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We propose new entanglement measures as the detection performance based on the hypothesis testing setting. We clarify how our measures work for detecting an entangled state by extending the quantum Sanov theorem. Our analysis covers the…

Quantum Physics · Physics 2025-01-08 Masahito Hayashi , Yuki Ito

Bell-inequality checks constitute a probe of entanglement -- given a source of entangled particles, their violation are a signature of the non-local nature of quantum mechanics. Here, we study a solid state device producing pairs of…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Nikolai M. Chtchelkatchev , Gianni Blatter , Gordey B. Lesovik , Thierry Martin

Entanglement is often verified by a violation of an inequality like a Bell inequality or an entanglement witness. Considerable effort has been devoted to the optimization of such inequalities in order to obtain a high violation. We…

The concept of entanglement witnesses form a useful technique to detect entanglement in realistic quantum devices. Measurement-device-independent nonlinear entanglement witnesses (MDI-NEWs) are a kind of entanglement witnesses which…

Quantum Physics · Physics 2023-12-01 Kornikar Sen , Chirag Srivastava , Ujjwal Sen

We focus on determining the separability of an unknown bipartite quantum state $\rho$ by invoking a sufficiently large subset of all possible entanglement witnesses given the expected value of each element of a set of mutually orthogonal…

Quantum Physics · Physics 2009-11-13 Lawrence M. Ioannou , Benjamin C. Travaglione

It has recently been shown that by broadcasting the subsystems of a bipartite quantum state, one can activate Bell nonlocality and significantly improve noise tolerance bounds for device-independent entanglement certification. In this work…

Nonlocality, manifested by the violation of Bell inequalities, indicates entanglement within a joint quantum system. A natural question is how much entanglement is required for a given nonlocal behavior. Here, we explore this question by…

Quantum Physics · Physics 2025-06-23 Yuwei Zhu , Xingjian Zhang , Xiongfeng Ma

We analyze and compare the mathematical formulations of the criterion for separability for bipartite density matrices and the Bell inequalities. We show that a violation of a Bell inequality can formally be expressed as a witness for…

Quantum Physics · Physics 2009-10-31 Barbara M. Terhal

The human eye can detect optical signals containing only a few photons. We investigate the possibility to demonstrate entanglement with such biological detectors. While one person could not detect entanglement by simply observing photons,…

Quantum Physics · Physics 2013-05-29 Nicolas Brunner , Cyril Branciard , Nicolas Gisin

Standard procedures for entanglement detection assume that experimenters can exactly implement specific quantum measurements. Here, we depart from such idealizations and investigate, in both theory and experiment, the detection of genuine…

Quantum Physics · Physics 2024-10-10 Huan Cao , Simon Morelli , Lee A. Rozema , Chao Zhang , Armin Tavakoli , Philip Walther

The purpose of an entanglement witness experiment is to certify the creation of an entangled state from a finite number of trials. The statistical confidence of such an experiment is typically expressed as the number of observed standard…

Quantum Physics · Physics 2020-04-29 Bas Dirkse , Matteo Pompili , Ronald Hanson , Michael Walter , Stephanie Wehner

Two important ingredients necessary for obtaining Bell nonlocal correlations between two spatially separated parties are an entangled state shared between them and an incompatible set of measurements employed by each of them. We focus on…

Quantum Physics · Physics 2025-05-26 Priya Ghosh , Chirag Srivastava , Swati Choudhary , Ujjwal Sen

We provide a novel criterion for identifying quantum correlation, which allows us to find connections between Bell type inequalities, entanglement detection, and correlation. We utilize the criterion to construct witness operators that can…

Quantum Physics · Physics 2007-05-23 Che-Ming Li , Li-Yi Hsu , Wei-Yang Lin , Yueh-Nan Chen , Der-San Chuu , Tobias Brandes

Detectors in the laboratory are often unlike their ideal theoretical cousins. They have non-ideal efficiencies, which may then lead to non-trivial implications. We show how it is possible to predict correct answers about whether a shared…

Quantum Physics · Physics 2021-06-09 Kornikar Sen , Sreetama Das , Ujjwal Sen

Entanglement is one of the most studied properties of quantum mechanics for its application in quantum information protocols. Nevertheless, detecting the presence of entanglement in large multipartite sates continues to be a great challenge…

Quantum Physics · Physics 2017-06-21 Flavio Baccari , Daniel Cavalcanti , Peter Wittek , Antonio Acín

In Bell scenario, any nonlocal correlation, shared between two spatially separated parties, can be modeled deterministically either by allowing communications between the two parties or by restricting their free will in choosing the…

Quantum Physics · Physics 2013-11-01 Manik Banik

We develop a novel necessary condition of quantum correlation. It is utilized to construct $d$-level bipartite Bell-type inequality which is strongly resistant to noise and requires only analyses of $O(d)$ measurement outcomes compared to…

Quantum Physics · Physics 2007-09-14 Che-Ming Li , Li-Yi Hsu , Yueh-Nan Chen , Der-San Chuu , Tobias Brandes

Given a Bell inequality, if its maximal quantum violation can be achieved only by a single set of measurements for each party or a single quantum state, up to local unitaries, one refers to such a phenomenon as self-testing. For instance,…

Quantum Physics · Physics 2021-09-29 Shin-Liang Chen , Huan-Yu Ku , Wenbin Zhou , Jordi Tura , Yueh-Nan Chen

Bell nonlocality between distant quantum systems---i.e., joint correlations which violate a Bell inequality---can be verified without trusting the measurement devices used, nor those performing the measurements. This leads to…

Quantum Physics · Physics 2015-01-16 Sacha Kocsis , Michael J. W. Hall , Adam J. Bennet , Dylan J. Saunders , G. J. Pryde

Protocols have been previously proposed to certify the presence of an entangled measurement in a fully device-independent manner. Here, I provide models for these protocols in which the claimed measurement is not entangled, and demonstrate…

Quantum Physics · Physics 2026-02-18 Peter Bierhorst