PRA: Quantum information

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Recently published articles in Phys. Rev. A in the Table of Content section "Quantum information"
Updated: 51 min 46 sec ago

Experimental investigation of equivalent Laplacian and adjacency quantum walks on irregular graphs

Mon, 2022-06-27 12:00

Author(s): Dengke Qu, Lei Xiao, Kunkun Wang, Xiang Zhan, and Peng Xue

The continuous-time quantum walk denotes the evolution of a particle on a given graph governed by Schrödinger's equation. For different applications, the corresponding Hamiltonian is proportional to either the Laplacian or the adjacency matrix of the graph. The two quantum walks are equivalent on re…


[Phys. Rev. A 105, 062448] Published Mon Jun 27, 2022

Categories: Journals, Physics

Analysis of quantum correlations within the ground state of a three-level Lipkin model

Mon, 2022-06-27 12:00

Author(s): Javier Faba, Vicente Martín, and Luis Robledo

The performance of beyond mean-field methods in solving the quantum many-body problem for fermions is usually characterized by the correlation energy measured with respect to the underlying mean-field value. In this paper we address the issue of characterizing the amount of correlations associated t…


[Phys. Rev. A 105, 062449] Published Mon Jun 27, 2022

Categories: Journals, Physics

Entanglement resonance in the asymmetric quantum Rabi model

Mon, 2022-06-27 12:00

Author(s): Yu-Qing Shi, Lei Cong, and Hans-Peter Eckle

We investigate the entanglement features in the interacting system of a quantized optical field and a two-level system which is statically driven, known as the asymmetric quantum Rabi model (AsymQRM). Intriguing entanglement resonance valleys with the increase of the photon-atom coupling strength an…


[Phys. Rev. A 105, 062450] Published Mon Jun 27, 2022

Categories: Journals, Physics

Progress toward larger molecular simulation on a quantum computer: Simulating a system with up to 28 qubits accelerated by point-group symmetry

Mon, 2022-06-27 12:00

Author(s): Changsu Cao, Jiaqi Hu, Wengang Zhang, Xusheng Xu, Dechin Chen, Fan Yu, Jun Li, Han-Shi Hu, Dingshun Lv, and Man-Hong Yung

The exact evaluation of the molecular ground state in quantum chemistry requires an exponentially increasing computational cost. Quantum computation is a promising way to overcome the exponential problem using polynomial-time quantum algorithms. A quantum-classical hybrid optimization scheme known a…


[Phys. Rev. A 105, 062452] Published Mon Jun 27, 2022

Categories: Journals, Physics

Incompatibility measures in multiparameter quantum estimation under hierarchical quantum measurements

Fri, 2022-06-24 12:00

Author(s): Hongzhen Chen, Yu Chen, and Haidong Yuan

The incompatibility of the measurements constrains the achievable precisions in multiparameter quantum estimation. Understanding the tradeoff induced by such incompatibility is a central topic in quantum metrology. Here we provide an approach to study the incompatibility under general p-local measur…


[Phys. Rev. A 105, 062442] Published Fri Jun 24, 2022

Categories: Journals, Physics

Robust optimization for quantum reinforcement learning control using partial observations

Fri, 2022-06-24 12:00

Author(s): Chen Jiang, Yu Pan, Zheng-Guang Wu, Qing Gao, and Daoyi Dong

The current quantum reinforcement learning control models often assume that the quantum states are known a priori for control optimization. However, full observation of the quantum state is experimentally infeasible due to the exponential scaling of the number of required quantum measurements on the…


[Phys. Rev. A 105, 062443] Published Fri Jun 24, 2022

Categories: Journals, Physics

Quantum signal processing for simulating cold plasma waves

Fri, 2022-06-24 12:00

Author(s): I. Novikau, E. A. Startsev, and I. Y. Dodin

Numerical modeling of radio-frequency waves in plasma with sufficiently high spatial and temporal resolution remains challenging even with modern computers. However, such simulations can be sped up using quantum computers in the future. Here, we propose how to do such modeling for cold plasma waves,…


[Phys. Rev. A 105, 062444] Published Fri Jun 24, 2022

Categories: Journals, Physics

Quantum state transfer between a frequency-encoded photonic qubit and a quantum-dot spin in a nanophotonic waveguide

Fri, 2022-06-24 12:00

Author(s): Ming Lai Chan, Ziv Aqua, Alexey Tiranov, Barak Dayan, Peter Lodahl, and Anders S. Sørensen

We propose a deterministic yet fully passive scheme to transfer the quantum state from a frequency-encoded photon to the spin of a quantum dot mediated by a nanophotonic waveguide. We assess the quality of the state transfer by studying the effects of all relevant experimental imperfections on the s…


[Phys. Rev. A 105, 062445] Published Fri Jun 24, 2022

Categories: Journals, Physics

Preparing many copies of a quantum state in the black-box model

Thu, 2022-06-23 12:00

Author(s): Yassine Hamoudi

We describe a simple quantum algorithm for preparing K copies of an N-dimensional quantum state whose amplitudes are given by a quantum oracle. Our result extends a previous work of Grover, who showed how to prepare one copy in time O(N). In comparison with the naive O(KN) solution obtained by repea…


[Phys. Rev. A 105, 062440] Published Thu Jun 23, 2022

Categories: Journals, Physics

Optical control of the complex phase of a quantum ground-state amplitude

Thu, 2022-06-23 12:00

Author(s): Adam Kinos, Mogens Dalgaard, and Klaus Mølmer

We discuss how coherent driving of a two-level quantum system can be used to induce a complex phase on the ground state and we discuss its geometric and dynamic contributions. While the global phase of a wave function has no physical significance, the coherent dynamics in a two-level subspace provid…


[Phys. Rev. A 105, 062441] Published Thu Jun 23, 2022

Categories: Journals, Physics

Nonlinear quantum error correction

Wed, 2022-06-22 12:00

Author(s): Maximilian Reichert, Louis W. Tessler, Marcel Bergmann, Peter van Loock, and Tim Byrnes

We introduce a theory of quantum error correction (QEC) for a subclass of states. In the standard theory of QEC, the set of all encoded states is formed by an arbitrary linear combination of the codewords. However, this can be more general than required for a given quantum protocol which may only tr…


[Phys. Rev. A 105, 062438] Published Wed Jun 22, 2022

Categories: Journals, Physics

Tensor-network discriminator architecture for classification of quantum data on quantum computers

Wed, 2022-06-22 12:00

Author(s): Michael L. Wall, Paraj Titum, Gregory Quiroz, Michael Foss-Feig, and Kaden R. A. Hazzard

We demonstrate the use of matrix product state (MPS) models for discriminating quantum data on quantum computers using holographic algorithms, focusing on the problem of classifying a translationally invariant quantum state based on L qubits of quantum data extracted from it. We detail a process in …


[Phys. Rev. A 105, 062439] Published Wed Jun 22, 2022

Categories: Journals, Physics

Optimal supplier of single-error-type entanglement via coherent-state transmission

Tue, 2022-06-21 12:00

Author(s): Koji Azuma, Nobuyuki Imoto, and Masato Koashi

Compared with entanglement with multiple types of noise, entanglement including only one type of error is a favorable fundamental resource not only for quantum communication but also for distributed quantum computation. We consider protocols that present single-error-type entanglement for distant qu…


[Phys. Rev. A 105, 062432] Published Tue Jun 21, 2022

Categories: Journals, Physics

Thermodynamic length and work optimization for Gaussian quantum states

Tue, 2022-06-21 12:00

Author(s): Mohammad Mehboudi and Harry J. D. Miller

Constructing optimal thermodynamic processes in quantum systems relies on managing the balance between the average excess work and its stochastic fluctuations. Recently it has been shown that two different quantum generalizations of thermodynamic length can be utilized to determine protocols with ei…


[Phys. Rev. A 105, 062434] Published Tue Jun 21, 2022

Categories: Journals, Physics

Quantum and classical annealing in a continuous space with multiple local minima

Tue, 2022-06-21 12:00

Author(s): Yang Wei Koh and Hidetoshi Nishimori

The protocol of quantum annealing is applied to an optimization problem with a one-dimensional continuous degree of freedom, a variant of the problem proposed by Shinomoto and Kabashima. The energy landscape has a number of local minima, and the classical approach of simulated annealing is predicted…


[Phys. Rev. A 105, 062435] Published Tue Jun 21, 2022

Categories: Journals, Physics

Single-step implementation of a hybrid controlled-<span class="sc">not</span> gate with one superconducting qubit simultaneously controlling multiple target cat-state qubits

Tue, 2022-06-21 12:00

Author(s): Qi-Ping Su, Yu Zhang, and Chui-Ping Yang

Hybrid quantum gates have recently drawn considerable attention. They play significant roles in connecting quantum information processors with qubits of different encoding and have important applications in the transmission of quantum states between a quantum processor and a quantum memory. In this …


[Phys. Rev. A 105, 062436] Published Tue Jun 21, 2022

Categories: Journals, Physics

Efficiency of photonic state tomography affected by fiber attenuation

Tue, 2022-06-21 12:00

Author(s): Artur Czerwinski and Jakub Szlachetka

In this article, we investigate the efficiency of photonic state tomography in the presence of fiber attenuation. The theoretical formalism of the photon loss is provided by implementing methods from the theory of open quantum systems. The quantum state is reconstructed from photon counts obtained f…


[Phys. Rev. A 105, 062437] Published Tue Jun 21, 2022

Categories: Journals, Physics

Straddling-gates problem in multipartite quantum systems

Fri, 2022-06-17 12:00

Author(s): Yuxuan Zhang

We study a variant of quantum circuit complexity, the binding complexity: Consider an n-qubit system divided into two sets of k1, k2 qubits each (k1≤k2) and gates within each set are free; what is the least cost of two-qubit gates “straddling” the sets for preparing an arbitrary quantum state, assum…


[Phys. Rev. A 105, 062430] Published Fri Jun 17, 2022

Categories: Journals, Physics

Statistical complexity of quantum circuits

Fri, 2022-06-17 12:00

Author(s): Kaifeng Bu, Dax Enshan Koh, Lu Li, Qingxian Luo, and Yaobo Zhang

In theoretical machine learning, the statistical complexity is a notion that measures the richness of a hypothesis space. In this work, we apply a particular measure of statistical complexity, namely, the Rademacher complexity, to the quantum circuit model in quantum computation and study how the st…


[Phys. Rev. A 105, 062431] Published Fri Jun 17, 2022

Categories: Journals, Physics