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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

Genuine multipartite entanglement is arguably the most valuable form of entanglement in the multipartite case, with applications, for instance, in quantum metrology. In order to detect that form of entanglement in multipartite quantum…

Quantum Physics · Physics 2026-04-07 Jakub Szczepaniak , Owidiusz Makuta , Remigiusz Augusiak

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 Stokes and anti-Stokes components of the spectrum of resonance fluorescence of a single trapped atom, which originate from the mechanical coupling between the scattered photons and the quantized motion of the atomic center of mass,…

Quantum Physics · Physics 2009-11-13 David Vitali , Giovanna Morigi , Jürgen Eschner

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…

Although entanglement is a basic resource for reaching quantum advantange in many computation and information protocols, we lack a universal recipe for detecting it, with analytical results obtained for low dimensional systems and few…

Quantum Physics · Physics 2023-11-10 Claudio Sanavio , Edoardo Tignone , Elisa Ercolessi

We use the uncertainty relation between the operators associated to the total number of particles and to the relative phase of two bosonic modes to construct entanglement and Einstein-Podolsky-Rosen steering criteria. These can be tested…

Quantum Physics · Physics 2020-06-12 Matteo Fadel , Laura Ares , Alfredo Luis , Qiongyi He

Entanglement witnesses (EWs) are a fundamental tool for the detection of entanglement. We study the inertias of EWs, i.e., the triplet of the numbers of negative, zero, and positive eigenvalues respectively. We focus on the EWs constructed…

Quantum Physics · Physics 2020-12-02 Yi Shen , Lin Chen , Li-Jun Zhao

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

The efficient witnessing and certification of entanglement is necessitated by its ubiquitous use in various aspects of quantum technologies. In the case of continuous-variable bipartite systems, the Shchukin--Vogel hierarchy gives necessary…

Quantum Physics · Physics 2025-09-09 Elena Callus , Martin Gärttner , Tobias Haas

The generation and the characterization of multipartite entangled light is an important and challenging task in quantum optics. In this paper the entanglement properties of the light emitted from a planar semiconductor microcavity are…

Quantum Physics · Physics 2013-10-11 D. Pagel , H. Fehske , J. Sperling , W. Vogel

In this paper we introduce a criterion for the characterization of Entanglement Witness for multipartite quantum systems. Our approach is based on the characterization of the "tangent space" to the set of pure product states.

Quantum Physics · Physics 2012-10-30 Fabio Masillo

We study the problem of witnessing entanglement among indistinguishable particles. For this purpose, we derive a set of equations which results in necessary and sufficient conditions for probing multipartite entanglement between arbitrary…

Quantum Physics · Physics 2015-04-22 A. Reusch , J. Sperling , W. Vogel

Entanglement witnesses provide tools to detect entanglement in experimental situations without the need of having full tomographic knowledge about the state. If one estimates in an experiment an expectation value smaller than zero, one can…

Quantum Physics · Physics 2013-08-28 Jens Eisert , Fernando G. S. L. Brandao , Koenraad M. R. Audenaert

Unitarity and the optical theorem are used to derive the reduced density matrices of Compton scattering in the presence of a witness particle. Two photons are initially entangled wherein one photon participates in Compton scattering while…

High Energy Physics - Theory · Physics 2023-12-05 Shanmuka Shivashankara

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

We generate and characterise continuous variable polarization entanglement between two optical beams. We first produce quadrature entanglement, and by performing local operations we transform it into a polarization basis. We extend two…

Quantum Physics · Physics 2009-11-10 Warwick P. Bowen , Nicolas Treps , Roman Schnabel , Timothy C. Ralph , Ping Koy Lam

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

This paper presents an efficient method for detecting entanglement in high-dimensional two-qudit states by mapping the Hilbert space onto the space of two qubits. This transformation enables the use of well-established two-qubit…

Quantum Physics · Physics 2026-02-25 Josef Kadlec , Artur Barasiński , Karel Lemr

We present an entanglement criterion for two mode squeezed states which relies on particle counting only. The proposed inequality is optimal for the state under consideration and robust against particle losses up to 2/3. As it does not…

Quantum Physics · Physics 2008-09-16 Christine A. Muschik , Eugene S. Polzik , J. Ignacio Cirac