Article
Management
Giacomo Nannicini
Summary: This paper proposes quantum subroutines for the simplex method, which eliminate the classical computation of the basis inverse. The author shows how to quantize all steps of the simplex algorithm, achieving polynomial speedup in problem dimension but with worse dependence on other numerical parameters. The quantum subroutines have advantages in scalability for well-conditioned sparse problems.
OPERATIONS RESEARCH
(2022)
Article
Quantum Science & Technology
Akram Youssry, Hendra Nurdin
Summary: In this paper, the problem of open-loop control of a qubit coupled to an unknown fully quantum non-Markovian noise is investigated. A graybox model obtained from measurement data is utilized to approximate the unknown quantum noise. The estimated model is then used for calculating the open-loop control pulses under constraints on amplitude and timing. Gradient descent and genetic optimization methods are explored for pulse optimization. The impact of finite sampling on estimating expectation values of observables is considered, and results for single- and multi-axis control of a qubit are presented.
QUANTUM SCIENCE AND TECHNOLOGY
(2023)
Article
Computer Science, Information Systems
Giovanni Acampora, Autilia Vitiello
Summary: This study introduces a new evolutionary algorithm utilizing an actual quantum processor, which employs quantum phenomena to achieve significant speed-up in computation. By implementing quantum concepts such as quantum chromosome and entangled crossover, the proposed algorithm efficiently executes genetic evolution on quantum devices to converge towards proper sub-optimal solutions of a given optimization problem. The experimental results show that the synergy between quantum and evolutionary computation leads to a promising bio-inspired optimization strategy.
INFORMATION SCIENCES
(2021)
Article
Automation & Control Systems
Juan C. Travieso-Torres, Camilo Contreras, Francisco Hernandez, Manuel A. Duarte-Mermoud, Norelys Aguila-Camacho, Marcos E. Orchard
Summary: This research proposes a normalized APBC (NAPBC) for nonlinear dynamical systems with an unknown direction of control, extending the design of adaptive passivity-based controllers (APBC). The proposed method can handle unknown control direction using a simpler alternative method and has fewer parameters than Nussbaum gains. The stability proof of the controlled system is presented, and the NAPBC expands the tuning method for normalized fixed gains or time-varying gains, reducing the trial and error procedure.
Article
Multidisciplinary Sciences
Kang-Da Wu, Chengran Yang, Ren-Dong He, Mile Gu, Guo-Yong Xiang, Chuan-Feng Li, Guang-Can Guo, Thomas J. Elliott
Summary: Complex systems can be understood and predicted using stochastic modelling, which is widely used in quantitative sciences. Quantum technologies can reduce the memory dimension needed for accurate modelling of non-Markovian processes, providing higher precision than classical models. In this study, the authors demonstrate analytically and experimentally that a single qubit memory can be used for memory-efficient quantum modelling of non-Markovian processes, filling a gap in previous research.
NATURE COMMUNICATIONS
(2023)
Article
Quantum Science & Technology
Xiaodie Lin, Zhenyu Chen, Zhaohui Wei
Summary: In this paper, neural networks are trained to quantify unknown quantum entanglement using outcome statistics data from measuring target quantum states with local or single-qubit Pauli observables as input features and well-chosen quantities as training labels. The trained neural networks show excellent performance in quantifying unknown quantum entanglement, surpassing previous approaches in both precision and application range. It is also observed that neural networks tend to perform better on quantum states with stronger quantum nonlocality, even without any prior knowledge about quantum nonlocality.
QUANTUM INFORMATION PROCESSING
(2023)
Article
Physics, Multidisciplinary
Yuxiang Yang, Renato Renner, Giulio Chiribella
Summary: This article investigates how much energy is required to implement a desired unitary gate on a quantum system with a non-trivial energy spectrum and derives a general lower bound on the energy requirement. The extension of the main results to systems with unbounded Hamiltonians has immediate applications in quantum information processing with optical systems and provides bounds on the energy requirement of continuous variable quantum gates.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Computer Science, Artificial Intelligence
Fei Yan, Salvador E. Venegas-Andraca, Kaoru Hirota
Summary: Quantum image processing is an interdisciplinary field that aims to surpass the limits of traditional computing by utilizing quantum effects. Key issues in this field include improving quantum image representations, designing quantum algorithms, and developing physical equipment and software architecture.
Article
Computer Science, Artificial Intelligence
YaoChong Li, Ri-Gui Zhou, RuiQing Xu, Jia Luo, WenWen Hu, Ping Fan
Summary: This article investigates three graph-theoretic feature selection methods, formulates the problems as quadratic problems in binary variables, and solves them using the quantum approximate optimization algorithm (QAOA). It proposes a method for solving large-scale problems and validates the effectiveness through numerical experiments.
IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS
(2022)
Article
Chemistry, Multidisciplinary
Seung-Hun Han, Manh Son Tran, Duc-Thien Tran
Summary: This paper presents an adaptive sliding mode control method with a Nussbaum function to address the tracking control issue for manipulators and handle unknown friction and control direction. The proposed method guarantees tracking accuracy and fast responses, with adaptive laws for robust gain and reduction of chattering effect. Simulation results on a 3-DOF manipulator demonstrate the advantages of the proposed method.
APPLIED SCIENCES-BASEL
(2021)
Article
Automation & Control Systems
Jing Wu, Wei Sun, Shun-Feng Su, Yuqiang Wu
Summary: This study introduces an adaptive quantized control scheme for uncertain strict-feedback nonlinear systems with unknown control directions. By combining backstepping technique and Lyapunov stability theory, a systematic analysis method is designed to overcome obstacles related to quantized input signals and unknown control directions. The effectiveness and feasibility of the control scheme are verified through simulation examples, demonstrating the boundedness of all signals and convergence of tracking error to a small domain of origin.
INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL
(2021)
Article
Physics, Multidisciplinary
Hatim Salih, Jonte R. Hance, Will McCutcheon, Terry Rudolph, John Rarity
Summary: This study introduces a method of directly manipulating any qubit without exchanging particles, and applies it to the exchange-free preparation of quantum states and computations remotely. Additionally, it demonstrates the exchange-free control of a universal two-qubit gate, enabling the remote execution of desired algorithms on a programmable quantum circuit.
NEW JOURNAL OF PHYSICS
(2021)
Article
Computer Science, Artificial Intelligence
Bingyun Liang, Shiqi Zheng, Choon Ki Ahn, Feng Liu
Summary: This article focuses on the study of a decentralized fuzzy control method for a class of fractional-order interconnected systems with unknown control directions. A novel fractional-order Nussbaum function technique is proposed to handle the multiple unknown control directions and is applicable for both fractional and integer-order systems. Fuzzy logic systems are also used to approximate unknown nonlinearities.
IEEE TRANSACTIONS ON FUZZY SYSTEMS
(2022)
Article
Quantum Science & Technology
Guang Hao Low, Yuan Su, Yu Tong, Minh C. Tran
Summary: We develop methods to perform faster Trotter steps with sub-linear gate complexity and lower rank Hamiltonian coefficients. We also show an improved gate count for simulating uniform electron gas and external potential of nuclei. We prove a lower bound for evolving generic n-qubit two-local Hamiltonians with accuracy, suggesting the use of Hamiltonian structural properties for lower gate complexity in Trotter steps.
Article
Computer Science, Artificial Intelligence
Shiqi Zheng, Peng Shi, Shuoyu Wang, Yan Shi
Summary: This article explores the decentralized stabilization problem of stochastic interconnected systems, proposing state and output feedback controllers for these systems with the use of barrier Lyapunov-Krasivskii functions for stability analysis. Fuzzy systems are adopted to approximate complex and unknown dynamics, proving that all states will stay within a compact set using barrier functions and switching mechanism. An adaptive compensator is presented to handle errors from input quantization, achieving asymptotic stability of the interconnected systems.
IEEE TRANSACTIONS ON FUZZY SYSTEMS
(2021)
Article
Multidisciplinary Sciences
Alexander Erhard, Hendrik Poulsen Nautrup, Michael Meth, Lukas Postler, Roman Stricker, Martin Stadler, Vlad Negnevitsky, Martin Ringbauer, Philipp Schindler, Hans J. Briegel, Rainer Blatt, Nicolai Friis, Thomas Monz
Summary: This study reports the experimental realization of lattice surgery between two qubits protected via a topological error-correction code in a ten-qubit ion-trap quantum information processor. Through a series of local and entangling gates, as well as measurements on auxiliary qubits, necessary quantum non-demolition measurements can be carried out, demonstrating entanglement between two logical qubits and logical state teleportation between them.
Article
Quantum Science & Technology
Simon Morelli, Ayaka Usui, Elizabeth Agudelo, Nicolai Friis
Summary: Bayesian analysis provides a framework for parameter estimation that is advantageous in uncertain situations where frequentist analysis may not be well defined. The study examines three paradigmatic estimation schemes in continuous-variable quantum metrology and identifies Bayesian estimation strategies that offer good performance and potential for experimental realization. This research bridges the gap between achievable uncertainties with local estimation techniques and asymptotically optimal strategies.
QUANTUM SCIENCE AND TECHNOLOGY
(2021)
Article
Multidisciplinary Sciences
V. Saggio, B. E. Asenbeck, A. Hamann, T. Stroemberg, P. Schiansky, V. Dunjko, N. Friis, N. C. Harris, M. Hochberg, D. Englund, S. Woelk, H. J. Briegel, P. Walther
Summary: As artificial intelligence advances, reinforcement learning becomes increasingly important. Although some studies have used quantum mechanics to speed up the decision-making process of agents, a reduction in learning time has not yet been demonstrated.
Article
Quantum Science & Technology
J. Miguel-Ramiro, A. Pirker, W. Dur
Summary: By providing the possibility of handling superposed tasks and superposed addressing, we make quantum networks genuine quantum. This functionality extension relies on a quantum control register, offering great potential and advantages, but requires specific conditions for implementation.
NPJ QUANTUM INFORMATION
(2021)
Article
Quantum Science & Technology
Arne Hamann, Pavel Sekatski, Wolfgang Duer
Summary: This paper investigates the sensing of scalar valued fields with specific spatial dependence using a network of sensors. By constructing a decoherence-free subspace, the specific signal can be accurately sensed while being insensitive to other signals at different positions or with unequal spatial dependence. The concept of an approximate decoherence-free subspace is introduced to suppress noise while controlling the signal strength. An efficient formalism is introduced to construct internal states and sensor configurations, and several examples are analyzed and applied to demonstrate the usefulness and wide applicability of the approach.
QUANTUM SCIENCE AND TECHNOLOGY
(2022)
Article
Physics, Multidisciplinary
Jorge Miguel-Ramiro, Ferran Riera-Sabat, Wolfgang Duer
Summary: This study introduces collective strategies for the efficient, local verification of ensembles of Bell pairs, reducing the number of entangled pairs that need to be measured and destroyed by utilizing initial information and noise transfer. The remaining states can be directly certified.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Ferran Riera-Sabat, Pavel Sekatski, Wolfgang Duer
Summary: In a quantum simulator based on logical systems, physical qubits are used to represent logical systems and achieve enhanced control over effective interactions. By manipulating the internal state of the logical systems, one can directly control the topology and strength of the effective interactions. This leads to a universal quantum simulator with advantages over standard ones.
NEW JOURNAL OF PHYSICS
(2023)
Article
Quantum Science & Technology
J. Miguel-Ramiro, A. Pirker, W. Duer
Article
Quantum Science & Technology
Philip Taranto, Faraj Bakhshinezhad, Andreas Bluhm, Ralph Silva, Nicolai Friis, Maximilian P. E. Lock, Giuseppe Vitagliano, Felix C. Binder, Tiago Debarba, Emanuel Schwarzhans, Fabien Clivaz, Marcus Huber
Summary: Thermodynamics links our understanding of the world to our ability to manipulate and control it. The third law of thermodynamics and Nernst's unattainability principle highlight the need for infinite resources to cool a system to absolute zero temperature. This study provides a framework for identifying the resources required for creating pure quantum states, and extends Landauer's principle to a thermodynamic setting. It emphasizes the importance of control and demonstrates the connection between information and thermodynamics.
Article
Optics
Maria Flors Mor-Ruiz, Wolfgang Duer
Summary: Despite the complexity of describing multiqubit quantum states and processes, efficient methods for certain families of states and operations have been developed. The stabilizer formalism and the Gottesman-Knill theorem are prominent examples, where pure stabilizer or graph states are manipulated using specific operations. In this study, a method called noisy stabilizer formalism is developed, which allows efficient description of quantum states under noisy conditions. This method is particularly useful for multipartite entangled states generated by local Pauli measurements on noisy stabilizer states.
Article
Optics
Ferran Riera-Sabat, Jorge Miguel-Ramiro, Wolfgang Duer
Summary: This study proposes several methods to directly distinguish between two different sets of states, for example, whether their fidelity is above or below a certain threshold value. These methods are more efficient and can keep the verified states intact. The study makes use of auxiliary entanglement or an ensemble of larger size, operating on the whole ensemble but measuring only a small fraction where information has been concentrated. For certain state families, this approach can even outperform optimal methods that collectively measure a fixed fraction of the ensemble.
Article
Quantum Science & Technology
Ferran Riera-Sabat, Pavel Sekatski, Wolfgang Duer
Summary: By adding a controlled auxiliary system that couples with the system qubits via a always-on, distant-dependent interaction, we demonstrate a way to mediate entanglement between different subsystems in a controlled manner without any quantum control. Simply by changing the internal state of the control system, it can selectively couple to selected qubits and generate various types of entanglement within the system. This provides an alternative approach for quantum control and quantum gates that does not rely on the ability to switch interactions on and off at will, and serves as a locally controlled quantum switch capable of creating all entanglement patterns. We also show that this approach offers increased error tolerance with respect to position fluctuations.
Article
Quantum Science & Technology
Jorge Miguel-Ramiro, Ferran Riera-Sabat, Wolfgang Duer
Summary: This paper introduces a quantum repeater protocol to distribute three-qubit W states over arbitrary distances in a two-dimensional triangular quantum network. The repeater protocol enables efficient applications between remote parties by combining probabilistic entanglement swapping and an improved entanglement purification protocol. The protocol also allows for error handling and provides analysis of error thresholds, achievable fidelities, and overheads.
Article
Quantum Science & Technology
Simon Morelli, David Sauerwein, Michalis Skotiniotis, Nicolai Friis
Summary: In this paper, we study the distribution of high-dimensional entangled states through noisy channels and the conversion of these states to desired target states through stochastic local operations and classical communication. We propose a channel-estimation strategy that uses unsuccessful conversion copies to estimate the noise and counteract its effect. We focus on the scenario where only finitely many copies are distributed and parties do not process multiple copies simultaneously. We compare our strategy with more general but less practically implementable strategies involving distillation and quantum memories.
Article
Quantum Science & Technology
Hayata Yamasaki, Simon Morelli, Markus Miethlinger, Jessica Bavaresco, Nicolai Friis, Marcus Huber
Summary: The article explores the challenges of characterizing different types of entanglement in entanglement shared among multiple parties. It introduces the concept of genuine multipartite entanglement to distinguish states that cannot be produced by mixing partition-separable states. The study shows that multiple copies of the same state can unlock genuine multipartite entanglement, even from partially separable states and undistillable ensembles.
