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Assessing the quality of an ensemble of noisy entangled states is a central task in quantum information processing. Usually this is done by measuring and hence destroying multiple copies, from which state tomography or fidelity estimation…

Quantum Physics · Physics 2023-02-14 Ferran Riera-Sàbat , Jorge Miguel-Ramiro , Wolfgang Dür

Entanglement constitutes a key characteristic feature of quantum matter. Its detection, however, still faces major challenges. In this letter, we formulate a framework for probing entanglement based on machine learning techniques. The…

Quantum Physics · Physics 2021-08-18 Jun Yong Khoo , Markus Heyl

Using extensive numerical analysis of 20,000 randomly generated two-qubit states, we provide a quantitative analysis of the connection between entanglement measures and Maximized Quantum Fisher Information (MQFI). Our systematic study shows…

Quantum Physics · Physics 2025-10-03 Volkan Erol

The expected indefinite causal structure in quantum gravity poses a challenge to the notion of entanglement: If two parties are in an indefinite causal relation of being spacelike and timelike, can they still be entangled? If so, how does…

Quantum Physics · Physics 2018-02-27 Ding Jia

Negativity is regarded as an important measure of entanglement in quantum information theory. In contrast to other measures of entanglement, it is easily computable for bipartite states in arbitrary dimensions. In this paper, based on the…

Quantum Physics · Physics 2010-04-30 Yong-Cheng Ou , Mark S. Byrd

Quantum state preparation is an important subroutine in many quantum algorithms. The goal is to encode classical information directly to the quantum state so that it is possible to leverage quantum algorithms for data processing. However,…

Quantum Physics · Physics 2026-05-01 Oskari Kerppo , William Steadman , Ossi Niemimäki , Valtteri Lahtinen

We introduce a measure of both quantum as well as classical correlations in a quantum state, the entanglement of purification. We show that the (regularized) entanglement of purification is equal to the entanglement cost of creating a state…

Quantum Physics · Physics 2009-11-07 Barbara M. Terhal , Michal Horodecki , Debbie W. Leung , David P. DiVincenzo

Despite their importance in quantum theory, joint quantum measurements remain poorly understood. An intriguing conceptual and practical question is whether joint quantum measurements on separated systems can be performed without bringing…

Quantum Physics · Physics 2025-12-23 Jef Pauwels , Alejandro Pozas-Kerstjens , Flavio Del Santo , Nicolas Gisin

We show that entanglement of pure multi-party states can be quantified by means of quantum uncertainties of certain basic observables through the use of measure that has been initially proposed in [10] for bipartite systems.

Quantum Physics · Physics 2016-08-16 Alexander A. Klyachko , Barış Öztop , Alexander S. Shumovsky

We present conditions every measure of entanglement has to satisfy and construct a whole class of 'good' entanglement measures. The generalization of our class of entanglement measures to more than two particles is straightforward. We…

Quantum Physics · Physics 2009-01-23 V. Vedral , M. B. Plenio , M. A. Rippin , P. L. Knight

In studies of entanglement, finding out if a state is entangled and quantifying the amount of entanglement contained in a state are related but different questions. Similarly in studies of causality, finding out the causal structures…

Quantum Physics · Physics 2018-01-22 Ding Jia

The notion of entanglement of quantum states is usually defined with respect to a fixed bipartition. Indeed, a global basis change can always map an entangled state to a separable one. The situation is however different when considering a…

Quantum Physics · Physics 2021-06-02 Yu Cai , Baichu Yu , Pooja Jayachandran , Nicolas Brunner , Valerio Scarani , Jean-Daniel Bancal

We study the entanglement between a certain qubit and the remaining system in rank- 2 mixed states prepared on the quantum computer. The protocol, which we propose for this purpose, is based on the relation of geometric measure of…

Quantum Physics · Physics 2021-05-24 A. R. Kuzmak , V. M. Tkachuk

The measurement precision of modern quantum simulators is intrinsically constrained by the limited set of measurements that can be efficiently implemented on hardware. This fundamental limitation is particularly severe for quantum…

Quantum Physics · Physics 2020-07-01 Giacomo Torlai , Guglielmo Mazzola , Giuseppe Carleo , Antonio Mezzacapo

We propose to detect quantum entanglement by a condition of local measurments. We find that this condition can detect efficiently the pure entangled states for both discrete and continuous variable systems. It does not depend on…

Quantum Physics · Physics 2015-05-30 Qing Xie , X. -X. Wu , X. -M. Ding , W. -L. Yang , R. -H. Yue , H. Fan

Characterizing entanglement in all but the simplest case of a two qubit pure state is a hard problem, even understanding the relevant experimental quantities that are related to entanglement is difficult. It may not be necessary, however,…

Quantum Physics · Physics 2015-06-26 J. Grondalski , D. M. Etlinger , D. F. V. James

In this paper, we present a thought experiment that demonstrates that the equivalence of quantum reduced states and statistical mixed states of ensembles is not merely a simple mathematical formulation in quantum mechanics, but rather…

Quantum Physics · Physics 2025-04-18 Zhihong Zuo

We propose and develop a new procedure, whereby a quantum system can learn to anneal to a desired ground state. We demonstrate successful learning to produce an entangled state for a two-qubit system, then demonstrate generalizability to…

Quantum Physics · Physics 2017-04-27 E. C. Behrman , J. E. Steck , M. A. Moustafa

The achievement of quantum supremacy boosted the need for a robust medium of quantum information. In this task, higher-dimensional qudits show remarkable noise tolerance and enhanced security for quantum key distribution applications.…

The efficient generation of high-fidelity entangled states is the key element for long-distance quantum communication, quantum computation and other quantum technologies, and at the same time the most resource-consuming part in many…

Quantum Physics · Physics 2021-07-28 Ferran Riera Sàbat , Pavel Sekatski , Alexander Pirker , Wolfgang Dür