QUROPE Quantum Information Processing and Communication in Europe

Author(s): Deepesh Singh, Austin P. Lund, and Peter P. Rohde

Cluster states are the essential resource used in the implementation of fusion-based quantum computation (FBQC). We introduce a method to generate high-fidelity optical cluster states by utilizing the concept of unitary averaging. This error-averaging technique is entirely passive and can be readily…

[Phys. Rev. A 110, 012457] Published Wed Jul 24, 2024

Author(s): Hongshun Yao, Xia Liu, Chengkai Zhu, and Xin Wang

Quantum broadcasting is central to quantum information processing and characterizes the correlations within quantum states. Nonetheless, traditional quantum broadcasting encounters inherent limitations dictated by the principles of quantum mechanics. In a previous study, Parzygnat et al. [Phys. Rev.…

[Phys. Rev. A 110, 012458] Published Wed Jul 24, 2024

Author(s): Zhu-yao Jin and Jun Jing

A stable and high-quality single-magnon state is desired by the single-magnon source for quantum-information application with a macroscopic spin system. We consider a hybrid system where a magnon mode is directly coupled to a nonresonant superconducting qubit via the exchange interaction. The magnon…

[Phys. Rev. A 110, 012459] Published Wed Jul 24, 2024

Author(s): Luke Coffman, Akshay Seshadri, Graeme Smith, and Jacob L. Beckey

Despite multipartite entanglement being a global property of a quantum state, a number of recent works have made it clear that it can be quantified using only local measurements. This is appealing because local measurements are the easiest to implement on current quantum hardware. However, it remain…

[Phys. Rev. A 110, 012454] Published Tue Jul 23, 2024

Author(s): Christopher F. Kane, Niladri Gomes, and Michael Kreshchuk

We present several improvements to the recently developed ground-state preparation algorithm based on the quantum eigenvalue transformation for unitary matrices (QETU), apply this algorithm to a lattice formulation of U(1) gauge theory in (2+1) dimensions, as well as propose an alternative applicati…

[Phys. Rev. A 110, 012455] Published Tue Jul 23, 2024

Author(s): Hai-Jun Xing

The efficiency of quantum measurements in distinguishing neighboring quantum states is a central topic in quantum information sciences. We study the efficiency of vertex measurement in two-parameter estimation from the information geometry perspective, where the vertex measurement is a rare typical …

[Phys. Rev. A 110, 012449] Published Mon Jul 22, 2024

Author(s): Yang-Guang Shan, Yao Zhou, Zhen-Qiang Yin, Shuang Wang, Wei Chen, De-Yong He, Guang-Can Guo, and Zheng-Fu Han

Twin-field (TF) quantum key distribution (QKD) has been extensively researched because of its long transmission distance. The phase-encoding TF-QKD can realize both a high key rate and a long transmission distance, so it has attracted a lot of attention. In this article, we are inspired by the sendi…

[Phys. Rev. A 110, 012450] Published Mon Jul 22, 2024

Author(s): Ahana Ghoshal and Ujjwal Sen

We obtain a Gorini-Kossakowski-Sudarshan-Lindblad-like master equation for two or more quantum systems connected locally to a combination of Markovian and non-Markovian heat baths. The master equation was originally formulated for multiparty systems with either exclusively Markovian or non-Markovian…

[Phys. Rev. A 110, 012451] Published Mon Jul 22, 2024

Author(s): Xuanran Zhu, Chao Zhang, and Bei Zeng

Determining whether a subspace spanned by certain quantum states is entangled and its entanglement dimensionality remains a fundamental challenge in quantum information science. This paper introduces a geometric measure of r-bounded rank, Er(S), for a given subspace S. Derived from the established g…

[Phys. Rev. A 110, 012452] Published Mon Jul 22, 2024

Author(s): Shilin Huang and Shruti Puri

Quantum error correction (QEC) with single-shot decoding enables the reduction of errors after every single round of noisy stabilizer measurement, easing the time-overhead requirements for fault tolerance. Notably, several classes of quantum low-density parity check (qLDPC) codes are known which fac…

[Phys. Rev. A 110, 012453] Published Mon Jul 22, 2024

Author(s): Rui Li, Junling Du, Zheng Qin, Shikun Zhang, Chunxiao Du, Yang Zhou, and Zhisong Xiao

Quantum entanglement plays a pivotal role in various quantum information processing tasks. However, a universal and effective way to detect entanglement structures is still lacking, especially for high-dimensional and multipartite quantum systems. Noticing the mathematical similarities between the c…

[Phys. Rev. A 110, 012448] Published Fri Jul 19, 2024

Author(s): Gekko Budiutama, Shunsuke Daimon, Hirofumi Nishi, Ryui Kaneko, Tomi Ohtsuki, and Yu-ichiro Matsushita

Quantum convolutional neural networks (QCNNs) have gathered attention as one of the most promising algorithms for quantum machine learning. Reduction in the cost of training as well as improvement in performance are required for practical implementation of these models. In this study, we propose a c…

[Phys. Rev. A 110, 012447] Published Fri Jul 19, 2024

Author(s): Mirko Consiglio, Jacopo Settino, Andrea Giordano, Carlo Mastroianni, Francesco Plastina, Salvatore Lorenzo, Sabrina Maniscalco, John Goold, and Tony J. G. Apollaro

The preparation of an equilibrium thermal state of a quantum many-body system on noisy intermediate-scale quantum (NISQ) devices is an important task in order to extend the range of applications of quantum computation. Faithful Gibbs state preparation would pave the way to investigate protocols such…

[Phys. Rev. A 110, 012445] Published Thu Jul 18, 2024

Author(s): Göktuğ Karpat and Barış Çakmak

We examine the emergence of dynamical memory effects in quantum processes having indefinite time direction and causal order. In particular, we focus on the class of phase-covariant qubit channels, which encompasses some of the most significant paradigmatic open quantum system models. In order to ass…

[Phys. Rev. A 110, 012446] Published Thu Jul 18, 2024

Author(s): Rajdeep Paul, Souradeep Sasmal, and A. K. Pan

Self-testing protocols refer to novel device-independent certification schemes wherein the devices are uncharacterized and the dimension of the system remains unspecified. The optimal quantum violation of Bell's inequality facilitates such self-testing. In this work we put forth a protocol for self-…

[Phys. Rev. A 110, 012444] Published Wed Jul 17, 2024

Author(s): Ivan Medina, Alexandre Drinko, Guilherme I. Correr, Pedro C. Azado, and Diogo O. Soares-Pinto

The energy extraction from quantum sources is a key task to develop new quantum devices such as quantum batteries (QB). In this context, one of the main figures of merit is the ergotropy, which measures the maximal amount of energy (as work) that can be extracted from the quantum source by means of …

[Phys. Rev. A 110, 012443] Published Wed Jul 17, 2024

Author(s): Eyal Buks

Multistability is experimentally observed in a variety of quantum systems but cannot be derived from any theoretical model that is based on a monostable master equation. The author investigates the relation between disentanglement and multistability in the few-spin transverse Ising model and finds that multistability can be obtained in the presence of spontaneous disentanglement.

[Phys. Rev. A 110, 012439] Published Mon Jul 15, 2024

Author(s): Katarzyna Siudzińska

We use symmetric measurement operators to construct quantum channels that provide a further generalization of generalized Pauli channels. The resulting maps are bistochastic but, in general, no longer mixed unitary. We analyze their important properties, such as complete positivity and the ability t…

[Phys. Rev. A 110, 012440] Published Mon Jul 15, 2024

Author(s): Ming Yang, Dongkai Zhang, and Lixiang Chen

Recent advancements have expanded Hardy's nonlocality arguments into multisetting and multidimensional systems to enhance quantum correlations. In comparison with Hardy's nonlocality argument, Cabello's nonlocality argument (CNA) emerges as a superior choice for illustrating nonlocal features. An op…

[Phys. Rev. A 110, 012441] Published Mon Jul 15, 2024

Author(s): Zi-Jian Xu and Jun-Hong An

Permitting the transmission of unknown quantum states over long distances by using entanglement, quantum teleportation serves as an important building block for many quantum technologies. However, in the noisy intermediate-scale quantum era, the practical realization of quantum teleportation is inev…

[Phys. Rev. A 110, 012442] Published Mon Jul 15, 2024