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We qualify the entanglement of arbitrary mixed states of bipartite quantum systems by comparing global and marginal mixednesses quantified by different entropic measures. For systems of two qubits we discriminate the class of maximally…

Quantum Physics · Physics 2007-05-23 Gerardo Adesso , Fabrizio Illuminati , Silvio De Siena

Localizability of entanglement in fully inseparable states is a key ingredient of assisted quantum information protocols as well as measurement-based models of quantum computing. We investigate the existence of fully inseparable states with…

Quantum Physics · Physics 2017-10-31 M. Mičuda , D. Koutný , M. Miková , I. Straka , M. Ježek , L. Mišta

Preparing and certifying bound entangled states in the laboratory is an intrinsically hard task, due to both the fact that they typically form narrow regions in the state space, and that a certificate requires a tomographic reconstruction…

Quantum Physics · Physics 2018-12-20 Gael Sentís , Johannes N. Greiner , Jiangwei Shang , Jens Siewert , Matthias Kleinmann

Based on the residual entanglement [9] (Phys. Rev. A \textbf{71}, 044301 (2005)), we present the global entanglement for a multipartite quantum state. The measure is shown to be also obtained by the bipartite partitions of the multipartite…

Quantum Physics · Physics 2009-11-13 Chang-shui Yu , He-shan Song

The distribution of entanglement between macroscopically separated parties represents a crucial protocol for future quantum information networks. Surprisingly, it has been theoretically shown that two distant systems can be entangled by…

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

Non-locality without entanglement is a rather counter-intuitive phenomenon in which information may be encoded entirely in product (unentangled) states of composite quantum systems in such a way that local measurement of the subsystems is…

Quantum Physics · Physics 2017-03-08 Sarah Croke , Stephen M Barnett

For a given Hamiltonian $H$ on a multipartite quantum system, one is interested in finding the energy $E_0$ of its ground state. In the separability approximation, arising as a natural consequence of measurement in a separable basis, one…

Motivated to understand how entanglement resources can be distributed in quantum networks, we introduce threshold entanglement (TE) states. These are multipartite quantum states whose entanglement across bipartitions forces all marginals of…

The apparent difficulty in recovering classical nonlinear dynamics and chaos from standard quantum mechanics has been the subject of a great deal of interest over the last twenty years. For open quantum systems - those coupled to a…

Quantum Physics · Physics 2007-05-23 M. J. Everitt , T. D. Clark , P. B. Stiffell , J. F. Ralph , A. R. Bulsara , C. J. Harland

A central question since the beginning of quantum information science is how two distant parties can convert one entangled state into another. It has been conjectured that such conversions could be executed reversibly in an asymptotic…

Quantum Physics · Physics 2025-07-08 Ray Ganardi , Tulja Varun Kondra , Nelly H. Y. Ng , Alexander Streltsov

Bound entanglement, being entangled yet not distillable, is essential to our understandings of the relations between nonlocality and entanglement besides its applications in certain quantum information tasks. Recently, bound entangled…

Quantum Physics · Physics 2017-03-22 Sixia Yu , C. H. Oh

We study experimentally accessible lower bounds on entanglement measures based on entropic uncertainty relations. Experimentally quantifying entanglement is highly desired for applications of quantum simulation experiments to fundamental…

Quantum Physics · Physics 2021-05-25 Bjarne Bergh , Martin Gärttner

Quantum steering, loosely speaking the distribution of entanglement from an untrusted party, is a form of quantum nonlocality which is intermediate between entanglement and Bell nonlocality. Determining which states can be steered is…

Quantum Physics · Physics 2013-03-06 Nicolas Brunner , Daniel Cavalcanti

This thesis is an attempt to enhance understanding of the following questions A- Given a multipartite quantum state (possibly mixed), how to find out whether it is entangled or separable? (Detection of entanglement.) B- Given an entangled…

Quantum Physics · Physics 2009-05-05 Ali Saif M. Hassan

Separability problem, to decide whether a given state is entangled or not, is a fundamental problem in quantum information theory. We propose a powerful and computationally simple separability criterion, which allows us to detect the…

Quantum Physics · Physics 2009-11-13 Cheng-Jie Zhang , Yong-Sheng Zhang , Shun Zhang , Guang-Can Guo

Entanglement has evolved from an enigmatic concept of quantum physics to a key ingredient of quantum technology. It explains correlations between measurement outcomes that contradict classical physics, and has been widely explored with…

Quantum Physics · Physics 2024-06-05 Philip Thomas , Leonardo Ruscio , Olivier Morin , Gerhard Rempe

Quantum entanglement is a key physical resource in quantum information processing that allows for performing basic quantum tasks such as teleportation and quantum key distribution, which are impossible in the classical world. Ever since the…

Quantum Physics · Physics 2020-07-29 Xin Wang , Mark M. Wilde

Quantum entanglement is usually revealed via a well aligned, carefully chosen set of measurements. Yet, under a number of experimental conditions, for example in communication within multiparty quantum networks, noise along the channels or…

The notion of entanglement of quantum states is usually defined with respect to a fixed bipartition. Indeed, a global basis change can always map an entangled state to a separable one. The situation is however different when considering a…

Quantum Physics · Physics 2021-06-02 Yu Cai , Baichu Yu , Pooja Jayachandran , Nicolas Brunner , Valerio Scarani , Jean-Daniel Bancal