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Entanglement is at the heart of most quantum information tasks, and therefore considerable effort has been made to find methods of deciding the entanglement content of a given bipartite quantum state. Here, we prove a fundamental limitation…

Quantum Physics · Physics 2016-06-15 Claudio Carmeli , Teiko Heinosaari , Antti Karlsson , Jussi Schultz , Alessandro Toigo

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

Although quantum entanglement is an important resource, its characterization is quite challenging. The partial transposition is a common method to detect bipartite entanglement. In this paper, the authors study the…

Quantum Physics · Physics 2024-05-01 Lin Zhang , Ming-Jing Zhao , Lin Chen , Hua Xiang , Yi Shen

We explore the possibility of entanglement detection in continuous variable systems by entanglement witnesses based on covariance matrices, constructible from random homodyne measurements. We propose new linear constraints characterizing…

Quantum Physics · Physics 2021-01-20 Tatiana Mihaescu , Hermann Kampermann , Giulio Gianfelici , Aurelian Isar , Dagmar Bruss

In this paper we address the problem of detection of entanglement using only few local measurements when some knowledge about the state is given. The idea is based on an optimized decomposition of witness operators into local operators. We…

Quantum Physics · Physics 2015-06-26 O. Guehne , P. Hyllus , D. Bruss , A. Ekert , M. Lewenstein , C. Macchiavello , A. Sanpera

We develop a strong and computationally simple entanglement criterion. The criterion is based on an elementary positive map Phi which operates on state spaces with even dimension N >= 4. It is shown that Phi detects many entangled states…

Quantum Physics · Physics 2007-05-23 Heinz-Peter Breuer

We provide a method to construct entanglement criteria for arbitrary multipartite systems of discrete or continuous variables and hybrid combinations of both. While any set of local operators generates a sufficient condition for…

Quantum Physics · Physics 2016-08-09 Manuel Gessner , Luca Pezzè , Augusto Smerzi

Entanglement is a key property of quantum states that acts as a resource for a wide range of tasks in quantum computing. Entanglement detection is a key conceptual and practical challenge. Without adaptive or joint measurements,…

Quantum Physics · Physics 2026-04-07 K. Bharati , Vikesh Siddhu , Krishna Jagannathan

Quantumness and separability criteria for continuous variable systems are discussed for the case of a noncommutative (NC) phase-space. In particular, the quantum nature and the entanglement configuration of NC two-mode Gaussian states are…

Quantum Physics · Physics 2015-10-13 Alex E. Bernardini , Catarina Bastos , Orfeu Bertolami , Nuno C. Dias , João N. Prata

Entanglement is an useful resource because some global operations cannot be locally implemented using classical communication. We prove a number of results about what is and is not locally possible. We focus on orthogonal states, which can…

Quantum Physics · Physics 2009-11-07 Jonathan Walgate , Lucien Hardy

The cosmological constant $\Lambda$ can be achieved as the result of entangled and statistically correlated minisuperspace cosmological states, built up by using a minimal choice of observable quantities, i.e. $\Omega_{m}$ and $\Omega_{k}$,…

General Relativity and Quantum Cosmology · Physics 2015-05-20 S. Capozziello , O. Luongo

Quantum entanglement is a key enabling ingredient in diverse applications. However, the presence of unwanted adversarial entanglement also poses challenges in many applications. In this paper, we explore methods to "break" quantum…

Quantum Physics · Physics 2024-02-26 Fernando G. Jeronimo , Pei Wu

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 in this work a practical approach to address the longstanding and challenging problem of quantum separability, leveraging the correlation matrices of generic observables. General separability conditions are obtained by dint of…

Quantum Physics · Physics 2025-05-07 Ma-Cheng Yang , Cong-Feng Qiao

Necessary and sufficient conditions for bipartite entanglement are derived, which apply to arbitrary Hilbert spaces. Motivated by the concept of witnesses, optimized entanglement inequalities are formulated solely in terms of arbitrary…

Quantum Physics · Physics 2009-11-13 J. Sperling , W. Vogel

To optimize the entanglement detection, we formulate the metrologically operational entanglement condition in quantum Fisher information by maximizing the QFI on the measurement orbit. Specifically, we consider two classes of typical local…

Quantum Physics · Physics 2024-10-28 Ao-Xiang Liu , Ma-Cheng Yang , Cong-Feng Qiao

The high-precision interferometric measurement of an unknown phase is the basis for metrology in many areas of science and technology. Quantum entanglement provides an increase in sensitivity, but present techniques have only surpassed the…

Quantum Physics · Physics 2011-01-25 G. Y. Xiang , B. L. Higgins , D. W. Berry , H. M. Wiseman , G. J. Pryde

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

We develop a novel necessary condition of quantum correlation. It is utilized to construct $d$-level bipartite Bell-type inequality which is strongly resistant to noise and requires only analyses of $O(d)$ measurement outcomes compared to…

Quantum Physics · Physics 2007-09-14 Che-Ming Li , Li-Yi Hsu , Yueh-Nan Chen , Der-San Chuu , Tobias Brandes

We study the problem of distinguishing quantum states using local operations and classical communication (LOCC). A question of fundamental interest is whether there exist sets of $k \leq d$ orthogonal maximally entangled states in…

Quantum Physics · Physics 2014-08-22 Alessandro Cosentino , Vincent Russo