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Quantum effects in metrology can in principle enhance measurement precision from the so-called standard quantum limit to the Heisenberg Limit. Further advancements in quantum metrology largely rely on innovative metrology protocols that can…

Quantum Physics · Physics 2025-06-16 Zhixing Zou , Jiangbin Gong , Weitao Chen

The representation of a quantum wave function as a neural network quantum state (NQS) provides a powerful variational ansatz for finding the ground states of many-body quantum systems. Nevertheless, due to the complex variational landscape,…

Quantum Physics · Physics 2023-12-06 Eimantas Ledinauskas , Egidijus Anisimovas

Quantum Fisher Information (QFI) sets the ultimate precision limit for parameter estimation and is therefore a central quantity in quantum metrology. In time-dependent many-body systems, however, maximizing QFI is a highly non-trivial task…

In the scenario of the probe-ancilla interaction, we propose a quantum metrology protocol by the unconditional measurement on the ancillary qubit after an optimized period of joint evolution from product state. Its key element is the…

Quantum Physics · Physics 2025-09-12 Peng Chen , Jun Jing

We study optimization programs given by a bilinear form over non-commutative variables subject to linear inequalities. Problems of this form include the entangled value of two-prover games, entanglement-assisted coding for classical…

Quantum Physics · Physics 2016-08-15 Mario Berta , Omar Fawzi , Volkher B. Scholz

To increase efficiency in automotive manufacturing, newly produced vehicles can move autonomously from the production line to the distribution area. This requires an optimal placement of sensors to ensure full coverage while minimizing the…

Emerging Technologies · Computer Science 2025-07-23 Nico Kraus , Marvin Erdmann , Alexander Kuzmany , Daniel Porawski , Jonas Stein

This paper presents a comprehensive exploration of semi-definite programming (SDP) techniques within the context of quantum information. It examines the mathematical foundations of convex optimization, duality, and SDP formulations,…

Quantum Physics · Physics 2024-04-18 Piotr Mironowicz

We study methods to replace entangling operations with random local operations in a quantum computation, at the cost of increasing the number of required executions. First, we consider "space-like cuts" where an entangling unitary is…

Quantum Physics · Physics 2025-01-23 Aram W. Harrow , Angus Lowe

Finding the ground state of a Hamiltonian system is of great significance in many-body quantum physics and quantum chemistry. We propose an improved iterative quantum algorithm to prepare the ground state of a Hamiltonian. The crucial point…

Quantum Physics · Physics 2022-10-25 Jin-Min Liang , Qiao-Qiao Lv , Shu-Qian Shen , Ming Li , Zhi-Xi Wang , Shao-Ming Fei

An efficient method for assessing the quality of quantum state tomography is developed. Special attention is paid to the tomography of multipartite systems in terms of unbiased measurements. Although the overall reconstruction errors of…

Quantum Physics · Physics 2013-11-19 J. Rehacek , Z. Hradil , A. B. Klimov , G. Leuchs , L. L. Sanchez-Soto

Learning the unknown Hamiltonian governing the dynamics of a quantum many-body system is a challenging task. In this manuscript, we propose a possible strategy based on repeated measurements on a single time-dependent state. We prove that…

Quantum Physics · Physics 2023-01-27 Davide Rattacaso , Gianluca Passarelli , Procolo Lucignano

The growing demand for solving large-scale, data-intensive linear and conic optimization problems, particularly in applications such as artificial intelligence and machine learning, has highlighted the limitations of classical interior…

Variational quantum algorithms are promising applications of noisy intermediate-scale quantum (NISQ) computers. These algorithms consist of a number of separate prepare-and-measure experiments that estimate terms in a Hamiltonian. The…

Quantum Physics · Physics 2020-06-25 Andrew Zhao , Andrew Tranter , William M. Kirby , Shu Fay Ung , Akimasa Miyake , Peter Love

Approximate combinatorial optimization is a promising use case for quantum computers. The quantum optimization algorithms often employ a fixed ansatz that evolves an unbiased initial state towards states with better values of the optimand,…

Quantum Physics · Physics 2026-04-30 Phillip C. Lotshaw , Titus Morris , Stuart Hadfield , Ryan Bennink

Reliable preparation of entanglement between distant systems is an outstanding problem in quantum information science and quantum communication. In practice, this has to be accomplished via noisy channels (such as optical fibers) that…

Quantum Physics · Physics 2007-11-01 Liang Jiang , Jacob M. Taylor , Navin Khaneja , Mikhail D. Lukin

We investigate several problems in entanglement theory from the perspective of convex optimization. This list of problems comprises (A) the decision whether a state is multi-party entangled, (B) the minimization of expectation values of…

Quantum Physics · Physics 2009-11-10 J. Eisert , P. Hyllus , O. Guehne , M. Curty

Achieving ultimate bounds in estimation processes is the main objective of quantum metrology. In this context, several problems require measurement of multiple parameters by employing only a limited amount of resources. To this end,…

If only limited control over a multiparticle quantum system is available, a viable method to characterize correlations is to perform random measurements and consider the moments of the resulting probability distribution. We present…

Quantum Physics · Physics 2021-04-23 Satoya Imai , Nikolai Wyderka , Andreas Ketterer , Otfried Gühne

We consider distributed sensing of non-local quantities. We introduce quantum enhanced protocols to directly measure any (scalar) field with a specific spatial dependence by placing sensors at appropriate positions and preparing a spatially…

Quantum Physics · Physics 2020-04-22 Pavel Sekatski , Sabine Wölk , Wolfgang Dür

Given the recent developments in quantum techniques, modeling the physical Hamiltonian of a target quantum many-body system is becoming an increasingly practical and vital research direction. Here, we propose an efficient strategy combining…

Quantum Physics · Physics 2023-06-26 Tian-Lun Zhao , Shi-Xin Hu , Yi Zhang
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