detail the decoherence induced by anharmonic couplings with in--plane hot vibrational modes, and show that very high gate fidelities can be achieved with current experimental set--ups.

The provided paper discusses the use of a Penning trap to store ions in a 2D Coulomb crystal, which is an arrangement distinctly not in three dimensions. It focuses on the coupling of internal states to the motion of the ions transverse to the crystal plane, effectively a two-dimensional process, and it addresses implementing two-qubit gates, as well as the related decoherence. While the paper does mention the interest in scalable quantum computation and provides some insight into ion traps as a system for many-qubit quantum processors, the main content primarily revolves around phenomena in two dimensions, not three. Furthermore, the paper does not address shuttling ions along pathways in three dimensions but rather is tailored to manipulation taking place in planar arrays.

 🔴 [37]
Improved high-fidelity transport of trapped-ion qubits through a multi-dimensional array R. B. Blakestad, ..., D. J. Wineland (2011)
arXiv:1106.5005 - 71 Citations

We have demonstrated transport of Be+ ions through a 2D Paul-trap array that incorporates an X-junction, while maintaining the ions near the motional ground-state of the confining potential well. We expand on the first report of the experiment [1], including a detailed discussion of how the transport potentials were calculated. Two main mechanisms that caused motional excitation during transport are explained, along with the methods used to mitigate such excitation. We reduced the motional excitation below the results in Ref. [1] by a factor of approximately 50. The effect of a mu-metal shield on qubit coherence is also reported. Finally, we examined a method for exchanging energy between multiple motional modes on the few-quanta level, which could be useful for cooling motional modes without directly accessing the modes with lasers. These results establish how trapped ions can be transported in a large-scale quantum processor with high fidelity.

The abstract and selected parts of the paper indicate that this study involves 2D transport of trapped ions using a Paul-trap array, which includes an X-junction. Although the research demonstrates improved fidelity in ion transportation and considers factors such as motional ground-state maintenance, trap potential calculation, motional excitation mitigation, and qubit coherence, there is no explicit mention of three-dimensional shuttling of ions. The emphasis on 2D arrays and the lack of specific discussion about 3D architecture serve as the basis for assessing relevance to the desired topic of 3D ion routing in a quantum computer.

 🔴 [38]
Quantum Circuit Compiler for a Shuttling-Based Trapped-Ion Quantum Computer Fabian Kreppel, ..., André Brinkmann (2022)
arXiv:2207.01964 - 5 Citations

Increasing capabilities of quantum computing hardware and the challenge to realize deep quantum circuits call for fully automated and efficient tools to compile quantum circuits. To express arbitrary circuits in a sequence of native gates pertaining to the specific quantum computer architecture is necessary to make algorithms portable across the landscape of quantum hardware providers. In this work, we present a compiler capable of transforming and optimizing a quantum circuit, targeting a shuttling-based trapped-ion quantum processor. It consists of custom algorithms set on top of the Cambridge Quantum Computer's quantum circuit framework Pytket. The performance is evaluated for a wide range of quantum circuits, showing that the gate counts can be reduced by a factor of up to 3.6 compared to standard Pytket and up to 2.2 compared to standard Qiskit compilation, while we achieve similar gate counts as compared to a Pytket extension targeting the AQT linear-static trapped ion addressing-based architecture.

The paper described focuses on a compiler developed for a shuttling-based trapped-ion quantum computer, which suggests relevance to the routing or shuttling of ions. The depicted architecture involves ions being stored and moved between segments using shuttling operations controlled by trap electrodes. However, despite the mention of shuttling operations and the management of ions within a register, the paper is primarily concerned with the compilation of quantum circuits for such a system and minimizing the number of shuttling operations by optimizing gate sequences. The paper does not detail the experimental 3D movement of ions, nor does it focus on the hardware aspects of ion routing in three dimensions. It seems more focused on the software side (compilation) rather than the physical realization of 3D shuttling.

 🔴 [39]
Multilayer ion trap technology for scalable quantum computing and quantum simulation Amado Bautista-Salvador, ..., Christian Ospelkaus (2018)
arXiv:1812.01829 - 19 Citations

We present a novel ion trap fabrication method enabling the realization of multilayer ion traps scalable to an in principle arbitrary number of metal-dielectric levels. We benchmark our method by fabricating a multilayer ion trap with integrated three-dimensional microwave circuitry. We demonstrate ion trapping and microwave control of the hyperfine states of a laser cooled $\,^{9}$Be$^{+}$ ion held at a distance of 35$\,\mu$m above the trap surface. This method can be used to implement large-scale ion trap arrays for scalable quantum information processing and quantum simulation.

The presented paper discusses the fabrication of multilayer ion traps with integrated 3D microwave circuitry, which is essential for the realization of scalable ion trap devices. However, the primary focus is on the fabrication method, materials, and compliance with the requirements for an ion trap capable of scaling. Although the technology could potentially contribute to 3D ion routing in quantum computers, the paper does not specifically report on experimental realizations of 3D routing or shuttling of ions within the traps themselves, which is crucial for understanding and validating the operational aspect of these systems as per the desired topic. The researcher might find the fabrication technology pertinent for background knowledge, but it may not fulfill the core requirement of experimental achievements in 3D ion movement.

 🔴 [40]
Single qubit manipulation in a microfabricated surface electrode ion trap Emily Mount, ..., Jungsang Kim (2013)
arXiv:1306.1269 - 46 Citations

We trap individual $^{171}$Yb$^+$ ions in a surface trap microfabricated on a silicon substrate, and demonstrate a complete set of high fidelity single qubit operations for the hyperfine qubit. Trapping times exceeding 20 minutes without laser cooling, and heating rates as low as 0.8(0.1) quanta/ms indicate stable trapping conditions in these microtraps. A coherence time of more than one second, high fidelity qubit state detection and single qubit rotations are demonstrated.

The paper discusses the trapping and manipulation of single $^{171}$Yb$^+$ ions using a microfabricated surface ion trap. The focus is on demonstrating a stable trapping and high fidelity single qubit operations using a planar electrode structure, which is inherently two-dimensional. While it mentions ion shuttling and control over ion motion, the specific requirement of three-dimensional routing is not explicitly addressed. There is no clear indication that the shuttling occurs in three dimensions or that the trap architecture provides a 3D ion routing capability as per your requirement. The paper seems to concentrate more on the manipulation of qubits and their properties than on the shuttling process in a three-dimensional space.

 🔴 [41]
Ion traps fabricated in a CMOS foundry K. K. Mehta, ..., J. Chiaverini (2014)
arXiv:1406.3643 - 48 Citations

We demonstrate trapping in a surface-electrode ion trap fabricated in a 90-nm CMOS (complementary metal-oxide-semiconductor) foundry process utilizing the top metal layer of the process for the trap electrodes. The process includes doped active regions and metal interconnect layers, allowing for co-fabrication of standard CMOS circuitry as well as devices for optical control and measurement. With one of the interconnect layers defining a ground plane between the trap electrode layer and the p-type doped silicon substrate, ion loading is robust and trapping is stable. We measure a motional heating rate comparable to those seen in surface-electrode traps of similar size. This is the first demonstration of scalable quantum computing hardware, in any modality, utilizing a commercial CMOS process, and it opens the door to integration and co-fabrication of electronics and photonics for large-scale quantum processing in trapped-ion arrays.

This paper introduces a surface-electrode ion trap using CMOS technology, and it shows the potential for scalability of such systems by integrating them with classical computing hardware and photonics. However, the abstract and selected parts of the paper do not describe or focus on the act of routing or shuttling ions in three dimensions, rather they emphasize the fabrication of the trap itself and its compatibility with CMOS processes. While this is foundational for the development of trapped ion quantum computers, it seems to lack specifics on 3D routing of ions, which is the prime focus of the desired topic.

 🔴 [42]
Reliable transport through a microfabricated X-junction surface-electrode ion trap Kenneth Wright, ..., Alexa W. Harter (2012)
arXiv:1210.3655 - 75 Citations

We report the design, fabrication, and characterization of a microfabricated surface-electrode ion trap that supports controlled transport through the two-dimensional intersection of linear trapping zones arranged in a ninety-degree cross. The trap is fabricated with very-large-scalable-integration (VLSI) techniques which are compatible with scaling to a larger quantum information processor. The shape of the radio-frequency (RF) electrodes is optimized with a genetic algorithm to minimize axial pseudopotential barriers and to minimize ion heating during transport. Seventy-eight independent DC control electrodes enable fine control of the trapping potentials. We demonstrate reliable ion transport between junction legs, trapping of ion chains with nearly-equal spacing in one of the trap's linear sections, and merging and splitting ions from these chains. Doppler-cooled ions survive more than 10^5 round-trip transits between junction legs without loss and more than sixty-five consecutive round trips without laser cooling.

The paper describes the design, fabrication, and testing of a microfabricated surface-electrode ion trap focused on 2D ion transport within a plane, as evidenced by the description of an 'X-junction' and a 'ninety-degree cross' indicating a two-dimensional intersection. Although it discusses advancements in ion trap technology and the ability to control ion transport, which is conceptually relevant, the explicit lack of three-dimensional control and routing suggests that this paper may not provide direct insights into the 3D routing in quantum computing environments that the researcher is interested in. The content is pertinent to ion shuttling but falls short in the dimensionality aspect.

 🔴 [43]
Transport of multispecies ion crystals through a junction in an RF Paul trap William Cody Burton, ..., Gabriel Price (2022)
arXiv:2206.11888 - 7 Citations

We report on the first demonstration of transport of a multispecies ion crystal through a junction in an RF Paul trap. The trap is a two-dimensional surface-electrode trap with an X junction and segmented control electrodes to which time-varying voltages are applied to control the shape and position of potential wells above the trap surface. We transport either a single $^{171}$Yb$^+$ ion or a crystal composed of a $^{138}$Ba$^+$ ion cotrapped with the $^{171}$Yb$^+$ ion to any port of the junction. We characterize the motional excitation by performing multiple round-trips through the junction and back to the initial well position without cooling. The final excitation is then measured using sideband asymmetry. For a single $^{171}$Yb$^+$ ion, transport with a $4\;\mathrm{m/s}$ average speed induces between $0.013\pm0.001$ and $0.014\pm0.001$ quanta of excitation per round trip, depending on the exit port. For a Ba-Yb crystal, transport at the same speed induces between $0.013\pm0.001$ and $0.030\pm0.002$ quanta per round trip of excitation to the axial center of mass mode. Excitation in the axial stretch mode ranges from $0.005\pm0.001$ to $0.021\pm0.001$ quanta per round trip.

The presented paper describes the transport of a multispecies ion crystal through a junction in a two-dimensional RF Paul trap, demonstrating maneuvering of ions in a controlled manner. The experiment is carried out in a surface-electrode trap which implies motion in the plane of the electrode surface and potential wells adjustable in two dimensions. Although they have accomplished intricate transport within this plane and measured motion-induced excitation, the work doesn't explicitly address the movement of ions in three dimensions as required by the topic in consideration. The transport, characterization, and error measurements are relevant to quantum computing, but the lack of explicit three-dimensional shuttling makes this paper not entirely on topic.

 🔴 [44]
Technologies for trapped-ion quantum information systems Amira M. Eltony, ..., Isaac L. Chuang (2015)
arXiv:1502.05739 - 19 Citations

Scaling-up from prototype systems to dense arrays of ions on chip, or vast networks of ions connected by photonic channels, will require developing entirely new technologies that combine miniaturized ion trapping systems with devices to capture, transmit and detect light, while refining how ions are confined and controlled. Building a cohesive ion system from such diverse parts involves many challenges, including navigating materials incompatibilities and undesired coupling between elements. Here, we review our recent efforts to create scalable ion systems incorporating unconventional materials such as graphene and indium tin oxide, integrating devices like optical fibers and mirrors, and exploring alternative ion loading and trapping techniques.

The abstract of the paper indicates that it is focused on the scaling-up of prototype systems to dense arrays of ions on chips and networks connected by photonic channels. It mentions incorporating miniaturized ion trapping systems and advances in technology that could help in the scalability and compactness of ion-based quantum information systems. However, there is no specific mention of three-dimensional routing or shuttling of ions, nor of experiments that demonstrate such techniques. The paper appears to be a general review of various technologies and possibilities in ion trap systems for quantum computing, but it lacks the specificity required by the topic at hand. The acknowledgments also suggest a broad focus on supportive technologies for scalable quantum systems, not the precise control of ion movement in three dimensions.

 🔴 [45]
Freely configurable quantum simulator based on a two-dimensional array of individually trapped ions Manuel Mielenz, ..., Tobias Schaetz (2015)
arXiv:1512.03559 - 5 Citations

A custom-built and precisely controlled quantum system may offer access to a fundamental understanding of another, less accessible system of interest. A universal quantum computer is currently out of reach, but an analog quantum simulator that makes the relevant observables, interactions, and states of a quantum model accessible could permit experimental insight into complex quantum dynamics that are intractable on conventional computers. Several platforms have been suggested and proof-of-principle experiments have been conducted. Here we characterise two-dimensional arrays of three ions trapped by radio-frequency fields in individually controlled harmonic wells forming equilateral triangles with side lengths 40 and 80 micrometer. In our approach, which is scalable to arbitrary two dimensional lattices, we demonstrate individual control of the electronic and motional degrees of freedom, preparation of a fiducial initial state with ion motion close to the ground state, as well as tuning of crucial couplings between ions within experimental sequences. Our work paves the way towards an analog quantum simulator of two-dimensional systems designed at will.

The paper discusses the characterization of two-dimensional arrays of individually trapped ions, their control, and manipulation. While it indicates an achievement towards scaling to a two-dimensional ion-trap lattice that could be used for simulation, there is no explicit mention of routing or shuttling ions in three dimensions. The main focus seems to be on the controlled interaction between ions in a 2D plane, preparation of initial states, and manipulation of couplings in a fixed array, rather than the dynamic three-dimensional transport of ions. Thus, this paper may not be entirely aligned with the desired topic of 3D routing or shuttling trapped ions within a quantum computer.

 🔴 [46]
Parallel Position-Controlled Composite Quantum Logic Gates with Trapped Ions Michael S. Gutierrez, ..., Helena Zhang (2017)
arXiv:1702.03568 - 1 Citations

We demonstrate parallel composite quantum logic gates with phases implemented locally through nanoscale movement of ions within a global laser beam of fixed pulse duration. We show that a simple four-pulse sequence suffices for constructing ideal arbitrary single-qubit rotations in the presence of large intensity inhomogeneities across the ion trap due to laser beam-pointing or beam-focusing. Using such sequences, we perform parallel arbitrary rotations on ions in two trapping zones separated by 700 $\mu$m with fidelities comparable to those of our standard laser-controlled gates. Our scheme improves on current transport or zone-dependent quantum gates to include phase modulation with local control of the ion's confinement potential. This enables a scalable implementation of an arbitrary number of parallel operations on densely packed qubits with a single laser modulator and beam path.

The paper presents methods for parallel quantum logic gates with trapped ions and focuses on local phase control rather than actual shuttling of ions along three-dimensional paths. The technique proposed involves nanoscale movement of ions to effect phase changes, which is a fundamentally different operation than routing ions in three dimensions. The emphasis is on reducing the need for moving ions over large distances and instead suggests displacing ions on small scales parallel to a laser beam. This suggests that actual 3D pathways for routing ions are not developed or explored in this work, which deviates from the desired focus on 3D ion shuttling within the quantum computing context.

 🔴 [47]
Coherent Diabatic Ion Transport and Separation in a Multi-Zone Trap Array R. Bowler, ..., D. J. Wineland (2012)
arXiv:1206.0780 - 185 Citations

We investigate the motional dynamics of single and multiple ions during transport between and separation into spatially distinct locations in a multi-zone linear Paul trap. A single 9Be+ ion in a 2 MHz harmonic well located in one zone was laser-cooled to near its ground state of motion and transported 370 micrometers by moving the well to another zone. This was accomplished in 8 microseconds, corresponding to 16 periods of oscillation. Starting from a state with n=0.1 quanta, during transport the ion was excited to a displaced coherent state with n=1.6 quanta but on completion was returned close to its motional ground state with n=0.2. Similar results were achieved for the transport of two ions. We also separated chains of up to 9 ions from one potential well to two distinct potential wells. With two ions this was accomplished in 55 microseconds, with final excitations of about 2 quanta for each ion. Fast coherent transport and separation can significantly reduce the time overhead in certain architectures for scalable quantum information processing with trapped ions.

While the paper discusses the transport and separation of ions in a multi-zone linear Paul trap and demonstrates advances in the speed and efficiency of ion shuttling that could benefit quantum computing architectures, the paper primarily focuses on one-dimensional motion. The linear Paul trap and the described transport between zones suggest motion along a single axis, which does not meet the three-dimensional criteria specified in the research topic. There is no indication in the abstract or the selected parts that three-dimensional routing of ions is addressed.

 🔴 [48]
Trapped Rydberg ions: a new platform for quantum information processing Arezoo Mokhberi, ..., Ferdinand Schmidt-Kaler (2020)
arXiv:2003.08891 - 6 Citations

In this chapter, we present an overview of experiments with trapped Rydberg ions and outline the advantages and challenges of developing applications of this new platform for quantum computing, sensing and simulation. Trapped Rydberg ions feature several important properties, unique in their combination: they are tightly bound in a harmonic potential of a Paul trap, in which their internal and external degrees of freedom can be controlled in a precise fashion. High fidelity state preparation of both internal and motional states of the ions has been demonstrated, and the internal states have been employed to store and manipulate qubit information. Furthermore, strong dipolar interactions can be realised between ions in Rydberg states and be explored for investigating correlated many-body systems. By laser coupling to Rydberg states, the polarisability of the ions can be both enhanced and tuned. This can be used to control the interactions with the trapping fields in a Paul trap as well as dipolar interactions between the ions. Thus, trapped Rydberg ions present an attractive alternative for fast entangling operations as compared to those mediated by normal modes of trapped ions, which are advantageous for a future quantum computer or a quantum simulator.

The provided paper discusses experiments with trapped Rydberg ions for quantum information processing, which is a broader topic than the specific focus on routing or shuttling ions in three dimensions. It emphasizes quantum gate operations, the fidelity of these operations, and the challenges of scaling up the architecture. There is mention of shuttling ions within a 'quantum-CCD' microfabricated array of traps for sequential gate operations, which suggests some relevance to routing in at least one or two dimensions. However, the paper does not explicitly address the three-dimensional aspect of shuttling or routing ions that is central to the desired research question. Moreover, Rydberg ions' specific properties like strong dipolar interactions and the control over internal and external degrees of freedom, while pertinent to quantum information processing, do not relate directly to the 3D routing or shuttling mechanisms required for the intended literature review.

 🔴 [49]
Surface-Electrode Architecture for Ion-Trap Quantum Information Processing J. Chiaverini, ..., D. J. Wineland (2005)
arXiv:quant-ph/0501147 - 258 Citations

We investigate a surface-mounted electrode geometry for miniature linear radio frequency Paul ion traps. The electrodes reside in a single plane on a substrate, and the pseudopotential minimum of the trap is located above the substrate at a distance on order of the electrodes' lateral extent or separation. This architecture provides the possibility to apply standard microfabrication principles to the construction of multiplexed ion traps, which may be of particular importance in light of recent proposals for large-scale quantum computation based on individual trapped ions.

Although the paper discusses a surface-mounted electrode geometry for ion traps and proposes a new architecture that may enable multiple ion trapping zones, the abstract and selected parts of the paper focus on a surface geometry—likely implying a mostly 2D electrodynamic control regime for ion manipulation. Given that the main interest is in 3D routing or shuttling of ions, while this research can be foundational for understanding ion trap arrays and their operation, it does not specifically address the shuttling of ions in three dimensions. Thus, from the given information, it appears that the paper mainly discusses concepts related to 2D trapping geometries and hence may not be fully aligned with the exact topic of 3D ion routing in a quantum computer.

 🔴 [50]
A Shuttle-Efficient Qubit Mapper for Trapped-Ion Quantum Computers Suryansh Upadhyay, ..., Swaroop Ghosh (2022)
arXiv:2204.03695 - 1 Citations

Trapped-ion (TI) quantum computer is one of the forerunner quantum technologies. However, TI systems can have a limited number of qubits in a single trap. Execution of meaningful quantum algorithms requires a multiple trap system. In such systems, the computation may frequently involve ions from two different traps for which the qubits must be co-located in the same trap, hence one of the ions needs to be shuttled (moved) between traps, increasing the vibrational energy, degrading fidelity, and increasing the program execution time. The choice of initial mapping influences the number of shuttles. The existing Greedy policy counts the number of gates occurring between each pair of qubits and assigns edge weight. The qubits with high edge weights are placed close to each other. However, it neglects the stage of the program at which the gate is occurring. Intuitively, the contribution of the late-occurring gates to the initial mapping reduces since the ions might have already shuttled to a different trap to satisfy other gate operations. In this paper, we target this gap and propose a new policy especially for programs with considerable depth and high number of qubits (valid for practical-scale quantum programs). Our policy is program adaptive and prioritizes the gates re-occurring at the initial stages of the program over late occurring gates. Our technique achieves an average reduction of 9% shuttles/program (with 21.3% at best) for 120 random circuits and enhances the program fidelity up to 3.3X (1.41X on average).

The paper 'A Shuttle-Efficient Qubit Mapper for Trapped-Ion Quantum Computers' addresses the concept of shuttling ions in trapped-ion quantum computers. However, the focus is on the initial qubit mapping to minimize the number of shuttles required between different traps in multi-trap systems and enhance the fidelity of quantum programs, rather than explicitly discussing three-dimensional ion routing. It appears to address the system-level optimization to reduce shuttling rather than the experimental realizations of the physical movement of ions in three dimensions. While understanding the shuttle optimization is relevant, it does not directly correspond to providing experimental details or methods for 3D routing of ions, which is of primary interest.

 🔴 [51]
Complete methods set for scalable ion trap quantum information processing J. P. Home, ..., D. J. Wineland (2009)
arXiv:0907.1865 - 231 Citations

Large-scale quantum information processors must be able to transport and maintain quantum information, and repeatedly perform logical operations. Here we demonstrate a combination of all the fundamental elements required to perform scalable quantum computing using qubits stored in the internal states of trapped atomic ions. We quantify the repeatability of a multi-qubit operation, observing no loss of performance despite qubit transport over macroscopic distances. Key to these results is the use of different pairs of beryllium ion hyperfine states for robust qubit storage, readout and gates, and simultaneous trapping of magnesium re-cooling ions along with the qubit ions.

The abstract and selected parts of this 2009 paper focus on crucial elements of quantum computing with trapped ions, including the repeatable multi-qubit operation and qubit transport over distances. The paper discusses the concept of moving ions within a multiple-zone trap array, which is related to routing. However, there is no specific mention of three-dimensional movement or control, which is a key aspect of the researcher's interest. While the paper appears to deal with the general architecture of a large-scale trapped-ion quantum processor and the concept of ion shuttling to different regions, the lack of explicit reference to three-dimensional control suggests that the paper may not exactly match the desired topic.

 🔴 [52]
Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation S. Charles Doret, ..., Alexa W. Harter (2012)
arXiv:1204.4147 - 70 Citations

Recent advances in quantum information processing with trapped ions have demonstrated the need for new ion trap architectures capable of holding and manipulating chains of many (>10) ions. Here we present the design and detailed characterization of a new linear trap, microfabricated with scalable complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited to this challenge. Forty-four individually controlled DC electrodes provide the many degrees of freedom required to construct anharmonic potential wells, shuttle ions, merge and split ion chains, precisely tune secular mode frequencies, and adjust the orientation of trap axes. Microfabricated capacitors on DC electrodes suppress radio-frequency pickup and excess micromotion, while a top-level ground layer simplifies modeling of electric fields and protects trap structures underneath. A localized aperture in the substrate provides access to the trapping region from an oven below, permitting deterministic loading of particular isotopic/elemental sequences via species-selective photoionization. The shapes of the aperture and radio-frequency electrodes are optimized to minimize perturbation of the trapping pseudopotential. Laboratory experiments verify simulated potentials and characterize trapping lifetimes, stray electric fields, and ion heating rates, while measurement and cancellation of spatially-varying stray electric fields permits the formation of nearly-equally spaced ion chains.

The provided paper discusses the design, characterization, and capability of a linear ion trap, manufactured using CMOS techniques suitable for quantum information processing with trapped ions. The trap architecture allows for anharmonic potential wells formation, ion shuttling, and chain manipulation, which are critical to the routing of ions in quantum computers. However, most discussions and technological advancements mentioned center around 2D trap architecture rather than 3D spatial ion routing. The focus seems to be on linear chains of ions and two-dimensional control without explicit mention of three-dimensional shuttling techniques. While the work is undoubtedly relevant to the field and could indirectly inform 3D shuttling through control techniques, precision tuning, and electrode design, it does not appear to target or demonstrate routing of ions in three dimensions specifically.

 🔴 [53]
Design, Fabrication, and Experimental Demonstration of Junction Surface Ion Traps D. L. Moehring, ..., M. G. Blain (2011)
arXiv:1105.1834 - 91 Citations

We present the design, fabrication, and experimental implementation of surface ion traps with Y-shaped junctions. The traps are designed to minimize the pseudopotential variations in the junction region at the symmetric intersection of three linear segments. We experimentally demonstrate robust linear and junction shuttling with greater than one million round-trip shuttles without ion loss. By minimizing the direct line of sight between trapped ions and dielectric surfaces, negligible day-to-day and trap-to-trap variations are observed. In addition to high-fidelity single-ion shuttling, multiple-ion chains survive splitting, ion-position swapping, and recombining routines. The development of two-dimensional trapping structures is an important milestone for ion-trap quantum computing and quantum simulations.

The presented paper focuses mainly on the design, fabrication, and experimental use of Y-shaped junction surface ion traps that are relevant for routing ions in a two-dimensional plane. While it does address high-fidelity shuttling and junction transport which are foundational for more complex ion manipulations, the paper does not appear to specifically investigate or demonstrate ion routing in three-dimensional configurations. The shuttling described is more pertinent to 2D junctions and linear motion, which is not exactly what the research query demands.

 🔴 [54]
Integrated optical addressing of an ion qubit Karan K. Mehta, ..., John Chiaverini (2015)
arXiv:1510.05618 - 169 Citations

The long coherence times and strong Coulomb interactions afforded by trapped ion qubits have enabled realizations of the necessary primitives for quantum information processing (QIP), and indeed the highest-fidelity quantum operations in any qubit to date. But while light delivery to each individual ion in a system is essential for general quantum manipulations and readout, experiments so far have employed optical systems cumbersome to scale to even a few tens of qubits. Here we demonstrate lithographically defined nanophotonic waveguide devices for light routing and ion addressing fully integrated within a surface-electrode ion trap chip. Ion qubits are addressed at multiple locations via focusing grating couplers emitting through openings in the trap electrodes to ions trapped 50 $\mu$m above the chip; using this light we perform quantum coherent operations on the optical qubit transition in individual $^{88}$Sr$^+$ ions. The grating focuses the beam to a diffraction-limited spot near the ion position with a 2 $\mu$m 1/$e^2$-radius along the trap axis, and we measure crosstalk errors between $10^{-2}$ and $4\times10^{-4}$ at distances 7.5-15 $\mu$m from the beam center. Owing to the scalability of the planar fabrication employed, together with the tight focusing and stable alignment afforded by optics integration within the trap chip, this approach presents a path to creating the optical systems required for large-scale trapped-ion QIP.

The provided abstract and selected parts of the paper suggest that the main focus of this study is the integration of nanophotonic waveguide devices for light routing and ion addressing within a surface-electrode ion trap chip. It demonstrates the delivery of focused light to perform quantum operations on individual ion qubits. However, there is no explicit mention of ion shuttling, which involves the physical movement of ions, nor is there a discussion of 3D trapping architectures for such shuttling. Therefore, while this research contributes to the general field of trapped-ion quantum computing, specifically addressing individual ions with an integrated optical system, it does not address the exact topic of interest of routing or shuttling trapped ions in three dimensions.

 🔴 [55]
Fabrication of Surface Ion Traps with Integrated Current Carrying Wires enabling High Magnetic Field Gradients Martin Siegele-Brown, ..., Winfried K. Hensinger (2022)
arXiv:2202.02313 - 2 Citations

A major challenge for quantum computers is the scalable simultaneous execution of quantum gates. One approach to address this in trapped ion quantum computers is the implementation of quantum gates based on static magnetic field gradients and global microwave fields. In this paper, we present the fabrication of surface ion traps with integrated copper current carrying wires embedded inside the substrate below the ion trap electrodes, capable of generating high magnetic field gradients. The copper layer's measured sheet resistance of 1.12 m$\Omega$/sq at room temperature is sufficiently low to incorporate complex designs, without excessive power dissipation at high currents causing a thermal runaway. At a temperature of 40 K the sheet resistance drops to 20.9 $\mu\Omega$/sq giving a lower limit for the residual resistance ratio of 100. Continuous currents of 13 A can be applied, resulting in a simulated magnetic field gradient of 144 T/m at the ion position, which is 125 $\mu$m from the trap surface for the particular anti-parallel wire pair in our design.

The paper presents fabrication methods for surface ion traps with integrated features that facilitate the creation of high magnetic field gradients, which indeed is quite relevant to ion manipulation in quantum computing. However, the primary focus appears to be on the development of the trap itself and its capacity for creating magnetic field gradients, rather than specifically on the three-dimensional routing or shuttling of trapped ions. While the technology may serve as a foundational component for 3D routing or shuttling, the paper does not directly address the specific process or experiments of moving ions in three dimensions within a quantum computing system.

 🔴 [56]
A trapped ion quantum computer with robust entangling gates and quantum coherent feedback Tom Manovitz, ..., Roee Ozeri (2021)
arXiv:2111.04155 - 11 Citations

Quantum computers are expected to achieve a significant speed-up over classical computers in solving a range of computational problems. Chains of ions held in a linear Paul trap are a promising platform for constructing such quantum computers, due to their long coherence times and high quality of control. Here we report on the construction of a small, five-qubit, universal quantum computer using $^{88}\text{Sr}^{+}$ ions in an RF trap. All basic operations, including initialization, quantum logic operations, and readout, are performed with high fidelity. Selective two-qubit and single-qubit gates, implemented using a narrow linewidth laser, comprise a universal gate set, allowing realization of any unitary on the quantum register. We review the main experimental tools, and describe in detail unique aspects of the computer: the use of robust entangling gates and the development of a quantum coherent feedback system through EMCCD camera acquisition. The latter is necessary for carrying out quantum error correction protocols in future experiments.

From the abstract and selected parts of the paper provided, this article mainly focuses on the construction and operation of a linear trapped ion quantum computer with 88Sr+ ions in an RF trap, describing basic operations and the implementation of robust entangling gates and quantum coherent feedback for error correction. It does mention shuttling ions but only as a general approach to scaling up trapped-ion quantum computers, citing other works. The specific topic of routing or shuttling trapped ions in three dimensions is not directly addressed, discussed, or appears to be the core focus of this paper.

 🔴 [57]
Large Scale Modular Quantum Computer Architecture with Atomic Memory and Photonic Interconnects C. Monroe, ..., J. Kim (2012)
arXiv:1208.0391 - 466 Citations

The practical construction of scalable quantum computer hardware capable of executing non-trivial quantum algorithms will require the juxtaposition of different types of quantum systems. We analyze a modular ion trap quantum computer architecture with a hierarchy of interactions that can scale to very large numbers of qubits. Local entangling quantum gates between qubit memories within a single register are accomplished using natural interactions between the qubits, and entanglement between separate registers is completed via a probabilistic photonic interface between qubits in different registers, even over large distances. We show that this architecture can be made fault-tolerant, and demonstrate its viability for fault-tolerant execution of modest size quantum circuits.

The abstract mentions a modular ion trap quantum computer architecture, implying some form of routing or shuttling, but it lacks specificity about three-dimensional shuttling. However, the selected parts of the paper suggest a focus on a two-dimensional surface trap architecture commonly associated with the QCCD approach. While the paper discusses advanced control of trapping potential to manipulate ion position and acknowledges limitations in scaling and distance, it does not specifically mention three-dimensional ion routing mechanisms, suggesting that the paper’s main focus may not align directly with experimental realizations of 3D ion shuttling within a quantum computer as specified by your colleague.

 🔴 [58]
High-fidelity preparation, gates, memory and readout of a trapped-ion quantum bit T. P. Harty, ..., D. M. Lucas (2014)
arXiv:1403.1524 - 431 Citations

We implement all single-qubit operations with fidelities significantly above the minimum threshold required for fault-tolerant quantum computing, using a trapped-ion qubit stored in hyperfine "atomic clock" states of $^{43}$Ca$^+$. We measure a combined qubit state preparation and single-shot readout fidelity of 99.93%, a memory coherence time of $T^*_2=50$ seconds, and an average single-qubit gate fidelity of 99.9999%. These results are achieved in a room-temperature microfabricated surface trap, without the use of magnetic field shielding or dynamic decoupling techniques to overcome technical noise.

The examined paper primarily discusses the achievement of high-fidelity single-qubit operations, state preparation, memory coherence, and readout in trapped-ion qubit systems, which are essential for the accuracy and feasibility of quantum computing. However, it is focused on operations within a microfabricated surface trap with a two-dimensional electrode layout, and there is no mention of three-dimensional routing or shuttling of ions. It appears that this paper does not address the specific requirement of '3D manipulation' as the trap described operates in a 2D layout and the paper does not discuss the mechanisms or experimental results of moving ions in three dimensions.

 🔴 [59]
Crosstalk Suppression for Fault-tolerant Quantum Error Correction with Trapped Ions Pedro Parrado-Rodríguez, ..., Markus Müller (2020)
arXiv:2012.11366 - 32 Citations

Physical qubits in experimental quantum information processors are inevitably exposed to different sources of noise and imperfections, which lead to errors that typically accumulate hindering our ability to perform long computations reliably. Progress towards scalable and robust quantum computation relies on exploiting quantum error correction (QEC) to actively battle these undesired effects. In this work, we present a comprehensive study of crosstalk errors in a quantum-computing architecture based on a single string of ions confined by a radio-frequency trap, and manipulated by individually-addressed laser beams. This type of errors affects spectator qubits that, ideally, should remain unaltered during the application of single- and two-qubit quantum gates addressed at a different set of active qubits. We microscopically model crosstalk errors from first principles and present a detailed study showing the importance of using a coherent vs incoherent error modelling and, moreover, discuss strategies to actively suppress this crosstalk at the gate level. Finally, we study the impact of residual crosstalk errors on the performance of fault-tolerant QEC numerically, identifying the experimental target values that need to be achieved in near-term trapped-ion experiments to reach the break-even point for beneficial QEC with low-distance topological codes.

The abstract and selected parts of the paper discuss advancements in quantum error correction, crosstalk errors, and the scalability of trapped-ion systems for quantum computing. Although it mentions a shuttling-based approach to scalability and briefly describes the shuttling of ions between different zones, the paper primarily focuses on single-string ion traps. The shuttling described does not emphasize or detail the three-dimensional routing aspect, which is at the core of the desired research topic. The approach taken by the researchers in the paper appears to be more in line with one-dimensional or two-dimensional manipulations rather than the specific interest in three-dimensional routing within quantum computers.

 🔴 [60]
Industrially Microfabricated Ion Trap with 1 eV Trap Depth S. Auchter, ..., J. Home (2022)
arXiv:2202.08244 - 12 Citations

Scaling trapped-ion quantum computing will require robust trapping of at least hundreds of ions over long periods, while increasing the complexity and functionality of the trap itself. Symmetric 3D structures enable high trap depth, but microfabrication techniques are generally better suited to planar structures that produce less ideal conditions for trapping. We present an ion trap fabricated on stacked 8-inch wafers in a large-scale MEMS microfabrication process that provides reproducible traps at a large volume. Electrodes are patterned on the surfaces of two opposing wafers bonded to a spacer, forming a 3D structure with 2.5 micrometer standard deviation in alignment across the stack. We implement a design achieving a trap depth of 1 eV for a calcium-40 ion held at 200 micrometers from either electrode plane. We characterize traps, achieving measurement agreement with simulations to within +/-5% for mode frequencies spanning 0.6--3.8 MHz, and evaluate stray electric field across multiple trapping sites. We measure motional heating rates over an extensive range of trap frequencies, and temperatures, observing 40 phonons/s at 1 MHz and 185 K. This fabrication method provides a highly scalable approach for producing a new generation of 3D ion traps.

While the paper discusses the development of microfabricated ion traps which are a crucial element in facilitating the routing or shuttling of ions, the main focus of the paper appears to be on the fabrication process and the quality of trapping rather than on the experimental realization of routing or shuttling the ions in three dimensions specifically. The reference to shuttling ions between zones using segmented electrodes suggests relevance to the topic, but there is no explicit indication that such shuttling occurs in three dimensions or that there is explicit experimental data on 3D routing within a quantum computer. The paper's contribution seems to be more towards scalable trap fabrication for potential future routing, rather than a direct demonstration of 3D ion movement.

 🔴 [61]
Engineering of Microfabricated Ion Traps and Integration of Advanced On-Chip Features Zak David Romaszko, ..., Winfried Karl Hensinger (2019)
arXiv:1908.00267 - 34 Citations

Trapped atomic ions are a proven and powerful tool for the fundamental research of quantum physics. They have emerged in recent years as one of the most promising candidates for several practical technologies including quantum computers, quantum simulators, atomic clocks, mass spectrometers and quantum sensors. Advanced fabrication techniques, taken from established and nascent disciplines, are being deployed to create novel, reliable devices with a view to large scale integration and commercial compatibility. This review will cover the fundamentals of ion trapping before proceeding with a discussion of the design of ion traps for the aforementioned applications. We will analyse current microfabrication techniques that are being utilised, as well as various considerations which motivate the choice of materials and processes. Finally, we discuss current efforts to include advanced, on-chip features into next generation ion traps.

The provided paper seems to focus primarily on the advancements of microfabricated ion traps, which are essential for complex designs in ion trapping. It discusses the design considerations and fabrication technologies for ion traps that can be used in quantum computing and other applications. Though the paper mentions 'junction shuttling' and two-dimensional grid or plane arrangements for ion traps, it seems to emphasize linear and 2D structures rather than explicit 3D control. The focus is more on fabrication and the integration of features on chip rather than the specific shuttling of ions in 3D space. The discussion of preserving quantum information during ion transport is relevant, but it does not provide a direct focus on the 3D aspect that is central to the researcher's query. Therefore, it seems the paper centers on foundational technologies and 2D ion routing rather than experimental realizations of 3D routing in a quantum computer.

 🔴 [62]
A compact ion-trap quantum computing demonstrator Ivan Pogorelov, ..., Thomas Monz (2021)
arXiv:2101.11390 - 145 Citations

Quantum information processing is steadily progressing from a purely academic discipline towards applications throughout science and industry. Transitioning from lab-based, proof-of-concept experiments to robust, integrated realizations of quantum information processing hardware is an important step in this process. However, the nature of traditional laboratory setups does not offer itself readily to scaling up system sizes or allow for applications outside of laboratory-grade environments. This transition requires overcoming challenges in engineering and integration without sacrificing the state-of-the-art performance of laboratory implementations. Here, we present a 19-inch rack quantum computing demonstrator based on $^{40}\textrm{Ca}^+$ optical qubits in a linear Paul trap to address many of these challenges. We outline the mechanical, optical, and electrical subsystems. Further, we describe the automation and remote access components of the quantum computing stack. We conclude by describing characterization measurements relevant to digital quantum computing including entangling operations mediated by the Molmer-Sorenson interaction. Using this setup we produce maximally-entangled Greenberger-Horne-Zeilinger states with up to 24 ions without the use of post-selection or error mitigation techniques; on par with well-established conventional laboratory setups.

The paper discusses a quantum computing demonstrator that employs a linear Paul trap to contain and manipulate calcium ions in a 19-inch rack setup. Key themes include the integration of mechanical, optical, and electrical subsystems, automation, and remote access components. While it addresses challenges in engineering and characterizes entangling operations within an ion trapping environment, the focus on a linear Paul trap indicates that routing or shuttling ions might be limited to one dimension, which is not the three-dimensional manipulation your colleague is interested in. Furthermore, the abstract does not explicitly mention three-dimensional routing or shuttling of ions, which suggests that the paper may not concentrate on this particular aspect of trapped ion quantum computing.

 🔴 [63]
High Fidelity Entangling Gates in a 3D Ion Crystal under Micromotion Y. -K. Wu, ..., L. -M. Duan (2020)
arXiv:2009.13007 - 0 Citations

Ion trap is one of the most promising candidates for quantum computing. Current schemes mainly focus on a linear chain of up to about one hundred ions in a Paul trap. To further scale up the qubit number, one possible direction is to use 2D or 3D ion crystals (Wigner crystals). In these systems, ions are generally subjected to large micromotion due to the strong fast-oscillating electric field, which can significantly influence the performance of entangling gates. In this work, we develop an efficient numerical method to design high-fidelity entangling gates in a general 3D ion crystal. We present numerical algorithms to solve the equilibrium configuration of the ions and their collective normal modes. We then give a mathematical description of the micromotion and use it to generalize the gate scheme for linear ion chains into a general 3D crystal. The involved time integral of highly oscillatory functions is expanded into a fast-converging series for accurate and efficient evaluation and optimization. As a numerical example, we show a high-fidelity entangling gate design between two ions in a 100-ion crystal, with a theoretical fidelity of 99.9\%.

While the paper discusses high-fidelity entangling gates for ions in a 3D crystal and related challenges such as micromotion, it does not focus on the experimental aspect of routing or shuttling trapped ions in three dimensions. The paper seems to concentrate more on theoretical and numerical methods pertaining to ion trap quantum computing scalability and quantum gate design in a 3D system. There is mention of the need for ion shuttling or photonic quantum networks for systems with a large number of qubits, but this is within a discussion context rather than a detailed description of actual 3D routing or shuttling. Therefore, it does not provide the experimental details that the specific research topic requires.

 🔴 [64]
Trapping Ions and Atoms Optically Tobias Schaetz (2021)
arXiv:2105.01155 - 38 Citations

Isolating neutral and charged particles from the environment is essential in precision experiments. For decades, this has been achieved by trapping ions with radio-frequency (rf) fields and neutral particles with optical fields. Recently, trapping of ions by interaction with light has been demonstrated. This might permit combining the advantages of optical trapping and ions. For example, by superimposing optical traps to investigate ensembles of ions and atoms in absence of any radiofrequency fields, as well as to benefit from the versatile and scalable trapping geometries featured by optical lattices. In particular, ions provide individual addressability, electronic and motional degrees of freedom that can be coherently controlled and detected via high fidelity, state-dependent operations. Their long-range Coulomb interaction is significantly larger compared to those of neutral atoms and molecules. This qualifies to study ultra-cold interaction and chemistry of trapped ions and atoms, as well as to provide a novel platform for higher-dimensional experimental quantum simulations. The aim of this topical review is to present the current state of the art and to discuss current challenges and the prospects of the emerging field.

The paper discusses the prospects of trapping ions optically and explores the potential benefits for quantum information processing (QIP) and analog quantum simulations (AQS). While it touches on the idea of using optical lattices for enhanced control and higher-dimensional geometries, it does not focus on the specific process of routing or shuttling ions in three dimensions within a quantum computer. Additionally, the paper seems to concentrate more on the trapping mechanisms using optical fields rather than the dynamic process of ion movement which is central to the routing or shuttling concept described by the researcher. Therefore, it may offer tangential insights rather than direct experimental methods or observations of 3D ion movement in a quantum computing setup.

 🔴 [65]
Co-Designing a Scalable Quantum Computer with Trapped Atomic Ions K. R. Brown, ..., C. Monroe (2016)
arXiv:1602.02840 - 206 Citations

The first generation of quantum computers are on the horizon, fabricated from quantum hardware platforms that may soon be able to tackle certain tasks that cannot be performed or modelled with conventional computers. These quantum devices will not likely be universal or fully programmable, but special-purpose processors whose hardware will be tightly co-designed with particular target applications. Trapped atomic ions are a leading platform for first generation quantum computers, but are also fundamentally scalable to more powerful general purpose devices in future generations. This is because trapped ion qubits are atomic clock standards that can be made identical to a part in 10^15, and their quantum circuit connectivity can be reconfigured through the use of external fields, without modifying the arrangement or architecture of the qubits themselves. In this article we show how a modular quantum computer of any size can be engineered from ion crystals, and how the wiring between ion trap qubits can be tailored to a variety of applications and quantum computing protocols.

The abstract indicates that the paper discusses the scalability of quantum computers using trapped atomic ions and the configurability of quantum circuit connectivity using external fields, without alterations to the qubits' spatial arrangement. While it touches on reconfiguring connections between qubit zones, which is pertinent to the idea of routing or shuttling ions, it does not specifically mention the experimental realization of three-dimensional motion of trapped ions within a quantum computer. The focus seems to be on a broader view of scalable ion trap quantum computing and the principles of co-designing hardware and applications, rather than on the details of 3D ion shuttling techniques.

 🔴 [66]
Controlling the transport of an ion: Classical and quantum mechanical solutions H. A. Fürst, ..., C. P. Koch (2013)
arXiv:1312.4156 - 41 Citations

We investigate the performance of different control techniques for ion transport in state-of-the-art segmented miniaturized ion traps. We employ numerical optimization of classical trajectories and quantum wavepacket propagation as well as analytical solutions derived from invariant based inverse engineering and geometric optimal control. We find that accurate shuttling can be performed with operation times below the trap oscillation period. The maximum speed is limited by the maximum acceleration that can be exerted on the ion. When using controls obtained from classical dynamics for wavepacket propagation, wavepacket squeezing is the only quantum effect that comes into play for a large range of trapping parameters. We show that this can be corrected by a compensating force derived from invariant based inverse engineering, without a significant increase in the operation time.

This paper primarily investigates the control of ion transport in miniaturized segmented ion traps, focusing on numerical and analytical methods for optimizing classical and quantum mechanical solutions. The selected parts of the paper discuss improving stability against uncertainties in transport time and the impact of anharmonic potential fluctuations on the trapped ion's wavepacket. However, there is no explicit mention of routing or shuttling ions in three dimensions nor is there indication of experimental realization within the specifically mentioned sections. The emphasis is on control techniques for accurate shuttling with considerations for quantum effects such as wavepacket squeezing, which is relevant to the quantum transport of ions in general but does not appear to address three-dimensional routing specifically.

 🔴 [67]
Transversality and lattice surgery: exploring realistic routes towards coupled logical qubits with trapped-ion quantum processors M. Gutiérrez, ..., A. Bermudez (2018)
arXiv:1801.07035 - 30 Citations

Active quantum error correction has been identified as a crucial ingredient of future quantum computers, motivating the recent experimental efforts to encode logical quantum bits using small topological codes. In addition to the demonstration of the beneficial role of the encoding, a break-even point in the progress towards large-scale quantum computers will be the implementation of a universal set of gates. This mid-term challenge will soon be faced by various quantum technologies, which urges the need of realistic assessments of their prospects. In this work, we pursue this goal by assessing the capability of current trapped-ion architectures in facing one of the most demanding parts of this quest: the implementation of an entangling CNOT gate between encoded logical qubits. We present a detailed comparative study of two alternative strategies for trapped-ion topological color codes, either a transversal or a lattice-surgery approach, characterized by a detailed microscopic modeling of both current technological capabilities and experimental sources of noise afflicting the different operations. Our careful fault-tolerant design, together with a low-resource optimization, allows us to determine via exhaustive numerical simulations the experimental regimes where each of the approaches becomes favorable. We hope that our study thereby contributes to guiding the future development of trapped-ion quantum computers.

The paper discusses trapped-ion quantum computers and touches on aspects related to ion transport and manipulation in quantum charge-coupled devices (QCCD), which involve ion shuttling and transport across junctions crucial for a 2D scalable design. However, the main focus of the paper is on implementing a universal set of gates for logical qubits coded in topological color codes and comparing approaches for trapped-ion topological color codes. The paper does not seem to explicitly address the experimental realizations of three-dimensional routing or shuttling. It does mention essential operations like ion shuttling but situates them within a 2D design context rather than a 3D one.

 🔴 [68]
A Quantum von Neumann Architecture for Large-Scale Quantum Computing Matthias F. Brandl (2017)
arXiv:1702.02583 - 15 Citations

As the size of quantum systems becomes bigger, more complicated hardware is required to control these systems. In order to reduce the complexity, I discuss the amount of parallelism required for a fault-tolerant quantum computer and what computation speed can be achieved in different architectures. To build a large-scale quantum computer, one can use architectural principles, from classical computer architecture, like multiplexing or pipelining. In this document, a Quantum von Neumann architecture is introduced which uses specialized hardware for the different tasks of a quantum computer, like computation or storage. Furthermore, it requires long qubit coherence and the capability to move quantum information between the different parts of the quantum computer. As an example, a Quantum von Neumann architecture for trapped ions is presented which incorporates multiplexing in the memory region for large-scale quantum computation. To illustrate the capability of this architecture, a model trapped ion quantum computer based on Quantum von Neumann architecture, the Quantum 4004, is introduced. Its hardware is optimized for simplicity and uses the classical Intel 4004 CPU from 1971 as a blueprint. The Quantum 4004 has only a single processing zone and is structured in 4 qubit packages. Its quantum memory can store up to 32768 qubit ions and its computation speed is 10 $\mu$s for single qubit operations and 20 $\mu$s for two-qubit operations.

The abstract of the paper primarily discusses the architectural principles in designing a large-scale quantum computer, using a Quantum von Neumann architecture. It suggests incorporating multiplexing in memory regions for trapped ions but does not indicate if ions are physically manipulated in three dimensions, nor does it focus on the experimental realizations of such a process. Moreover, the references cited touch on various aspects of trapped ion quantum computing but do not specifically discuss 3D routing or shuttling of ions, or the experimental methods involved in realizing such. Reference [92] mentions 'Near-ground-state transport of trapped-ion qubits through a multidimensional array,' which may imply some consideration of 3D pathways, but it appears to be more focused on near-ground-state transport rather than the specific 3D shuttling mechanisms of interest.

 🔴 [69]
Qubits on programmable geometries with a trapped-ion quantum processor Qiming Wu, ..., Jiehang Zhang (2023)
arXiv:2308.10179 - 2 Citations

Geometry and dimensionality have played crucial roles in our understanding of the fundamental laws of nature, with examples ranging from curved space-time in general relativity to modern theories of quantum gravity. In quantum many-body systems, the entanglement structure can change if the constituents are connected differently, leading to altered bounds for correlation growth and difficulties for classical computers to simulate large systems. While a universal quantum computer can perform digital simulations, an analog-digital hybrid quantum processor offers advantages such as parallelism. Here, we engineer a class of high-dimensional Ising interactions using a linear one-dimensional (1D) ion chain with up to 8 qubits through stroboscopic sequences of commuting Hamiltonians. %with a thorough understanding of the error sources and deviation from the target Hamiltonian. In addition, we extend this method to non-commuting circuits and demonstrate the quantum XY and Heisenberg models using Floquet periodic drives with tunable symmetries. The realization of higher dimensional spin models offers new opportunities ranging from studying topological phases of matter or quantum spin glasses to future fault-tolerant quantum computation.

The abstract and the introduction of the paper discuss engineering high-dimensional interactions and simulating higher dimensional spin models with up to 8 qubits in a linear one-dimensional ion chain. There is no mention of routing or shuttling ions in three dimensions or constructing and maneuvering ions along three-dimensional architectures explicitly. Instead, the work appears to center around quantum simulations using an already established ion chain. The experimental details described do not directly pertain to the physical 3D manipulation or routing of ions for quantum computing purposes as specified by the researcher.

 🔴 [70]
Quasienergy operators and generalized squeezed states for systems of trapped ions Bogdan M. Mihalcea (2021)
arXiv:2108.11628 - 4 Citations

Collective many-body dynamics for time-dependent quantum Hamiltonian functions is investigated for a dynamical system that exhibits multiple degrees of freedom, in this case a combined (Paul and Penning) trap. Quantum stability is characterized by a discrete quasienergy spectrum, while the quasienergy states are symplectic coherent states. We introduce the generators of the Lie algebra of the symplectic group ${\cal {SL}}(2, \mathbb R)$, which we use to build the coherent states (CS) associated to the system under investigation. The trapped ion is treated as a harmonic oscillator (HO) to which we associate the quantum Hamilton function. We obtain the kinetic and potential energy operators as functions of the Lie algebra generators and supply the expressions for the classical coordinate, momentum, kinetic and potential energy, as well as the total energy. In addition, we also infer the dispersions for the coordinate and momentum, together with the asymmetry and the flatness parameter for the distribution. The system interaction with laser radiation is also examined for a system of identical two-level atoms. The Hamilton function for the Dicke model is derived. The optical system is modelled as a HO (trapped ion) that undergoes interaction with an external laser field and we use it to engineer a squeezed state of the electromagnetic (EM) field. We consider coherent and squeezed states associated to both ion dynamics and to the EM field. Such an approach enables one to build CS in a compact and smart manner by use of the group theory.

The provided abstract and selected parts of the paper discuss the dynamics and control of trapped ions in the context of quantum computing but do not seem to explicitly address the specific process of routing or shuttling ions in three dimensions. Rather, the paper focuses on quantum stability, symplectic coherent states, Lie algebra generators, system interactions with laser radiation, and engineering of squeezed states related to two-level atomic systems. While trapped ion dynamics are a significant component of the paper, the context appears to be more theoretical and focused on Hamiltonian functions rather than hands-on, three-dimensional routing within a quantum computer.

 🔴 [71]
Microfabricated Ion Traps Marcus D. Hughes, ..., Winfried K. Hensinger (2011)
arXiv:1101.3207 - 72 Citations

Ion traps offer the opportunity to study fundamental quantum systems with high level of accuracy highly decoupled from the environment. Individual atomic ions can be controlled and manipulated with electric fields, cooled to the ground state of motion with laser cooling and coherently manipulated using optical and microwave radiation. Microfabricated ion traps hold the advantage of allowing for smaller trap dimensions and better scalability towards large ion trap arrays also making them a vital ingredient for next generation quantum technologies. Here we provide an introduction into the principles and operation of microfabricated ion traps. We show an overview of material and electrical considerations which are vital for the design of such trap structures. We provide guidance in how to choose the appropriate fabrication design, consider different methods for the fabrication of microfabricated ion traps and discuss previously realized structures. We also discuss the phenomenon of anomalous heating of ions within ion traps, which becomes an important factor in the miniaturization of ion traps.

While the paper clearly contributes valuable background information on microfabricated ion traps, which are important for trapped ion quantum computing, the focus seems to be on the principles, design, and challenges of microfabricated traps rather than on specific 3D routing or shuttling experiments. References to previous work suggest that considerations of motion are discussed, but the abstract and selected parts do not indicate detailed demonstrations of 3D ion routing/shuttling in an experimental quantum computing context. Therefore, the main topic of the paper doesn't center on experimental realizations of 3D shuttling but rather on the broader field of microfabricated ion traps and their implications in quantum computing.

 🔴 [72]
Rapid Exchange Cooling with Trapped Ions Spencer D. Fallek, ..., Kenton R. Brown (2023)
arXiv:2309.02581 - 0 Citations

The trapped-ion quantum charge-coupled device (QCCD) architecture is a leading candidate for advanced quantum information processing. In current QCCD implementations, imperfect ion transport and anomalous heating can excite ion motion during a calculation. To counteract this, intermediate cooling is necessary to maintain high-fidelity gate performance. Cooling the computational ions sympathetically with ions of another species, a commonly employed strategy, creates a significant runtime bottleneck. Here, we demonstrate a different approach we call exchange cooling. Unlike sympathetic cooling, exchange cooling does not require trapping two different atomic species. The protocol introduces a bank of $"$coolant$"$ ions which are repeatedly laser cooled. A computational ion can then be cooled by transporting a coolant ion into its proximity. We test this concept experimentally with two ions, executing the necessary transport in 107 $\mu s$, an order of magnitude faster than typical sympathetic cooling durations. We remove over 96%, and as many as 102(5) quanta, of axial motional energy from the computational ion. We verify that re-cooling the coolant ion does not decohere the computational ion. This approach validates the feasibility of a single-species QCCD processor, capable of fast quantum simulation and computation.

The abstract of this paper primarily discusses a new cooling method for trapped-ion quantum computing, known as 'exchange cooling,' rather than focusing on the 3D routing or shuttling of ions. While it does mention ion transport, the mechanism of transport appears related to facilitating cooling rather than exploring the technical aspects or achievements in 3D ion routing. The section of the paper provided further elaborates on quick ion transport and suggests that ions are rearranged between gate operations; however, it lacks explicit emphasis on three-dimensional control or experimental demonstrations of routing trapped ions in 3D in particular.

 🔴 [73]
Chip-integrated voltage sources for control of trapped ions J. Stuart, ..., J. Chiaverini (2018)
arXiv:1810.07152 - 34 Citations

Trapped-ion quantum information processors offer many advantages for achieving high-fidelity operations on a large number of qubits, but current experiments require bulky external equipment for classical and quantum control of many ions. We demonstrate the cryogenic operation of an ion-trap that incorporates monolithically-integrated high-voltage CMOS electronics ($\pm 8\mathrm{V}$ full swing) to generate surface-electrode control potentials without the need for external, analog voltage sources. A serial bus programs an array of 16 digital-to-analog converters (DACs) within a single chip that apply voltages to segmented electrodes on the chip to control ion motion. Additionally, we present the incorporation of an integrated circuit that uses an analog switch to reduce voltage noise on trap electrodes due to the integrated amplifiers by over $50\mathrm{dB}$. We verify the function of our integrated electronics by performing diagnostics with trapped ions and find noise and speed performance similar to those we observe using external control elements.

The abstract and provided excerpt of the paper focus on the integration of monolithically-integrated high-voltage CMOS electronics for generating control potentials in an ion-trap system. While this is critical for manipulating ions, the paper seems to concentrate on voltage source integration and noise reduction, rather than direct experimental evidence of 3D routing or shuttling of ions specifically within the context of a quantum computer. It suggests improvements for control systems that could enable complex architectures like arrays but does not explicitly mention 3D ion routing experiments or shuttling techniques.

 🔴 [74]
Operation of a planar-electrode ion-trap array with adjustable RF electrodes Muir Kumph, ..., Rainer Blatt (2014)
arXiv:1402.0791 - 28 Citations

One path to realizing systems of trapped atomic ions suitable for large-scale quantum computing and simulation is to create a two-dimensional array of ion traps. Interactions between nearest-neighbouring ions could then be turned on and off by tuning the ions' relative positions and frequencies. We demonstrate and characterize the operation of a planar-electrode ion-trap array. Driving the trap with a network of phase-locked radio-frequency (RF) resonators which provide independently variable voltage amplitudes we vary the position and motional frequency of a 40Ca+ ion in two dimensions within the trap array. With suitable miniaturization of the trap structure, this provides a viable architecture for large-scale quantum simulations.

The paper discusses the operation of a planar-electrode ion-trap array with the ability to alter the position of a calcium ion in two dimensions within the trap array. While the paper is certainly relevant to the general field of trapped ion quantum computing, and explores the manipulation of ions in an array that could potentially be part of a quantum computing architecture, it does not discuss or demonstrate the routing or shuttling of ions in three dimensions. Since the abstract and selected parts emphasize two-dimensional control, the topic is not fully aligned with the research interest in 3D ion routing within a quantum computer.

 🔴 [75]
Quantum Computation under Micromotion in a Planar Ion Crystal Sheng-Tao Wang, ..., Lu-Ming Duan (2014)
arXiv:1408.6659 - 27 Citations

We propose a scheme to realize scalable quantum computation in a planar ion crystal confined by a Paul trap. We show that the inevitable in-plane micromotion affects the gate design via three separate effects: renormalization of the equilibrium positions, coupling to the transverse motional modes, and amplitude modulation in the addressing beam. We demonstrate that all of these effects can be taken into account and high-fidelity gates are possible in the presence of micromotion. This proposal opens the prospect to realize large-scale fault-tolerant quantum computation within a single Paul trap.

This paper discusses a scheme for scalable quantum computation in a planar ion crystal confined by a Paul trap, largely focusing on challenges related to micromotion within a 2D framework. It aims to address issues in gate design caused by micromotion and proposes methods to achieve high-fidelity gates despite micromotion. However, the paper does not explicitly discuss the experimental realization of routing or shuttling ions in three dimensions. Instead, it seems to focus on overcoming the difficulties of micromotion for ions within a 2D plane while evaluating ion trap technologies and gate design. Thus, while the context of controlling ions within a Paul trap is relevant, the main topic of 3D routing or shuttling is not addressed by this paper.

 🔴 [76]
Many-Body Physics with Trapped Ions Christian Schneider, ..., Tobias Schaetz (2011)
arXiv:1106.2597 - 12 Citations

Direct experimental access to some of the most intriguing quantum phenomena is not granted due to the lack of precise control of the relevant parameters in their naturally intricate environment. Their simulation on conventional computers is impossible, since quantum behaviour arising with superposition states or entanglement is not efficiently translatable into the classical language. However, one could gain deeper insight into complex quantum dynamics by experimentally simulating the quantum behaviour of interest in another quantum system, where the relevant parameters and interactions can be controlled and robust effects detected sufficiently well. We report on the progress in experimentally simulating quantum many-body physics with trapped ions.

The provided sections of the paper focus on the broader concepts of simulating many-body physics with trapped ions and the progress in such quantum simulations. It discusses the potential scalability and various indirect techniques that could be useful in a quantum computing context, such as interactions with RF fields and optical supports. However, the specific practice of routing or shuttling trapped ions in three dimensions within a quantum computer is not directly addressed. Trapped ion movement along 3D pathways is a highly specialized topic that would likely involve detailed discussion of electrode design for 3D control, ion shuttling mechanics in such an environment, and specialized experiments targeted at showcasing these capabilities. The abstract and selected parts of the paper do not contain evidence of such specialized focus on 3D ion routing.

 🔴 [77]
Looped Pipelines Enabling Effective 3D Qubit Lattices in a Strictly 2D Device Zhenyu Cai, ..., Simon Benjamin (2022)
arXiv:2203.13123 - 5 Citations

Many quantum computing platforms are based on a two-dimensional physical layout. Here we explore a concept called looped pipelines which permits one to obtain many of the advantages of a 3D lattice while operating a strictly 2D device. The concept leverages qubit shuttling, a well-established feature in platforms like semiconductor spin qubits and trapped-ion qubits. The looped pipeline architecture has similar hardware requirements to other shuttling approaches, but can process a stack of qubit arrays instead of just one. Even a stack of limited height is enabling for diverse schemes ranging from NISQ-era error mitigation through to fault-tolerant codes. For the former, protocols involving multiple states can be implemented with a space-time resource cost comparable to preparing one noisy copy. For the latter, one can realise a far broader variety of code structures; as an example we consider layered 2D codes within which transversal CNOTs are available. Under reasonable assumptions this approach can reduce the space-time cost of magic state distillation by two orders of magnitude. Numerical modelling using experimentally-motivated noise models verifies that the architecture provides this benefit without significant reduction to the code's threshold.

The abstract and selected parts of the paper describe a 'looped pipeline' architecture that facilitates a kind of pseudo-3D lattice within what is essentially a 2D device infrastructure. This suggests that the approach allows for the exploitation of some of the benefits of 3D quantum computing, such as more complex error correction codes and enhanced computation techniques, through shuttling of qubits. However, the paper appears to emphasize a conceptual framework that bridges the gap between 2D and 3D architectures rather than providing concrete experimental results or techniques for actual 3D shuttling of trapped ions. It is more focused on the architecture allowing for complex coding and processing rather than the physical, experimental manipulation of trapped ions in 3D space.

 🔴 [78]
Materials Challenges for Trapped-Ion Quantum Computers Kenneth R. Brown, ..., Hartmut Häffner (2020)
arXiv:2009.00568 - 50 Citations

Trapped-ion quantum information processors store information in atomic ions maintained in position in free space via electric fields. Quantum logic is enacted via manipulation of the ions' internal and shared motional quantum states using optical and microwave signals. While trapped ions show great promise for quantum-enhanced computation, sensing, and communication, materials research is needed to design traps that allow for improved performance by means of integration of system components, including optics and electronics for ion-qubit control, while minimizing the near-ubiquitous electric-field noise produced by trap-electrode surfaces. In this review, we consider the materials requirements for such integrated systems, with a focus on problems that hinder current progress toward practical quantum computation. We give suggestions for how materials scientists and trapped-ion technologists can work together to develop materials-based integration and noise-mitigation strategies to enable the next generation of trapped-ion quantum computers.

The provided abstract and selected parts of the paper primarily focus on the materials challenges relevant to trapped-ion quantum computers, such as integrating system components and minimizing electric-field noise from trap electrodes. Although it discusses the basics of ion trapping and control of trapped-ion qubits, it does not specifically describe experiments or methods related to the 3D routing or shuttling of ions, which is the core interest of the research query.

 🔴 [79]
Native multiqubit Toffoli gates on ion trap quantum computers Nilesh Goel, ..., J. K. Freericks (2021)
arXiv:2103.00593 - 6 Citations

We examine the detailed scenario for implementing n-control-qubit Toffoli gates and select gates on ion-trap quantum computers, especially those that shuttle ions into interaction zones. We determine expected performance of these gates with realistic parameters for an ion-trap quantum computer and taking into account the time variation of the exchange integrals. This allows us to estimate the errors due to spin-phonon entanglement as well. While there are challenges with implementing these gates, because their performance always has some degree of error, they should be feasible on current hardware, but they may be too slow to be used efficiently in quantum codes on noisy intermediate scale quantum computers.

While the paper discusses ion trap quantum computers and mentions the concept of ion shuttling, its main focus is on the implementation and performance of multiqubit Toffoli gates in the context of ion-trap quantum computers. The abstract and provided text emphasize quantum gates, performance errors, and the movement of ions to interaction zones, but there is no specific mention of three-dimensional routing or shuttling. It suggests that ions move into interaction zones for entanglement, which primarily refers to the management of ions within a planar (perhaps 2D) architecture. The main concern of the paper appears to be the quantum gate operation rather than the 3D manipulation of the ions.

 🔴 [80]
Integrated $^{9}$Be$^{+}$ multi-qubit gate device for the ion-trap quantum computer Henning Hahn, ..., Christian Ospelkaus (2019)
arXiv:1902.07028 - 20 Citations

We demonstrate the experimental realization of a two-qubit M{\o}lmer-S{\o}rensen gate on a magnetic field-insensitive hyperfine transition in $^9$Be$^+$ ions using microwave-near fields emitted by a single microwave conductor embedded in a surface-electrode ion trap. The design of the conductor was optimized to produce a high oscillating magnetic field gradient at the ion position. The measured gate fidelity is determined to be $98.2\pm1.2\,\%$ and is limited by technical imperfections, as is confirmed by a comprehensive numerical error analysis. The conductor design can potentially simplify the implementation of multi-qubit gates and represents a self-contained, scalable module for entangling gates within the quantum CCD architecture for an ion-trap quantum computer.

The provided abstract and selected parts of the paper do not specifically address the physical routing or shuttling of ions through three-dimensional space within ion-trap quantum computers, which is central to the desired research topic. Instead, it focuses on the development of two-qubit entangling gates using microwave fields in a surface-electrode trap and addresses issues of fidelity and technical challenges associated with microwave-driven quantum operations. Although the mention of ion transport in the 'Quantum Charge-Coupled Device' (QCCD) architecture may suggest relevance, the paper does not seem to offer experimental details on 3D ion routing.

 🔴 [81]
Integrated Optical Approach to Trapped Ion Quantum Computation Jungsang Kim, ..., Changsoon Kim (2007)
arXiv:0711.3866 - 54 Citations

Recent experimental progress in quantum information processing with trapped ions have demonstrated most of the fundamental elements required to realize a scalable quantum computer. The next set of challenges lie in realization of a large number of qubits and the means to prepare, manipulate and measure them, leading to error-protected qubits and fault tolerant architectures. The integration of qubits necessarily require integrated optical approach as most of these operations involve interaction with photons. In this paper, we discuss integrated optics technologies and concrete optical designs needed for the physical realization of scalable quantum computer.

The paper in question seems to focus on the broader topic of quantum information processing, with emphasis on integrated optics and scalable ion trap chips for quantum information processors. It discusses elements like ion transport via electrostatic force, planar ion traps, and the integration necessary for quantum computing. However, the paper does not specifically address or delve into the nuances of routing or shuttling trapped ions in three dimensions. The mention of ion transport does signify relevance, but without explicit focus on the three-dimensional aspects, which are central to the specific topic of interest. Furthermore, since this paper is from 2007, it may precede the more advanced developments in 3D ion shuttling that the researcher is looking for.

 🔴 [82]
Ion trap with gold-plated alumina: substrate and surface characterization Myunghun Kim, ..., Moonjoo Lee (2022)
arXiv:2207.06878 - 1 Citations

We describe a complete development process of a segmented-blade linear ion trap. Alumina substrate is characterized with an X-ray diffraction and loss-tangent measurement. The blade is laser-micromachined and polished, followed by the sputtering and gold electroplating. Surface roughness is examined at each step of the fabrication via both electron and optical microscopies. On the gold-plated facet, we obtain a height deviation of tens of nanometers in the vicinity of the ion position. Trapping of laser-cooled $^{174}$Yb$^{+}$ ions is demonstrated.

The abstract and selected text from this paper focus on the development of a segmented-blade linear ion trap, including its design considerations and hardware fabrication, using techniques such as MEMS, CMOS, and microfabrications. Although the substrate's influence on the trap is thoroughly analyzed and the trapping of ions is demonstrated, it does not specifically describe the experimental realization of routing or shuttling ions in three dimensions. The primary concern of the paper is the construction and material characterization of the trap itself, rather than the dynamic control of ion movement in a three-dimensional space.

 🔴 [83]
Towards fault-tolerant quantum computing with trapped ions J. Benhelm, ..., R. Blatt (2008)
arXiv:0803.2798 - 419 Citations

Today ion traps are among the most promising physical systems for constructing a quantum device harnessing the computing power inherent in the laws of quantum physics. The standard circuit model of quantum computing requires a universal set of quantum logic gates for the implementation of arbitrary quantum operations. As in classical models of computation, quantum error correction techniques enable rectification of small imperfections in gate operations, thus allowing for perfect computation in the presence of noise. For fault-tolerant computation, it is commonly believed that error thresholds ranging between 10^-4 and 10^-2 will be required depending on the noise model and the computational overhead for realizing the quantum gates. Up to now, all experimental implementations have fallen short of these requirements. Here, we report on a Molmer-Sorensen type gate operation entangling ions with a fidelity of 99.3(1)% which together with single-qubit operations forms a universal set of quantum gates. The gate operation is performed on a pair of qubits encoded in two trapped calcium ions using a single amplitude-modulated laser beam interacting with both ions at the same time. A robust gate operation, mapping separable states onto maximally entangled states is achieved by adiabatically switching the laser-ion coupling on and off. We analyse the performance of a single gate and concatenations of up to 21 gate operations. The gate mechanism holds great promise not only for two-qubit but also for multi-qubit operations.

The provided abstract and selected parts of the paper focus on the implementation of high-fidelity quantum logic gates and quantum error correction, not specifically on the routing or shuttling of trapped ions in three dimensions. The text highlights the use of a Molmer-Sorensen type gate operation on trapped calcium ions and discusses the entanglement of ions with a fidelity of 99.3%, with no mention of three-dimensional ion manipulation. While the paper is relevant to quantum computing and trapped ion technology, it does not address the specifics of 3D shuttling of ions, which is the core interest in this literature review.

 🔴 [84]
A high-fidelity quantum matter-link between ion-trap microchip modules M. Akhtar, ..., W. K. Hensinger (2022)
arXiv:2203.14062 - 12 Citations

System scalability is fundamental for large-scale quantum computers (QCs) and is being pursued over a variety of hardware platforms. For QCs based on trapped ions, architectures such as the quantum charge-coupled device (QCCD) are used to scale the number of qubits on a single device. However, the number of ions that can be hosted on a single quantum computing module is limited by the size of the chip being used. Therefore, a modular approach is of critical importance and requires quantum connections between individual modules. Here, we present the demonstration of a quantum matter-