QUROPE Quantum Information Processing and Communication in Europe

Author(s): Kan Takase, Fumiya Hanamura, Hironari Nagayoshi, J. Eli Bourassa, Rafael N. Alexander, Akito Kawasaki, Warit Asavanant, Mamoru Endo, and Akira Furusawa

The generation of a logical qubit called the Gottesman-Kitaev-Preskill (GKP) qubit in an optical traveling wave is a major challenge for realizing large-scale universal fault-tolerant optical quantum computers. Recently, probabilistic generation of elementary GKP qubits has been demonstrated using p…

[Phys. Rev. A 110, 012436] Published Fri Jul 12, 2024

Author(s): Akshay Seshadri, Martin Ringbauer, Jacob Spainhour, Rainer Blatt, Thomas Monz, and Stephen Becker

As quantum devices become more complex and the requirements on these devices become more demanding, it is crucial to be able to verify the performance of such devices in a scalable and reliable fashion. A cornerstone task in this challenge is quantifying how close an experimentally prepared quantum …

[Phys. Rev. Lett. 133, 020402] Published Wed Jul 10, 2024

Author(s): Christian Bertoni, Jonas Haferkamp, Marcel Hinsche, Marios Ioannou, Jens Eisert, and Hakop Pashayan

We provide practical and powerful schemes for learning properties of a quantum state using a small number of measurements. Specifically, we present a randomized measurement scheme modulated by the depth of a random quantum circuit in one spatial dimension. This scheme interpolates between two known …

[Phys. Rev. Lett. 133, 020602] Published Wed Jul 10, 2024

Author(s): Pingal Pratyush Nath, Debashis Saha, Dipankar Home, and Urbasi Sinha

We theoretically formulate and experimentally demonstrate a secure scheme for semi-device-independent quantum random number generation by utilizing Leggett-Garg inequality violations, within a loophole-free photonic architecture. The quantification of the generated randomness is rigorously estimated…

[Phys. Rev. Lett. 133, 020802] Published Wed Jul 10, 2024

Author(s): Akshay Seshadri, Martin Ringbauer, Jacob Spainhour, Thomas Monz, and Stephen Becker

Estimating the fidelity with a target state is important in quantum information tasks. Many fidelity-estimation techniques present a suitable measurement scheme to perform the estimation. In contrast, we present techniques that allow the experimentalist to choose a convenient measurement setting. Ou…

[Phys. Rev. A 110, 012431] Published Wed Jul 10, 2024

Author(s): Shuyue Wang, Wuji Zhang, Chunfang Sun, Chunfeng Wu, and Gangcheng Wang

In this study we engineer the z component of the Dzyaloshinskii-Moriya interaction mediated by photons to emulate ground-state chiral excitation based on three-level atoms driven by quantum and classical fields. We employ adiabatic elimination techniques to derive an effective Dzyaloshinskii-Moriya …

[Phys. Rev. A 110, 012432] Published Wed Jul 10, 2024

Author(s): Francesco Campaioli, Stefano Gherardini, James Q. Quach, Marco Polini, and Gian Marcello Andolina

Storage of energy in quantum devices is of practical relevance for applications in quantum technologies. The topic attracts attention also of a more foundational character due to the possibility that the charging power and work extraction can benefit from quantum coherence and collective effects. This Colloquium reviews theoretical concepts and experimental implementations of energy storage in quantum batteries drawing on work in quantum thermodynamics and quantum information science.

[Rev. Mod. Phys. 96, 031001] Published Tue Jul 09, 2024

Author(s): Maxwell Aifer, Juzar Thingna, and Sebastian Deffner

Quantum synchronization is crucial for understanding complex dynamics and holds potential applications in quantum computing and communication. Therefore, assessing the thermodynamic resources required for finite-time synchronization in continuous-variable systems is a critical challenge. In the pres…

[Phys. Rev. Lett. 133, 020401] Published Tue Jul 09, 2024

Author(s): Yuexun Huang, Francisco Salces–Carcoba, Rana X. Adhikari, Amir H. Safavi-Naeini, and Liang Jiang

The vacuum beam guide (VBG) presents a completely different solution for quantum channels to overcome the limitations of existing fiber and satellite technologies for long-distance quantum communication. With an array of aligned lenses spaced kilometers apart, the VBG offers ultrahigh transparency o…

[Phys. Rev. Lett. 133, 020801] Published Tue Jul 09, 2024

Author(s): Abdul Basit, Hamad Ali, Gao Xianlong, Peng-Bo Li, Gehad Sadiek, and Hichem Eleuch

The entropic uncertainty relation imposes a limit on the accuracy of measurement outcomes of two conjugate observables, which can be reduced in the presence of quantum memory. We theoretically study the dynamical behaviors of the quantum-memory-assisted entropic uncertainty relation for a bipartite …

[Phys. Rev. A 110, 012429] Published Tue Jul 09, 2024

Author(s): Peter Brearley and Sylvain Laizet

A quantum algorithm for solving the advection equation by embedding the discrete time-marching operator into Hamiltonian simulations is presented. One-dimensional advection can be simulated directly since the central finite-difference operator for first-order derivatives is anti-Hermitian. Here this…

[Phys. Rev. A 110, 012430] Published Tue Jul 09, 2024

Author(s): Mingjian He and Shouyin Liu

Continuous variable quantum teleportation provides a path to the long-distance transmission of quantum states. Photon-varying non-Gaussian operations have been shown to improve the fidelity of quantum teleportation when integrated into the protocol. However, for a given type of non-Gaussian operatio…

[Phys. Rev. A 110, 012425] Published Tue Jul 09, 2024

Author(s): P. Z. Zhao and Jiangbin Gong

Nonadiabatic holonomic operations are based on nonadiabatic non-Abelian geometric phases, hence possessing the inherent geometric features for robustness against control errors. However, nonadiabatic holonomic operations are still sensitive to the systematic amplitude error induced by imperfect cont…

[Phys. Rev. A 110, 012426] Published Tue Jul 09, 2024

Author(s): Mingzhao Liu (刘铭钊) and Charles T. Black

This paper presents a computational analysis of a superconducting transmon qubit design, in which the superconductor-insulator-superconductor (SIS) Josephson junction is replaced by a coplanar, superconductor-constriction-superconductor (ScS) nanobridge junction. Within the scope of Ginzburg-Landau …

[Phys. Rev. A 110, 012427] Published Tue Jul 09, 2024

Author(s): Ernesto Campos, Daniil Rabinovich, and Alexey Uvarov

Variational quantum algorithms have become the de facto model for current quantum computations. A prominent example of such algorithms—the quantum approximate optimization algorithm (QAOA)—was originally designed for combinatorial optimization tasks, but has been shown to be successful for a variety…

[Phys. Rev. A 110, 012428] Published Tue Jul 09, 2024

Author(s): Dominik Hangleiter and Michael J. Gullans

A central challenge in the verification of quantum computers is benchmarking their performance as a whole and demonstrating their computational capabilities. In this Letter, we find a universal model of quantum computation, Bell sampling, that can be used for both of those tasks and thus provides an…

[Phys. Rev. Lett. 133, 020601] Published Mon Jul 08, 2024

Author(s): Shuyang Meng, Fionnuala Curran, Gabriel Senno, Victoria J. Wright, Máté Farkas, Valerio Scarani, and Antonio Acín

Quantum states possess an intrinsic form of randomness, inaccessible even to an all-powerful eavesdropper. The authors find concise mathematical expressions for the maximal intrinsic randomness that can be extracted from any quantum state, as quantified by the conditional min-, von Neumann and max-entropies. They also characterize the optimal (and inequivalent) measurements in each case.

[Phys. Rev. A 110, L010403] Published Mon Jul 08, 2024

Author(s): Dávid Pataki, Áron Márton, János K. Asbóth, and András Pályi

Quantum error correction is a key challenge for the development of practical quantum computers, a direction in which significant experimental progress has been made in recent years. In solid-state qubits, one of the leading information loss mechanisms is dephasing, usually modeled by phase-flip erro…

[Phys. Rev. A 110, 012417] Published Mon Jul 08, 2024

Author(s): Li-Juan Li, Xiao Gang Fan, Xue-Ke Song, Liu Ye, and Dong Wang

Quantum steering is considered one of the most well-known nonlocal phenomena in quantum mechanics. Unlike entanglement and Bell nonlocality, the asymmetry of quantum steering makes it vital for one-sided device-independent quantum information processing. Although there has been much progress on stee…

[Phys. Rev. A 110, 012418] Published Mon Jul 08, 2024

Author(s): Prithviraj Prabhu and Ben W. Reichardt

When storing encoded qubits, if single faults can be corrected and double faults can be postselected against, logical errors occur due to at least three faults. At current noise rates, having to restart when two errors are detected prevents very long-term storage, but that should not be an issue for…

[Phys. Rev. A 110, 012419] Published Mon Jul 08, 2024