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Detection of entanglement in quantum networks consisting of many parties is one of the important steps towards building quantum communication and computation networks. We consider a scenario where the measurement devices used for this…

Quantum Physics · Physics 2017-05-03 Ivan Šupić , Paul Skrzypczyk , Daniel Cavalcanti

We consider the problem of entanglement detection in the presence of faulty, potentially malicious detectors. A common - and, as of yet, the only - approach to this problem is to perform a Bell test in order to identify nonlocality of the…

Quantum Physics · Physics 2024-09-20 Giuseppe Viola , Nikolai Miklin , Mariami Gachechiladze , Marcin Pawłowski

Bell nonlocality describes a manifestation of quantum mechanics that cannot be explained by any local hidden variable model. Its origin lies in the nature of quantum entanglement, although understanding the precise relationship between…

Quantum Physics · Physics 2022-01-03 Kuntal Sengupta , Rana Zibakhsh , Eric Chitambar , Gilad Gour

Entanglement allows for the nonlocality of quantum theory, which is the resource behind device-independent quantum information protocols. However, not all entangled quantum states display nonlocality, and a central question is to determine…

Quantum Physics · Physics 2016-11-09 Daniel Cavalcanti , Leonardo Guerini , Rafael Rabelo , Paul Skrzypczyk

Entanglement, the essential resource in quantum information processing, should be witnessed in many tasks such as quantum computing and quantum communication. The conventional entanglement witness method, relying on an idealized…

Quantum Physics · Physics 2014-04-17 Ping Xu , Xiao Yuan , Luo-Kan Chen , He Lu , Xing-Can Yao , Xiongfeng Ma , Yu-Ao Chen , Jian-Wei Pan

Bell's test, initially devised to distinguish quantum theory from local hidden variable models through {violations of local bounds}, is also a common tool for detecting entanglement. For this purpose, one can assume the quantum description…

Quantum Physics · Physics 2026-04-21 Liang-Liang Sun , Yong-Shun Song , Sixia Yu

Entanglement of quasiclassical (coherent) states of two harmonic oscillators leads to striking quantum effects and is useful for quantum technologies. These effects and applications are closely related to nonlocal correlations inherent in…

Quantum Physics · Physics 2019-05-14 Zhi-Rong Zhong , Jian-Qi Sheng , Li-Hua Lin , Shi-Biao Zheng

Although entanglement is widely recognized as one of the most fascinating characteristics of quantum mechanics, nonlocality remains to be a big labyrinth. The proof of existence of nonlocality is as yet not much convincing because of its…

Quantum Physics · Physics 2007-05-23 Zeng-Bing Chen , Sixia Yu , Yong-De Zhang , Nai-Le Liu

Entanglement detection is essential in quantum information science and quantum many-body physics. It has been proved that entanglement exists almost surely for a random quantum state, while the realizations of effective entanglement…

Quantum Physics · Physics 2022-12-02 Pengyu Liu , Zhenhuan Liu , Shu Chen , Xiongfeng Ma

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

Quantum entanglement plays a crucial role in quantum information processing tasks and quantum mechanics, hence quantifying unknown entanglement is a fundamental task. However, this is also challenging, as entanglement cannot be measured by…

Quantum Physics · Physics 2021-04-27 Xiaodie Lin , Zhenyu Chen , Zhaohui Wei

We consider multipartite quantum state discrimination and show that the minimum-error discrimination by separable measurements is closely related to the concept of entanglement witness. Based on the properties of entanglement witness, we…

Quantum Physics · Physics 2023-04-25 Donghoon Ha , Jeong San Kim

Characterizing entanglement is central for quantum information science. Special observables which indicate entanglement, so-called entanglement witnesses, are a widely used tool for this task. The construction of these witnesses typically…

Quantum Physics · Physics 2024-09-30 Chengjie Zhang , Sophia Denker , Ali Asadian , Otfried Gühne

It is well known that the effect of quantum nonlocality, as witnessed by violation of a Bell inequality, can be observed even when relaxing the assumption of measurement independence, i.e. allowing for the source to be partially correlated…

Quantum Physics · Physics 2023-11-17 Ivan Šupić , Jean-Daniel Bancal , Nicolas Brunner

We propose two semi-device-independent approaches that are able to quantify unknown multipartite quantum entanglement experimentally, where the only information that has to be known beforehand is quantum dimension, and the concept that…

Quantum Physics · Physics 2022-01-05 Lijinzhi Lin , Zhaohui Wei

We propose an innovative method to enhance the detection and protection of quantum entanglement, a cornerstone of quantum mechanics with applications in computing, communication, and beyond. While entanglement can be represented through…

Quantum Physics · Physics 2024-12-17 Haruki Matsunaga , Le Bin Ho

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

The quantification of the entanglement present in a physical system is of para\-mount importance for fundamental research and many cutting-edge applications. Currently, achieving this goal requires either a priori knowledge on the system or…

Bell nonlocality refers to correlations between two distant, entangled particles that challenge classical notions of local causality. Beyond its foundational significance, nonlocality is crucial for device-independent technologies like…

The ability to witness non-local correlations lies at the core of foundational aspects of quantum mechanics and its application in the processing of information. Commonly, this is achieved via the violation of Bell inequalities.…

Quantum Physics · Physics 2019-05-23 Askery Canabarro , Samuraí Brito , Rafael Chaves