QUROPE Quantum Information Processing and Communication in Europe

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): Gabriel M. Lando, Olivier Giraud, and Denis Ullmo

We study the time evolution of mean values of quantum operators in a regime plagued by two difficulties: the smallness of ℏ and the presence of strong and ubiquitous classical chaos. While numerics become too computationally expensive for purely quantum calculations as ℏ→0, methods that take advanta…

[Phys. Rev. Lett. 132, 260401] Published Wed Jun 26, 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): M. Cristina Volpe

Neutrinos can change flavors due to their nonzero masses and mixings as well as their interactions with matter and other neutrinos. In dense astrophysical environments, such as core-collapse supernovae or neutron star mergers, the problem of neutrino flavor evolution becomes very complex. Connections to other domains such as quantum information theory have been uncovered. Understanding the neutrino flavor evolution in dense environments can shed light on the dynamics of massive star explosions and the origin of heavy elements in the Universe and is important for future observations of supernova neutrinos.

[Rev. Mod. Phys. 96, 025004] Published Mon Jun 24, 2024

Author(s): Elisabeth Kreuzgruber, Richard Wagner, Niels Geerits, Hartmut Lemmel, and Stephan Sponar

Leggett-Garg inequalities (LGIs) have been proposed in order to assess how far the predictions of quantum mechanics defy “macroscopic realism.” With LGIs, correlations of measurements performed on a single system at different times are described. We report on an experiment that demonstrates the viol…

[Phys. Rev. Lett. 132, 260201] Published Mon Jun 24, 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): Subhendu B. Ghosh, Snehasish Roy Chowdhury, Guruprasad Kar, Arup Roy, Tamal Guha, and Manik Banik

Quantum nonlocality, pioneered in Bell’s seminal work and subsequently verified through a series of experiments, has drawn substantial attention due to its practical applications in various protocols. Evaluating and comparing the extent of nonlocality within distinct quantum correlations holds signi…

[Phys. Rev. Lett. 132, 250205] Published Fri Jun 21, 2024

Author(s): Alessandro Foligno, Pavel Kos, and Bruno Bertini

We study the spreading of quantum information in a recently introduced family of brickwork quantum circuits that generalizes the dual-unitary class. These circuits are unitary in time, while their spatial dynamics is unitary only in a restricted subspace. First, we show that local operators spread a…

[Phys. Rev. Lett. 132, 250402] Published Fri Jun 21, 2024

Author(s): Jing Yang

The postselected quantum metrological scheme is especially advantageous when the final measurements are either very noisy or expensive in practical experiments. In this Letter, we put forward a general theory on the compression channels in postselected quantum metrology. We define the basic notions …

[Phys. Rev. Lett. 132, 250802] Published Fri Jun 21, 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): Kangyuan Yi, Yong-Ju Hai, Kai Luo, Ji Chu, Libo Zhang, Yuxuan Zhou, Yao Song, Song Liu, Tongxing Yan, Xiu-Hao Deng, Yuanzhen Chen, and Dapeng Yu

As quantum circuits become more integrated and complex, additional error sources that were previously insignificant start to emerge. Consequently, the fidelity of quantum gates benchmarked under pristine conditions falls short of predicting their performance in realistic circuits. To overcome this p…

[Phys. Rev. Lett. 132, 250604] Published Thu Jun 20, 2024

Author(s): Ke Zeng, Xiaohui Yu, Martin B. Plenio, and Zhen-Yu Wang

We present a quantum sensing technique that utilizes a sequence of π pulses to cyclically drive the qubit dynamics along a geodesic path of adiabatic evolution. This approach effectively suppresses the effects of both decoherence noise and control errors while simultaneously removing unwanted resona…

[Phys. Rev. Lett. 132, 250801] Published Thu Jun 20, 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

Author(s): Yin Mo, Chengkai Zhu, Zhiping Liu, Mingrui Jing, and Xin Wang

In quantum computing, the nonstabilizerness of quantum operations is crucial for understanding and quantifying quantum speedups. In this study, we explore the phenomena of nonstabilizerness of the quantum SWITCH, a novel structure that allows quantum states to pass through operations in a superposit…

[Phys. Rev. A 109, 062428] Published Thu Jun 20, 2024