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The entanglement of a pure state of a pair of quantum systems is defined as the entropy of either member of the pair. The entanglement of formation of a mixed state is defined as the minimum average entanglement of an ensemble of pure…

Quantum Physics · Physics 2009-01-23 William K. Wootters

We show that quantum mechanical entanglement can prevail even in noisy open quantum systems at high temperature and far from thermodynamical equilibrium, despite the deteriorating effect of decoherence. The system consists of a number N of…

Quantum Physics · Physics 2007-05-23 L. Hartmann , W. Dür , H. -J. Briegel

We map the quantum entanglement problem onto the mathematically well-studied truncated moment problem. This yields a necessary and sufficient condition for separability that can be checked by a hierarchy of semi-definite programs. The…

Quantum Physics · Physics 2017-09-20 Fabian Bohnet-Waldraff , Daniel Braun , Olivier Giraud

Long-range quantum correlations between particles are usually formulated by assuming the persistence of an entangled state after the particles have spearated. Here this approach is re-examined based upon studying the correlations present in…

Quantum Physics · Physics 2025-04-03 B. C. Sanctuary

The destruction of quantum interference, decoherence, and the destruction of entanglement both appear to occur under the same circumstances. To address the connection between these two phenomena, we consider the evolution of arbitrary…

Quantum Physics · Physics 2009-11-10 P. J. Dodd , J. J. Halliwell

We consider the separability of various joint states of D-dimensional quantum systems, which we call "qudits." We derive two main results: (i) the separability condition for a two-qudit state that is a mixture of the maximally mixed state…

Quantum Physics · Physics 2012-01-04 P. Rungta , W. J. Munro , K. Nemoto , P. Deuar , G. J. Milburn , C. M. Caves

We study how the entanglement of a maximally entangled pair of particles is affected when one or both of the pair are uniformly accelerated, while the detector remains in an inertial frame. We find that the entanglement is unchanged if all…

Quantum Physics · Physics 2007-09-04 W. L. Ku , M. -C. Chu

We consider properties of states of many qubits, which arise after sending certain entangled states via various noisy channels (white noise, coloured noise, local depolarization, dephasing and amplitude damping). Entanglement of these…

Quantum Physics · Physics 2015-05-13 Wieslaw Laskowski , Tomasz Paterek , Caslav Brukner , Marek Zukowski

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

Hypergraph states are multi-qubit states that form a subset of the locally maximally entangleable states and a generalization of the well--established notion of graph states. Mathematically, they can conveniently be described by a…

Quantum Physics · Physics 2014-08-11 O. Gühne , M. Cuquet , F. E. S. Steinhoff , T. Moroder , M. Rossi , D. Bruß , B. Kraus , C. Macchiavello

In this paper we show an explicit construction of multipartite class of entangled states with the PPT (Positive Partial Transposition) property in every cut. We investigate properties of this class of states focusing on the trace distance…

Quantum Physics · Physics 2019-06-25 Adam Rutkowski , Michał Studziński

We review entangled coherent state research since its first implicit use in 1967 to the present. Entangled coherent states are important to quantum superselection principles, quantum information processing, quantum optics, and mathematical…

Quantum Physics · Physics 2012-06-07 Barry C. Sanders

As separable states are a convex combination of product states, the geometry of the manifold of product states is studied. Prior results by Sanpera, Vidal and Tarrach are extended. Furthermore, it is proven that states in the set tangent to…

Quantum Physics · Physics 2007-05-23 Robert B. Lockhart , Michael J. Steiner , Karl Gerlach

We present a new approach to the analysis of entanglement in smooth bipartite continuous-variable states. One or both parties perform projective filterings via preliminary measurements to determine whether the system is located in some…

Quantum Physics · Physics 2009-11-13 H. -C. Lin , A. J. Fisher

We consider a Quantum Computer with n quantum-bits (`qubits'), where each qubit is coupled independently to an environment affecting the state in a dephasing or depolarizing way. For mixed states we suggest a quantification for the property…

Quantum Physics · Physics 2008-12-18 Dominik Janzing , Thomas Beth

It is known that an interacting bipartite system evolves as an entangled state in general, even if it is initially in a separable state. Due to the entanglement of the state, the geometric phase of the system is not equal to the sum of the…

Quantum Physics · Physics 2015-05-18 C. W. Niu , G. F. Xu , Longjiang Liu , L. Kang , D. M. Tong , L. C. Kwek

In [Science 340, 1205, 7 June (2013)], via polytopes Michael Walter et al. proposed a sufficient condition detecting the genuinely entangled pure states. In this paper, assume that a state with six non-zero coefficients is not a trivially…

Quantum Physics · Physics 2025-10-21 Dafa Li

We study the closest disentangled state to a given entangled state in any system (multi-party with any dimension). We obtain the set of equations the closest disentangled state must satisfy, and show that its reduction is strongly related…

Quantum Physics · Physics 2007-05-23 Satoshi Ishizaka

We find an operational interpretation for the 4-tangle as a type of residual entanglement, somewhat similar to the interpretation of the 3-tangle. Using this remarkable interpretation, we are able to find the class of maximally entangled…

Quantum Physics · Physics 2011-05-10 Gilad Gour , Nolan R. Wallach

Characterizing entanglement of systems composed of multiple particles is a very complex problem that is attracting increasing attention across different disciplines related to quantum physics. The task becomes even more complex when the…

Quantum Physics · Physics 2026-02-12 Shuheng Liu , Qiongyi He , Marcus Huber , Giuseppe Vitagliano