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Entanglement witnesses are one of the most effective methods to detect entanglement. It is known that nonlinear entanglement witnesses provide better entanglement detection than their linear counterparts, in that the former detect a…

Quantum Physics · Physics 2025-12-25 Kornikar Sen , Chirag Srivastava , Ujjwal Sen

Recently, there are tremendous developments on the number of controllable qubits in several quantum computing systems. For these implementations, it is crucial to determine the entanglement structure of the prepared multipartite quantum…

Quantum Physics · Physics 2019-10-10 You Zhou , Qi Zhao , Xiao Yuan , Xiongfeng Ma

Multipartite entanglement is one of the crucial resources in quantum information processing tasks such as quantum metrology, quantum computing and quantum communications. It is essential to verify not only the multipartite entanglement, but…

Quantum Physics · Physics 2024-06-12 Kai Wu , Zhihua Chen , Zhen-Peng Xu , Zhihao Ma , Shao-Ming Fei

Entanglement witnesses form an effective method to locally detect entanglement in the laboratory without having the prior knowledge of the full density matrix. However, separable states can be erroneously indicated as entangled in such…

Quantum Physics · Physics 2021-08-04 Kornikar Sen , Chirag Srivastava , Shiladitya Mal , Aditi Sen De , Ujjwal Sen

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

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

Multipartite entanglement detection is crucial for the develop of quantum information science and quantum computation, communication, simulation and metrology tasks. In contrast to experiments, where several handreds of qubits have been…

Quantum Physics · Physics 2024-11-06 Xiao-yu Chen

Verification of entanglement is an important tool to characterize sources and devices for use in quantum computing and communication applications. In a vast majority of experiments entanglement witnesses (EW) are used in order to prove the…

Quantum Physics · Physics 2012-07-02 Juan Miguel Arrazola , Oleg Gittsovich , Norbert Lütkenhaus

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 propose a scheme for witnessing entanglement in phase space by significantly inefficient detectors. The implementation of this scheme does not require any additional process for correcting errors in contrast to previous proposals.…

Quantum Physics · Physics 2010-01-06 Seung-Woo Lee , Hyunseok Jeong , Dieter Jaksch

Entanglement witnesses (EWs) are a collection of observables that can characterize separable states and, experimentally, estimating EWs can verify entangled states. In this work, we show that a fixed measurement setting on a multipartite…

Quantum Physics · Physics 2026-05-29 Jaemin Kim , Anindita Bera , Dariusz Chruściński , Joonwoo Bae

Entanglement witness is a Hermitian operator that is useful for detecting the genuine multipartite entanglement of mixed states. Nonlinear entanglement witnesses have the advantage of a wider detection range in the entangled region. We…

Quantum Physics · Physics 2020-06-29 K. Aghayar , A. Heshmati , M. A. Jafarizadeh

The controlled generation of entangled states and their subsequent detection are integral aspects of quantum information science. In this work, we analyse the application of nonlinear witnesses to the verification of entanglement, and we…

Quantum Physics · Physics 2012-10-04 Megan Agnew , Jeff Z. Salvail , Jonathan Leach , Robert W. Boyd

Violation of a Bell inequality certifies that the underlying state must be entangled in a device-independent way, although there may exist some entangled states which do not violate such an inequality. On the other hand, for every entangled…

Quantum Physics · Physics 2021-03-17 Chirag Srivastava , Shiladitya Mal , Aditi Sen De , Ujjwal Sen

We propose a method to witness entanglement between two continuous-variable systems in a Gaussian state. Its key ingredient is a local lossy state transfer from the original spatially separated systems onto two spatially separated qubits.…

Quantum Physics · Physics 2021-03-17 Waldemar Klobus , Pawel Cieslinski , Lukas Knips , Pawel Kurzynski , Wieslaw Laskowski

We present a method to certify the entanglement of all bipartite entangled quantum states in a device-independent way. This is achieved by placing the state in a quantum network and constructing a correlation inequality based on an…

Quantum Physics · Physics 2018-12-04 Joseph Bowles , Ivan Šupić , Daniel Cavalcanti , Antonio Acín

In this work, we show a correspondence between linear support vector machines (SVMs) and entanglement witnesses, and use this correspondence to generate entanglement witnesses for bipartite and tripartite qubit (and qudit) target entangled…

Quantum Physics · Physics 2023-03-23 Alexander C. B. Greenwood , Larry T. H. Wu , Eric Y. Zhu , Brian T. Kirby , Li Qian

Ensuring the correct functioning of quantum error correction (QEC) circuits is crucial to achieve fault tolerance in realistic quantum processors subjected to noise. The first checkpoint for a fully operational QEC circuit is to create…

Quantum Physics · Physics 2021-04-14 Andrea Rodriguez-Blanco , Alejandro Bermudez , Markus Müller , Farid Shahandeh

Quantum correlations are at the core of the power of quantum information and are necessary to reach a quantum computational advantage. In the context of continuous-variable quantum systems, another necessary ressource for quantum advantages…

Quantum Physics · Physics 2024-07-26 Carlos E. Lopetegui , Mathieu Isoard , Nicolas Treps , Mattia Walschaers

We discuss an implementation of the entanglement witness, a method to detect entanglement with few local measurements, in systems where entangled electrons are generated both in the spin and orbital degrees of freedom. We address the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Lara Faoro , Fabio Taddei