Article
Quantum Science & Technology
Chusei Kiumi, Kei Saito
Summary: Localization is a characteristic phenomenon in discrete-time space-inhomogeneous quantum walks, where particles remain localized around their initial position. This paper introduces an analytical method to calculate eigenvectors using a transfer matrix and extends the results to characterize eigenvalues for a more general space-inhomogeneous model. The time-averaged limit distributions of five models are derived to quantitatively evaluate localization and study the strong trapping property.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Physics, Multidisciplinary
Reinhold Blumel, Nikodem Grzesiak, Nhung H. Nguyen, Alaina M. Green, Ming Li, Andrii Maksymov, Norbert M. Linke, Yunseong Nam
Summary: To scale up quantum processors and achieve quantum advantage, a new gate-optimizing principle has been introduced to trade off negligible amounts of gate fidelity for substantial savings in power, leading to significant increases in gate speed and/or qubit connectivity. This method has been experimentally verified on a trapped-ion quantum computer and provides increased robustness to mode drift.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Eli Chertkov, Justin Bohnet, David Francois, John Gaebler, Dan Gresh, Aaron Hankin, Kenny Lee, David Hayes, Brian Neyenhuis, Russell Stutz, Andrew C. Potter, Michael Foss-Feig
Summary: An experiment with a trapped-ion quantum processor demonstrates the efficient simulation of the evolution of infinite entangled states using holographic technique and quantum tensor-network methods. The results show excellent quantitative agreement with theoretical predictions, indicating the potential of practical quantum computational advantage in science and technology.
Article
Multidisciplinary Sciences
Pavel Hrmo, Benjamin Wilhelm, Lukas Gerster, Martin W. van Mourik, Marcus Huber, Rainer Blatt, Philipp Schindler, Thomas Monz, Martin Ringbauer
Summary: Quantum information carriers naturally occupy high-dimensional Hilbert spaces, and high-dimensional (qudit) quantum systems are becoming a powerful resource for quantum processors. Generating the desired interaction efficiently in these systems is crucial. In this study, the authors demonstrate the implementation of a native two-qudit entangling gate up to dimension 5 in a trapped-ion system. They use a light-shift gate mechanism to generate genuine qudit entanglement in a single application of the gate, which seamlessly adapts to the local dimension of the system with a calibration overhead independent of the dimension. Native entangling techniques for qudits are important for encoding quantum information.
NATURE COMMUNICATIONS
(2023)
Article
Quantum Science & Technology
Nikodem Grzesiak, Andrii Maksymov, Pradeep Niroula, Yunseong Nam
Summary: This article discusses the importance of parallel operations in quantum computing and the advantages of EASE gates. By implementing EASE gates in parallel, efficient quantum circuits can be realized on trapped-ion quantum computers, which is significant for quantum chemistry simulations and pattern matching algorithms.
Article
Physics, Multidisciplinary
Kenta Higuchi
Summary: This article explores the relationship between the discrete quantum walk on Z and the continuous Schrodinger operator on R in the scattering problem, highlighting the countable sum of probability amplitudes associated with the paths of the quantum walker and the scattering matrix entries. The barrier-top scattering corresponds to the Hadamard walk in the semiclassical limit.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Multidisciplinary Sciences
J. M. Pino, J. M. Dreiling, C. Figgatt, J. P. Gaebler, S. A. Moses, M. S. Allman, C. H. Baldwin, M. Foss-Feig, D. Hayes, K. Mayer, C. Ryan-Anderson, B. Neyenhuis
Summary: The QCCD proposal outlines a blueprint for a universal quantum computer using mobile ions as qubits, limiting quantum interactions to small ion crystals to maintain low error rates demonstrated in small experiments. The integration of necessary elements into a programmable trapped-ion quantum computer has led to the realization of a teleported CNOT gate with negligible crosstalk error and high quantum volume, showing the potential for high-performance quantum computers.
Article
Computer Science, Information Systems
Jonathan H. A. de Carvalho, Luciano S. de Souza, Fernando M. de Paula Neto, Tiago A. E. Ferreira
Summary: This paper investigates the application of the lackadaisical quantum walk to search for multiple solutions on grids, addressing issues such as suitable stopping conditions, the impact of solution density and relative distance on success probability, and the generalization to search in arbitrary dimensions. The study also proposes an optimal adjustment of the self-loop weight and discovers a connection between the lackadaisical quantum walk and Grover's algorithm.
INFORMATION SCIENCES
(2023)
Article
Physics, Multidisciplinary
Yukio Kawashima, Erika Lloyd, Marc P. Coons, Yunseong Nam, Shunji Matsuura, Alejandro J. Garza, Sonika Johri, Lee Huntington, Valentin Senicourt, Andrii O. Maksymov, Jason H. V. Nguyen, Jungsang Kim, Nima Alidoust, Arman Zaribafiyan, Takeshi Yamazaki
Summary: Problem decomposition methods can help overcome size limitations of quantum hardware for large-scale electronic structure simulations. Researchers demonstrated experimentally that decomposing a large molecule into smaller fragments can be applicable to currently available quantum computers, showcasing the potential of quantum hardware in material design and drug discovery.
COMMUNICATIONS PHYSICS
(2021)
Article
Optics
Prajit Dhara, Norbert M. Linke, Edo Waks, Saikat Guha, Kaushik P. Seshadreesan
Summary: Trapped ions have the potential to serve as quantum repeaters in long distance quantum communication due to their advanced technology platform. The use of hybrid traps with two distinct species of ions can enhance the entanglement distribution rate, making trapped-ion systems more feasible and important in this field.
Article
Quantum Science & Technology
Yoshihiro Anahara, Norio Konno, Hisashi Morioka, Etsuo Segawa
Summary: This paper examines the stationary state of a quantum walk on a finite path, focusing on the comfortability of the quantum walker at different vertices. By analyzing the limit distribution of the comfortability as the path length approaches infinity, a weak convergence theorem is derived.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Quantum Science & Technology
Mingyu Kang, Qiyao Liang, Ming Li, Yunseong Nam
Summary: To achieve high-fidelity operations on a large-scale quantum computer, the parameters of the physical system must be efficiently characterized with high accuracy. For trapped ions, the entanglement between qubits is mediated by the motional modes of the ion chain, and thus characterizing the motional-mode parameters becomes essential. In this paper, physical models are developed to accurately predict both magnitude and sign of the Lamb-Dicke parameters when the modes are probed in parallel. An advanced characterization protocol is also devised to significantly shorten the characterization time compared to the conventional method.
QUANTUM SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Applied
D. T. C. Allcock, W. C. Campbell, J. Chiaverini, I. L. Chuang, E. R. Hudson, I. D. Moore, A. Ransford, C. Roman, J. M. Sage, D. J. Wineland
Summary: This article outlines an alternative approach for flexible encoding capabilities in single-species trapped ion systems using long-lived metastable states as a programmable second species. The additional trapped ion primitives needed for this protocol are compatible with large-scale systems already in operation.
APPLIED PHYSICS LETTERS
(2021)
Article
Quantum Science & Technology
Shuji Kuriki, Md Sams Afif Nirjhor, Hiromichi Ohno
Summary: This study explores the unitary equivalence classes of quantum walks on cycles, finding that they are determined by 2N parameters and that the ranges of two of these parameters are restricted depending on the parity of N.
QUANTUM INFORMATION PROCESSING
(2021)
Article
Quantum Science & Technology
Yingyue Zhu, Zewen Zhang, Bhuvanesh Sundar, Alaina M. Green, C. Huerta Alderete, Nhung H. Nguyen, Kaden R. A. Hazzard, Norbert M. Linke
Summary: This paper investigates the feasibility of applying the quantum approximate optimization algorithm (QAOA) to combinatorial optimization problems on graphs. The results show that QAOA's performance improves with the number of rounds and an advanced mixing Hamiltonian allows sampling of all optimal solutions.
QUANTUM SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Multidisciplinary
Wan-Jun Su, Guang-Zheng Ye, Ya-Dong Wu, Zhen-Biao Yang, Barry C. Sanders
Summary: In this study, we propose a scheme to achieve nuclear-nuclear indirect interactions mediated by a mechanically driven nitrogen-vacancy (NV) center in a diamond. We demonstrate experimental results of two-qubit entangling gates and quantum-state transfer, and find that the scheme is robust against decoherence caused by coupling between the NV center (nuclear spins) and the environment, and insensitive to fluctuating positions of the nuclear spins and the NV center. This scheme provides a general blueprint for multi-nuclear-spin gates and multi-party communication.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Chao Chen, Xing Ding, Jian Qin, Jizhou Wu, Yu He, Chao-Yang Lu, Li Li, Xiong-Jun Liu, Barry C. Sanders, Jian-Wei Pan
Summary: The dissipationless chiral edge states in spin-orbit coupled anomalous Floquet topological phase exhibit nontrivial topological spin texture on boundaries, which can inspire novel topology-based spintronic phenomena and devices.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Peng Xue, Xingze Qiu, Kunkun Wang, Barry C. Sanders, Wei Yi
Summary: Topological edge states in non-Hermitian parity-time (PT)-symmetric systems were experimentally detected in photonic quantum walks with spontaneously broken PT symmetry, providing a complete description of topological phenomena. The global Berry phase in PT-symmetric quantum-walk dynamics unambiguously defines topological invariants of the system in both the PT-symmetry-unbroken and broken regimes. These results establish a unified framework and a useful method to observe topological phenomena in PT-symmetric non-Hermitian systems.
NATIONAL SCIENCE REVIEW
(2023)
Article
Physics, Multidisciplinary
Abdul Wahab, Muqaddar Abbas, Barry C. Sanders
Summary: In this study, an atomic grating is proposed based on the phenomenon of electromagnetically induced transparency. The grating is able to switch between zeroth-order diffraction and a distinct higher-order diffraction pattern by driving a planar gaseous medium of a four-level tripod atoms with three laser beams. The behavior of the diffraction intensities of different orders is numerically investigated by varying the field detunings and orbital angular momentum number of the composite vortex light beam. The proposed scheme may have potential applications in optical memory devices by storing information to diffraction orders of the atomic grating.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
Yi-Zheng Zhen, Yingqiu Mao, Yu-Zhe Zhang, Feihu Xu, Barry C. Sanders
Summary: Device-independent quantum key distribution (DIQKD) is a secure method against adversaries with scalable quantum computers and malicious key establishment systems, but the current key rate is low. Therefore, we propose a DIQKD scheme based on the quantum nonlocal Mermin-Peres magic square game, which asymptotically delivers DIQKD against collective attacks even with noise. Our scheme outperforms DIQKD using the Clauser-Horne-Shimony-Holt game in terms of the number of game rounds, provided that both state visibility and detection efficiency are high enough.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Yingkai Ouyang, Kaumudibikash Goswami, Jacquiline Romero, Barry C. Sanders, Min-Hsiu Hsieh, Marco Tomamichel
Summary: In this paper, we introduce and analyze the concept of approximate quantum secret sharing in a formal cryptographic setting. The goal is to allow authorized players to approximately reconstruct a quantum secret, while denying access to nonauthorized players. We show that this is possible if the information leakage, measured in terms of entanglement-assisted capacity of the complementary quantum channel, is small for players outside the authorized structure and the environment.
Article
Physics, Multidisciplinary
Seyed Shakib Vedaie, Eduardo J. Paez, Nhung H. Nguyen, Norbert M. Linke, Barry C. Sanders
Summary: Researchers have successfully implemented a two-qubit gate in an ion chain using addressed Raman beams. They have optimized quantum control techniques to achieve reductions in gate duration and gate error rate.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Optics
Xiao-Xu Fang, Kui An, Bai-Tao Zhang, Barry C. Sanders, He Lu
Summary: We study maximal coin-position entanglement generation via a discrete-time quantum walk, in which the coin operation is randomly selected from one of two coin operators set at each step. We solve maximal entanglement generation as an optimization problem with quantum process fidelity as the cost function. Then we determine the maximal entanglement that can be rigorously generated for any step beyond the second regardless of initial conditions with appropriate coin sequences. The simplest coin sequence comprising Hadamard and identity operations is equivalent to the generalized elephant quantum walk, which exhibits an increasingly faster spreading in terms of probability distribution. Experimentally, we demonstrate a ten-step quantum walk driven by such coin sequences with linear optics and thereby show the desired high-dimensional bipartite entanglement as well as the transport behavior of faster spreading.
Article
Physics, Fluids & Plasmas
Carlo Maria Scandolo, Gilad Gour, Barry C. Sanders
Summary: We develop a rigorous theory of external influences on finite discrete dynamical systems, going beyond the perturbation paradigm. The theory of covariant influences is developed using resource theories, for both deterministic and stochastic evolutions. We provide necessary and sufficient conditions for state transitions under deterministic covariant influences and necessary conditions in the presence of stochastic covariant influences, predicting forbidden transitions between states. Our approach, employing the framework of resource theories, unifies the behavior of different types of finite discrete dynamical systems.
Article
Physics, Multidisciplinary
Jizhou Wu, Barry C. Sanders
Summary: This study presents a scheme to enable the observation of higher-order multiphoton collective phases by designing a sparse interferometer, which greatly reduces complexity compared to existing schemes. The scheme addresses a major obstacle in observing large-scale collective phases by reducing optical depth and the number of beam splitters.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Kunal Sharma, Barry C. Sanders, Mark M. Wilde
Summary: This paper proposes an optimal test for measuring the performance of continuous-variable quantum teleportation and provides an analytical solution for the energy-constrained diamond distance between a photodetector and its experimental approximation. The results are relevant for experiments using continuous-variable teleportation and photodetectors.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Shu Xu, Joerg Schmiedmayer, Barry C. Sanders
Summary: This study proposes a method for Bose-Einstein condensate (BEC) interferometry and quantum logic based on nonlinear quantum mechanics. By solving the equation for evolution, a rigorous foundation for quantum gates is established, and feasible nonlinear interferometry devices are designed by combining quantum-control techniques and appropriate state-sampling techniques.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Optics
Pengcheng Liao, Barry C. Sanders, David L. Feder
Summary: Determining whether a given family of quantum states is topologically ordered is a significant problem in condensed matter physics and quantum information theory. Researchers have derived necessary and sufficient conditions for graph states to be in a specific class of quantum error-correction code states. They have applied these conditions to various graph families, including star and complete graphs, and discussed which ones are topologically ordered and how to construct the codewords. The researchers have also used this formalism to construct several codes with macroscopic distance, including a three-dimensional topological code with a large number of encoded logical qubits.
Article
Physics, Multidisciplinary
Dylan Spivak, Murphy Yuezhen Niu, Barry C. Sanders, Hubert de Guise
Summary: Using representation theory, this paper derives expressions for the coincidence rate of partially-distinguishable particles in interferometry experiments, valid for any number of bosons or fermions. The research aids in understanding systems with arbitrary levels of distinguishability and introduces a sampling scheme for partially-distinguishable fermions.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Salini Karuvade, Abhijeet Alase, Barry C. Sanders
Summary: In quantum mechanics, physical states are represented by rays in Hilbert space H, which is a vector space with an inner product. The inner product represents the overlap between |psi>, a description of a pure state (preparation), and |psi>.
PHYSICAL REVIEW RESEARCH
(2022)
