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We give a review on entanglement purification for bipartite and multipartite quantum states, with the main focus on theoretical work carried out by our group in the last couple of years. We discuss entanglement purification in the context…

Quantum Physics · Physics 2009-11-13 W. Dür , H. J. Briegel

We review some counterintuitive properties of standard measures describing quantum entanglement and violation of Bell's inequality (often referred to as "nonlocality") in two-qubit systems. By comparing the nonlocality, negativity,…

Quantum Physics · Physics 2020-01-10 Adam Miranowicz , Bohdan Horst , Andrzej Koper

We introduce a generalization of entanglement based on the idea that entanglement is relative to a distinguished subspace of observables rather than a distinguished subsystem decomposition. A pure quantum state is entangled relative to such…

Quantum Physics · Physics 2009-11-10 Howard Barnum , Emanuel Knill , Gerardo Ortiz , Rolando Somma , Lorenza Viola

We introduce a hierarchy of linear systems for showing that a given subspace of pure quantum states is entangled (i.e., contains no product states). This hierarchy outperforms known methods already at the first level, and it is complete in…

Quantum Physics · Physics 2023-01-02 Nathaniel Johnston , Benjamin Lovitz , Aravindan Vijayaraghavan

These two accompanying papers treat two mode entanglement for systems of identical massive bosons and the relationship to spin squeezing and other quantum correlation effects. Entanglement is a key quantum feature of composite systems where…

Quantum Physics · Physics 2016-06-01 Bryan Dalton , John Goold , Barry Garraway , Margaret Reid

Pure multipartite quantum states of n parties and local dimension q are called k-uniform if all reductions to k parties are maximally mixed. These states are relevant for our understanding of multipartite entanglement, quantum information…

Quantum Physics · Physics 2020-12-24 Zahra Raissi , Adam Teixido , Christian Gogolin , Antonio Acin

A new class of folded subspace codes for noncoherent network coding is presented. The codes can correct insertions and deletions beyond the unique decoding radius for any code rate $R\in[0,1]$. An efficient interpolation-based decoding…

Information Theory · Computer Science 2015-04-22 Hannes Bartz , Vladimir Sidorenko

We provide a classification of entangled states that uses new discrete entanglement invariants. The invariants are defined by algebraic properties of linear maps associated with the states. We prove a theorem on a correspondence between the…

Quantum Physics · Physics 2013-01-08 Roman V. Buniy , Thomas W. Kephart

We derive an analytical expression for the lower bound of the concurrence of mixed quantum states of composite 2xK systems. In contrast to other, implicitly defined entanglement measures, the numerical evaluation of our bound is…

Quantum Physics · Physics 2009-11-10 Artur Lozinski , Andreas Buchleitner , Karol Zyczkowski , Thomas Wellens

Entanglement is a striking feature of quantum mechanics, and it has a key property called unextendibility. In this paper, we present a framework for quantifying and investigating the unextendibility of general bipartite quantum states.…

Quantum Physics · Physics 2024-03-28 Kun Wang , Xin Wang , Mark M. Wilde

Characterizing entanglement in all but the simplest case of a two qubit pure state is a hard problem, even understanding the relevant experimental quantities that are related to entanglement is difficult. It may not be necessary, however,…

Quantum Physics · Physics 2015-06-26 J. Grondalski , D. M. Etlinger , D. F. V. James

``Leakage'' errors are particularly serious errors which couple states within a code subspace to states outside of that subspace thus destroying the error protection benefit afforded by an encoded state. We generalize an earlier method for…

Quantum Physics · Physics 2009-11-10 Mark S. Byrd , Daniel A. Lidar , Lian-Ao Wu , Paolo Zanardi

The computation of quantum entanglement can be formulated as a high-dimensional nonconvex optimization problem with orthogonality constraints. In this work, we propose structure-preserving consensus-based optimization (CBO) methods for…

Quantum Physics · Physics 2026-05-12 Michael Herty , Yijia Tang , Yizhou Zhou

Entangled qubit can increase the capacity of quantum error correcting codes based on stabilizer codes. In addition, by using entanglement quantum stabilizer codes can be construct from classical linear codes that do not satisfy the…

Quantum Physics · Physics 2015-05-30 Jeonghwan Shin , Jun Heo , Todd A. Brun

Quantum error correction allows for faulty quantum systems to behave in an effectively error free manner. One important class of techniques for quantum error correction is the class of quantum subsystem codes, which are relevant both to…

Quantum Physics · Physics 2013-05-29 Gregory M. Crosswhite , Dave Bacon

The dual of an entanglement-assisted quantum error-correcting (EAQEC) code is defined from the orthogonal group of a simplified stabilizer group. From the Poisson summation formula, this duality leads to the MacWilliams identities and…

Quantum Physics · Physics 2013-05-17 Ching-Yi Lai , Todd A. Brun , Mark M. Wilde

We provide a general description of the phenomenon of entanglement in bipartite systems, as it manifests in micro and macro physical systems, as well as in human cognitive processes. We do so by observing that when genuine coincidence…

An important problem in quantum information theory is the quantification of entanglement in multipartite mixed quantum states. In this work, a connection between the geometric measure of entanglement and a distance measure of entanglement…

Quantum Physics · Physics 2010-12-08 Alexander Streltsov , Hermann Kampermann , Dagmar Bruß

Among the many facets of quantum correlations, bound entanglement has remained one the most enigmatic phenomena, despite the fact that it was discovered in the early days of quantum information. Even its detection has proven to be…

Quantum Physics · Physics 2016-09-07 Gael Sentís , Christopher Eltschka , Jens Siewert

The problem of detecting non-classical correlations of states of many qudits is incomparably more involved than in a case of qubits. The reason is that for qubits we have a convenient description of the system by the means of the…

Quantum Physics · Physics 2016-10-27 Krzysztof Rosołek , Marcin Wieśniak , Lukas Knips