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We present an intuitive geometrical entanglement criterion. It allows formulation of simple and experimentally friendly sufficient conditions for entanglement. The conditions are illustrated with several examples. Moreover, a generalization…

Quantum Physics · Physics 2015-05-13 P. Badziag , C. Brukner , W. Laskowski , T. Paterek , M. Zukowski

The ability to coherently control mechanical systems with optical fields has made great strides over the past decade, and now includes the use of photon counting techniques to detect the non-classical nature of mechanical states. These…

Quantum Physics · Physics 2018-07-13 Melvyn Ho , Enky Oudot , Jean-Daniel Bancal , Nicolas Sangouard

We present entanglement witness operators for detecting genuine multipartite entanglement. These witnesses are robust against noise and require only two local measurement settings when used in an experiment, independent from the number of…

Quantum Physics · Physics 2007-05-23 Geza Toth , Otfried Guehne

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 construct both nonlinear and linear entanglement witnesses, by tensoring and partial tracing existing states and witnesses. We show that little shared quantum resources allow to employ decomposable witnesses to obtain larger ones…

Quantum Physics · Physics 2025-11-11 Albert Rico

The ultrafine entanglement witness, introduced in [F. Shahandeh, M. Ringbauer, J.C. Loredo, and T.C. Ralph, Phys. Rev. Lett. \textbf{118}, 110502 (2017)], can seamlessly and easily improve any standard entanglement witness. In this paper,…

Quantum Physics · Physics 2018-03-30 Shu-Qian Shen , Ti-Run Xu , Shao-Ming Fei , Xianqing Li-Jost , Ming Li

The primary goal of entanglement theory is to determine convertibility conditions for two quantum states. Up until now, this has always been done with the use of entanglement monotones. With the exception of the negativity, such quantities…

Quantum Physics · Physics 2016-01-14 Mark W. Girard , Gilad Gour

We study the entangled states that can be generated using two species of atoms trapped in independently movable, two-dimensional optical lattices. We show that using two sets of measurements it is possible to measure a set of entanglement…

Quantum Physics · Physics 2010-12-23 Emilio Alba , Geza Toth , Juan Jose Garcia-Ripoll

How can a multipartite single-photon path-entangled state be certified efficiently by means of local measurements? We address this question by constructing an entanglement witness based on local photon detections preceded by displacement…

Genuine multipartite entanglement underlies correlation experiments corroborating quantum mechanics and it is an expedient empowering many quantum technologies. One of many counterintuitive facets of genuine multipartite entanglement is its…

A profound comprehension of quantum entanglement is crucial for the progression of quantum technologies. The degree of entanglement can be assessed by enumerating the entangled degrees of freedom, leading to the determination of a parameter…

Quantum Physics · Physics 2025-04-16 Liang Xiong , Nung-sing Sze

We present a general theory for the construction of witnesses that detect genuine multipartite entanglement in graph states. First, we present explicit witnesses for all graph states of up to six qubits which are better than all criteria so…

Quantum Physics · Physics 2011-10-26 Bastian Jungnitsch , Tobias Moroder , Otfried Gühne

We derive a general framework that connects every positive map with a corresponding witness for partial separability in multipartite quantum systems. We show that many previous approaches were intimately connected to the witnesses derived…

Quantum Physics · Physics 2014-09-10 Marcus Huber , Ritabrata Sengupta

We derive reliable entanglement witnesses for coarse--grained measurements on continuous variable systems. These witnesses never return a "false positive" for identification of entanglement, under any degree of coarse graining. We show…

Quantum Physics · Physics 2013-06-18 D. S. Tasca , Łukasz Rudnicki , R. M. Gomes , F. Toscano , S. P. Walborn

Detecting entanglement in multipartite quantum states is an inherently probabilistic process, typically with a few measured samples. The level of confidence in entanglement detection quantifies the scheme's validity via the probability that…

We present the generalized state-dependent entropic uncertainty relations in multiple measurements setting, and the optimal lower bound is obtained by considering different measurement sequences. We then apply this uncertainty relation to…

Quantum Physics · Physics 2023-06-05 Li-Hang Ren , Yun-Hao Shi , Jin-Jun Chen , Heng Fan

The ability of entangled states to act as resource for teleportation is linked to a property of the fully entangled fraction. We show that the set of states with their fully entangled fraction bounded by a threshold value required for…

Quantum Physics · Physics 2015-05-30 Nirman Ganguly , Satyabrata Adhikari , A. S. Majumdar , Jyotishman Chatterjee

We propose a new measure of non-classicality of quantum gates which is particularly suitable for probabilistic devices. This measure enables to compare, e.g., deterministic devices which prepare entangled states with low amount of…

Quantum Physics · Physics 2013-07-01 Karel Lemr , Antonín Černoch , Jan Soubusta , Miloslav Dušek

We present general numerical methods to construct witness operators for entanglement detection and estimation of the fidelity. Our methods are applied to detecting entanglement in the vicinity of a six-qubit Dicke state with three…

We use matched quantum entanglement witnesses to study the separable criteria of continuous variable states. The witness can be written as an identity operator minus a Gaussian operator. The optimization of the witness then is transformed…

Quantum Physics · Physics 2023-02-22 Xiao-yu Chen , Maoke Miao , Rui Yin , Jiantao Yuan