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Based on correlations of coherently displaced photon-numbers, we derive entanglement criteria for the purpose to verify non-Gaussian entanglement. Our construction method enables us to verify bipartite and multipartite entanglement of…

Quantum Physics · Physics 2017-09-08 B. Kühn , W. Vogel , J. Sperling

To address the outstanding task of detecting entanglement in large quantum systems, entanglement witnesses have emerged, addressing the separable nature of a state. Yet optimizing witnesses, or accessing them experimentally, often remains a…

We frame entanglement detection as a problem of random variable inference to introduce a quantitative method to measure and understand whether entanglement witnesses lead to an efficient procedure for that task. Hence we quantify how many…

Quantum Physics · Physics 2023-08-16 Paulo J. Cavalcanti , Giovanni Scala , Antonio Mandarino , Cosmo Lupo

We present an unifying approach to the quantification of entanglement based on entanglement witnesses, which includes several already established entanglement measures such as the negativity, the concurrence and the robustness of…

Quantum Physics · Physics 2007-05-23 Fernando Guadalupe Santos Lins Brandao

We present a class of entanglement identifiers which has the following experimentally friendly feature: once the expectation value of the identifier exceeds some definite limit, we can conclude the state is entangled, even if not all…

Quantum Physics · Physics 2013-08-22 Wieslaw Laskowski , Marcin Markiewicz , Tomasz Paterek , Ryszard Weinar

Entanglement witnesses (EW) allow the detection of entanglement in a quantum system, from the measurement of some few observables. They do not require the complete determination of the quantum state, which is regarded as a main advantage.…

Quantum Physics · Physics 2012-02-02 J. G. Filgueiras , T. O. Maciel , R. E. Auccaise , R. O. Vianna , R. S. Sarthour , I. S. Oliveira

An entanglement witness is an observable with the property that a negative expectation value signals the presence of entanglement. The question arises how a witness can be improved if the expectation value of a second observable is known,…

Quantum Physics · Physics 2018-08-03 Mariami Gachechiladze , Nikolai Wyderka , Otfried Gühne

In quantum information theory, the reliable and effective detection of entanglement is of paramount importance. However, given an unknown state, assessing its entanglement is a challenging task. To attack this problem, we investigate the…

Quantum Physics · Physics 2015-12-09 Jochen Szangolies , Hermann Kampermann , Dagmar Bruß

We address the problem of optimising entanglement witnesses when a limited fixed set of local measurements can be performed on a bipartite system, thus providing a procedure, feasible also for experiments, to detect entangled states using…

Quantum Physics · Physics 2020-07-01 Alberto Riccardi , Dariusz Chruściński , Chiara Macchiavello

There always exists an entanglement witness for every entangled quantum state. Negativity of the expectation value of an entanglement witness operator guarantees entanglement of the corresponding state, given that the measurement devices…

Quantum Physics · Physics 2021-03-24 Kornikar Sen , Chirag Srivastava , Shiladitya Mal , Aditi Sen De , Ujjwal Sen

Entanglement detection problem is one of the important problem in quantum information theory. Gurvit showed that this problem is NP complete and thus this may be the possible reason that only one criterion is not sufficient to detect all…

Quantum Physics · Physics 2023-01-25 Shruti Aggarwal , Satyabrata Adhikari

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

Detection of entanglement is an indispensable step to practical quantum computation and communication. Compared with the conventional entanglement witness method based on fidelity, we propose a flexible, machine learning assisted…

Quantum Physics · Physics 2022-11-11 Jue Xu , Qi Zhao

We introduce a new kind of Entanglement Witness which is appropriate for studying genuine multipartite entanglement in large systems. The witness operator has a form that fits naturally to quantum states represented by tensor networks. It…

Quantum Physics · Physics 2019-11-13 Lucas B. Vieira , Diego L. Braga Ferreira , Thiago O. Maciel , Reinaldo O. Vianna

Optomechanical systems open new possibilities in fundamental research at the interface between quantum information and gravity. Recently, an ambitious experimental proposal was suggested by Bose et al. to measure the entanglement between…

Quantum Physics · Physics 2022-03-03 Thomas Guff , Nicolas Boulle , Igor Pikovski

We introduce a feasible method of constructing the entanglement witness that detects the genuine entanglement of a given pure multiqubit state. We illustrate our method in the scenario of constructing the witnesses for the multiqubit states…

Quantum Physics · Physics 2009-11-13 Lin Chen , Yi-Xin Chen

Having common reference frames or aligned coordinate systems, is one of the presumptions in witnessing entanglement in a two-party state possessed by two remote parties. This assumption may fail for many reasons. With an unlimited supply of…

Quantum Physics · Physics 2024-05-31 Vahid Jannessary , Fatemeh Rezazadeh , Sadegh Raeisi , Vahid Karimipour

We extend the definition of entanglement witnesses based on structure factors to the case in which the position of the scatterers is quantized. This allows us to study entanglement detection in hybrid systems. We provide several examples…

Quantum Physics · Physics 2015-06-19 Massimo Borrelli , Matteo Rossi , Chiara Macchiavello , Sabrina Maniscalco

Multipartite entanglement is the key resource allowing quantum devices to outperform their classical counterparts, and entanglement certification is fundamental to assess any quantum advantage. The only scalable certification scheme relies…

Quantum Physics · Physics 2021-07-28 Irénée Frérot , Tommaso Roscilde

Entanglement plays a crucial role in quantum information science and many-body physics, yet quantifying it in mixed quantum many-body systems has remained a notoriously difficult problem. Here, we introduce families of quantitative…

Quantum Physics · Physics 2025-07-21 Poetri Sonya Tarabunga , Tobias Haug