QUROPE Quantum Information Processing and Communication in Europe

Author(s): Si-Yuan Qi, Geni Gupur, Yu-Chun Wu, and Guo-Ping Guo

Equivalence between positive partial transpose (PPT) entanglement and bound entanglement is a long-standing open problem in quantum information theory. Limited progress has been made so far, even on the seemingly simple case of the bound entanglement of Werner states. The primary challenge is to giv…

[Phys. Rev. A 110, 012406] Published Mon Jul 01, 2024

Author(s): Paweł Cieśliński, Paweł Kurzyński, Tomasz Sowiński, Waldemar Kłobus, and Wiesław Laskowski

The investigation of many-body interactions holds significant importance for both quantum foundations and information. Hamiltonians coupling multiple particles at once, beyond other applications, can lead to faster entanglement generation, multiqubit gate implementation, and improved error correctio…

[Phys. Rev. A 110, 012407] Published Mon Jul 01, 2024

Author(s): Anaelle Hertz, Aaron Z. Goldberg, and Khabat Heshami

The quadrature coherence scale (QCS) is a recently introduced measure that was shown to be an efficient witness of nonclassicality. It takes a simple form for pure and Gaussian states, but a general expression for mixed states tends to be prohibitively unwieldy. In this paper we introduce a method f…

[Phys. Rev. A 110, 012408] Published Mon Jul 01, 2024

Author(s): Yudai Suzuki and Muyuan Li

Quantum kernel methods have been actively examined from both theoretical and practical perspectives due to the potential of quantum advantage in machine learning tasks. Despite a provable advantage of fine-tuned quantum kernels for specific problems, widespread practical usage of quantum kernel meth…

[Phys. Rev. A 110, 012409] Published Mon Jul 01, 2024

Author(s): Sudipta Das, Rivu Gupta, Himadri Shekhar Dhar, and Aditi Sen(De)

The telecloning protocol distributes quantum states from a single sender to multiple receivers via a shared entangled state by exploiting the notions of teleportation and approximate cloning. We investigate the optimal telecloning fidelities obtained using both Gaussian and non-Gaussian shared resou…

[Phys. Rev. A 110, 012410] Published Mon Jul 01, 2024

Author(s): Huan Zhang, Ying Xia, Wei Ye, Shoukang Chang, and Zeyang Liao

Quantum illumination is a quantum sensing protocol primarily used for object detection, which aims to detect the presence of a target with low reflectivity in the free space using quantum light fields. Here we investigate a quantum illumination scheme using an entangled light source by performing no…

[Phys. Rev. A 109, 062440] Published Fri Jun 28, 2024

Author(s): Daniel Honciuc Menendez, Annie Ray, and Michael Vasmer

Quantum computers promise to solve problems that are intractable for classical computers, but qubits are vulnerable to many sources of error, limiting the depth of the circuits that can be reliably executed on today's quantum hardware. Quantum error correction has been proposed as a solution to this…

[Phys. Rev. A 109, 062438] Published Fri Jun 28, 2024

Author(s): B. Sharmila, F. M. Souza, H. M. Vasconcelos, and L. Sanz

We investigate the generation of an entangled electron pair emerging from a system composed of two quantum dots attached to a superconductor Cooper-pair beam splitter. We take into account three processes: crossed Andreev reflection, cotunneling, and Coulomb interaction. Together, these processes pl…

[Phys. Rev. A 109, 062439] Published Fri Jun 28, 2024

Author(s): Ryan J. Marshman, Deepesh Singh, Timothy C. Ralph, and Austin P. Lund

We consider the impact of the unitary-averaging framework on single- and two-mode linear optical gates. We demonstrate that this allows a trade-off between the probability of success and gate fidelity, with perfect fidelity gates being achievable for a finite decrease in the probability of success, …

[Phys. Rev. A 109, 062436] Published Thu Jun 27, 2024

Author(s): Baptiste Anselme Martin, Thomas Ayral, François Jamet, Marko J. Rančić, and Pascal Simon

Matrix product states (MPSs) and matrix product operators (MPOs) have been proven to be a powerful tool to study quantum many-body systems but are restricted to moderately entangled states as the number of parameters scales exponentially with the entanglement entropy. While MPSs can efficiently find…

[Phys. Rev. A 109, 062437] Published Thu Jun 27, 2024

Author(s): Yi Tao, Ting Chen, Hongyang Wang, Jie Zhang, Ting Zhang, Yi Xie, Pingxing Chen, and Wei Wu

In a trapped-ion system, accurate thermometry of ions is crucial for precisely evaluating the system state and performing quantum operations. However, when the motional state of a single ion is far away from the ground state, the spatial dimensionality of the phonon state sharply increases. Then it …

[Phys. Rev. A 109, 062434] Published Tue Jun 25, 2024

Author(s): Raphaël Mothe, Cyril Branciard, and Alastair A. Abbott

The quantum switch, the canonical example of a process with indefinite causal order, has been claimed to provide various advantages over processes with definite causal orders for some particular tasks in the field of quantum metrology. In this work, we argue that some of these advantages in fact do …

[Phys. Rev. A 109, 062435] Published Tue Jun 25, 2024

Author(s): Chien-Hung Cho, Dominic W. Berry, and Min-Hsiu Hsieh

Hamiltonian simulation is a major application of quantum computing, for example, enabling prediction of the properties of molecules. Prior work has used product formulas with randomization to improve performance, but has only yielded modest improvements over the excellent performance provided by det…

[Phys. Rev. A 109, 062431] Published Mon Jun 24, 2024

Author(s): Ole Sönnerborn

Nonadiabatic holonomic quantum computation has been proposed as a method to implement quantum logic gates with robustness comparable to that of adiabatic holonomic gates but with shorter execution times. In this paper, we establish an isoholonomic inequality for quantum gates, which provides a lower…

[Phys. Rev. A 109, 062433] Published Mon Jun 24, 2024

Author(s): Suirong He, Penghui Ouyang, Haiyan Gao, Yufen Li, Jiaxing He, and L. F. Wei

Microwave single-photon detection is one of the critical tasks for the implementation of the desired microwave quantum information processing. Given the detection efficiency of the demonstrated microwave single-photon detector is still very limited, here, we propose a nonreciprocity detector array t…

[Phys. Rev. A 109, 062430] Published Mon Jun 24, 2024

Author(s): Fang-Mei Yang and Fu-Quan Dou

Quantum batteries (QBs) are energy storage and transfer microdevices that open up new possibilities in energy technology. Here, we derive a resonator–multiple-qutrit quantum battery (QB) model consisting of a multimode resonator and N superconducting transmon qutrits. We investigate the charging and…

[Phys. Rev. A 109, 062432] Published Mon Jun 24, 2024

Author(s): David R. M. Arvidsson-Shukur, Crispin H. W. Barnes, Hugo V. Lepage, Seth Lloyd, Noah Lupu-Gladstein, Wilfred Salmon, and Flavio Salvati

In a recent paper [Das, Modak, and Bera, Phys. Rev. A 107, 042413 (2023)], Das et al. claim that Kirkwood-Dirac negativity is not required to achieve anomalous values of the quantum Fisher information encoded in postselected (filtered) particles. We argue that this claim is wrong. Further, we show t…

[Phys. Rev. A 109, 066401] Published Fri Jun 21, 2024

Author(s): Sourav Das, Subhrajit Modak, and Manabendra Nath Bera

In Das et al. [Phys. Rev. A 107, 042413 (2023)], we showed that Kirkwood-Dirac negativity is not necessary to achieve anomalous quantum Fisher information. Arvidsson-Shukur et al. [preceding Comment, Phys. Rev. A (to be published)] claim that one of our conclusions is wrong. Here, we argue that the …

[Phys. Rev. A 109, 066402] Published Fri Jun 21, 2024

Author(s): Liubov Markovich, Savvas Malikis, Stefano Polla, and Jordi Tura

Parameter shift rules enable the estimation of the derivatives of expectation values with respect to the dynamical evolution of a state. Thus, they provide a valuable tool in variational optimization and insight into the dynamical behavior of quantum systems. Constructing parameter shift rules appli…

[Phys. Rev. A 109, 062429] Published Fri Jun 21, 2024

Author(s): Xue Yang, Yan-Han Yang, Shao-Ming Fei, and Ming-Xing Luo

The presence of quantum multipartite entanglement implies the existence of a thermodynamic quantity known as the ergotropic gap, which is defined as the difference between the maximal global and local extractable works from the system. We establish a direct relation between the geometric measure of …

[Phys. Rev. A 109, 062427] Published Thu Jun 20, 2024