QUROPE Quantum Information Processing and Communication in Europe

Author(s): Peter Sidajaya and Valerio Scarani

As a consequence of Bell's theorem, the statistics of measurements on some entangled states cannot be simulated with local hidden variables alone. The amount of communication that must be supplied is an intuitive quantifier of nonclassicality. While it is obvious that this amount can be very large i…

[Phys. Rev. A 109, 062408] Published Thu Jun 06, 2024

Author(s): Guilherme Zambon and Diogo O. Soares-Pinto

In the dynamics of open quantum systems, information may propagate in time through either the system or the environment, giving rise to Markovian and non-Markovian temporal correlations, respectively. However, despite their notable coexistence in most physical situations, it is not yet clear how the…

[Phys. Rev. A 109, 062401] Published Mon Jun 03, 2024

Author(s): G.-X. Wang, Y.-K. Wu, R. Yao, W.-Q. Lian, Z.-J. Cheng, Y.-L. Xu, C. Zhang, Y. Jiang, Y.-Z. Xu, B.-X. Qi, P.-Y. Hou, Z.-C. Zhou, L. He, and L.-M. Duan

The spin-boson model is a prototypical model for open quantum dynamics. Here we simulate the spin-boson model using a chain of trapped ions in which a spin is coupled to a structured reservoir of bosonic modes. We engineer the spectral density of the reservoir by adjusting the ion number, the target…

[Phys. Rev. A 109, 062402] Published Mon Jun 03, 2024

Author(s): Minjin Choi, Jeonghyeon Shin, Gunho Lee, and Eunok Bae

Quantum teleportation is an essential application of quantum entanglement. The examination of teleportation fidelity in two-party standard teleportation schemes reveals a critical threshold distinguishing separable and entangled states. For separable states, their teleportation fidelities cannot exc…

[Phys. Rev. A 109, 062403] Published Mon Jun 03, 2024

Author(s): Ruidi Zhu, Ciara Pike-Burke, and Florian Mintert

The experimental evaluation of many quantum mechanical quantities requires the estimation of several directly measurable observables, such as local observables. Due to the necessity to repeat experiments on individual quantum systems in order to estimate expectation values of observables, the questi…

[Phys. Rev. A 109, 062404] Published Mon Jun 03, 2024

Author(s): Agung Budiyono

Kirkwood-Dirac (KD) quasiprobability is a quantum analog of classical phase space probability. It offers an informationally complete representation of quantum state wherein the quantumness associated with quantum noncommutativity manifests in its nonclassical values, i.e., the nonreal and/or negativ…

[Phys. Rev. A 109, 062405] Published Mon Jun 03, 2024

Author(s): Yu Wang and Wei Cui

Classical shadow tomography, harnessing randomized informationally complete (IC) measurements, provides an effective avenue for predicting many properties of unknown quantum states. In n-qubit systems, projections onto 2n+1 mutually unbiased bases (MUBs) are widely recognized as minimal and optimal …

[Phys. Rev. A 109, 062406] Published Mon Jun 03, 2024

Author(s): Xian Shi

In this work, we present a coherence measure based on the quantum optimal transport cost in terms of the convex roof extended method. We also obtain the analytical solutions of the quantifier for pure states. We also propose an operational interpretation of the coherence measure for pure states.

[Phys. Rev. A 109, 052443] Published Fri May 31, 2024

Author(s): Christian Ufrecht, Laura S. Herzog, Daniel D. Scherer, Maniraman Periyasamy, Sebastian Rietsch, Axel Plinge, and Christopher Mutschler

Circuit cutting, the partitioning of quantum circuits into smaller independent fragments, has become a promising avenue for scaling up current quantum-computing experiments. Here, we introduce a scheme for joint cutting of two-qubit rotation gates based on a virtual gate-teleportation protocol. With…

[Phys. Rev. A 109, 052440] Published Thu May 30, 2024

Author(s): Yagnik Chatterjee, Eric Bourreau, and Marko J. Rančić

NP-hard problems are not believed to be exactly solvable through general polynomial time algorithms. Hybrid quantum-classical algorithms to address such combinatorial problems have been of great interest in the past few years. Such algorithms are heuristic in nature and aim to obtain an approximate …

[Phys. Rev. A 109, 052441] Published Thu May 30, 2024

Author(s): Bin Liu, Zhonghao Liang, Wei Huang, Fei Gao, Jiayi Yuan, and Bingjie Xu

Quantum private query (QPQ) faces many challenges in practical applications. At present, some scholars have made substantial work on overcoming channel loss, channel noise, and nonideal light sources, respectively. However, a protocol that would overcome all three of these problems has yet to materi…

[Phys. Rev. A 109, 052442] Published Thu May 30, 2024

Author(s): Yingjia Lin, Shilin Huang, and Kenneth R. Brown

For quantum error correction codes the required number of measurement rounds typically increases with the code distance when measurements are faulty. Single-shot error correction allows for an error threshold with only one round of noisy syndrome measurements regardless of the code size. Here we imp…

[Phys. Rev. A 109, 052438] Published Wed May 29, 2024

Author(s): Yuntao Tsui and Sunho Kim

The wave-particle duality, one of the expressions of Bohr complementarity, is usually quantified by path predictability and the visibility of interference fringes. With the development of quantum resource theory, quantitative analysis of wave-particle duality is increasing, most of which are express…

[Phys. Rev. A 109, 052439] Published Wed May 29, 2024

Author(s): Fan Xing, Yan Wei, and Zeyang Liao

Continuous-time quantum walks provide an alternative method for quantum search problems. Most earlier studies confirmed that quadratic speedup exists in some synthetic Hamiltonians, but whether there is quadratic speedup in real physical systems remains elusive. Here, we investigate three physical s…

[Phys. Rev. A 109, 052435] Published Thu May 23, 2024

Author(s): Pratapaditya Bej and Abhishek Banerjee

We study entanglement activation in a generalized entanglement swapping process involving two Bell pairs and generalized measurements. The conventional understanding posits entangled measurements as both necessary and sufficient for establishing entanglement between distant parties. In this study, w…

[Phys. Rev. A 109, 052437] Published Thu May 23, 2024

Author(s): Chun-Mei Zhang, Zhe Wang, Yu-Da Wu, Jian-Rong Zhu, Rong Wang, and Hong-Wei Li

The twin-field quantum key distribution (TF-QKD) protocol and its variants provide promising solutions to long-distance information-theoretic-secure communication, which can surpass the fundamental rate-loss bound without quantum repeaters. Different from other variants, the discrete-phase-randomize…

[Phys. Rev. A 109, 052432] Published Wed May 22, 2024

Author(s): Graziano Amati

We investigate signatures of non-Markovianity in the dynamics of a periodically driven qubit coupled to a dissipative bosonic environment. We propagate the dynamics of the reduced density matrix of the qubit by integrating the numerically exact hierarchical equations of motion. Non-Markovian feature…

[Phys. Rev. A 109, 052433] Published Wed May 22, 2024

Author(s): Zixin Huang, Ben Q. Baragiola, Nicolas C. Menicucci, and Mark M. Wilde

We consider stellar interferometry in the continuous-variable (CV) quantum information formalism and use the quantum Fisher information (QFI) to characterize the performance of three key strategies: direct interferometry (DI), local heterodyne measurement, and a CV teleportation-based strategy. In t…

[Phys. Rev. A 109, 052434] Published Wed May 22, 2024

Author(s): Nora M. Bauer, Rizwanul Alam, George Siopsis, and James Ostrowski

We use quantum imaginary-time evolution (QITE) to solve polynomial unconstrained binary optimization (PUBO) problems. We show that a linear ansatz yields good results for a wide range of PUBO problems, often outperforming standard classical methods, such as the Goemans-Williamson (GW) algorithm. We …

[Phys. Rev. A 109, 052430] Published Tue May 21, 2024

Author(s): Yaroslav Herasymenko, Anurag Anshu, Barbara M. Terhal, and Jonas Helsen

One of the main problems in computational physics is predicting the low-energy behavior of many-body quantum systems. The computational complexity of this problem, however, is relatively poorly understood. A recent major progress in this direction has been the no low-energy trivial states (NLTS) the…

[Phys. Rev. A 109, 052431] Published Tue May 21, 2024