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Neumann Entropy (neumann + entropy)

Distribution by Scientific Domains
Physics and Astronomy100%

Kinds of Neumann Entropy

  • von neumann entropy
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    Selected Abstracts

    Criteria for the entanglement of composite systems with identical particles

    FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 11-12 2004
    G.C. Ghirardi
    We identify a general criterion for detecting entanglement of pure bipartite quantum states describing a system of two identical particles. Such a criterion is based both on the consideration of the Slater-Schmidt number of the fermionic and bosonic analog of the Schmidt decomposition and on the evaluation of the von Neumann entropy of the one-particle reduced statistical operators. [source]

    Symmetry breaking and Wigner molecules in few-electron quantum dots

    PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006
    Constantine Yannouleas
    Abstract We discuss symmetry breaking in two-dimensional quantum dots resulting from strong interelectron repulsion relative to the zero-point kinetic energy associated with the confining potential. Such symmetry breaking leads to the emergence of crystalline arrangements of electrons in the dot. The so-called Wigner molecules form already at field-free conditions. The appearance of rotating Wigner molecules in circular dots under high magnetic field, and their relation to magic angular momenta and quantum-Hall-effect fractional fillings is also discussed. Recent calculations for two electrons in an elliptic quantum dot, using exact diagonalization and an approximate generalized-Heitler,London treatment, show that the electrons can localize and form a molecular dimer for screened interelectron repulsion. The calculated singlet-triplet splitting (J ) as a function of the magnetic field (B ) agrees with cotunneling measurements; its behavior reflects the effective dissociation of the dimer for large B . Knowledge of the dot shape and of J (B ) allows determination of two measures of entanglement (concurrence and von Neumann entropy for indistinguishable fermions), whose behavior correlates also with the dissociation of the dimer. The theoretical value for the concurrence at B = 0 agrees with the experimental estimates. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Entanglement of spin chains with general boundaries and of dissipative systems

    ANNALEN DER PHYSIK, Issue 7-8 2009
    T. Stauber
    Abstract We analyze the entanglement properties of spins (qubits) close to the boundary of spin chains in the vicinity of a quantum critical point and show that the concurrence at the boundary is significantly different from the one of bulk spins. We also discuss the von Neumann entropy of dissipative environments in the vicinity of a (boundary) critical point, such as two Ising-coupled Kondo-impurities or the dissipative two-level system. Our results indicate that the entanglement (concurrence and/or von Neumann entropy) changes abruptly at the point where coherent quantum oscillations cease to exist. The phase transition modifies significantly less the entanglement if no symmetry breaking field is applied and we argue that this might be a general property of the entanglement of dissipative systems. We finally analyze the entanglement of an harmonic chain between the two ends as function of the system size. [source]

    Entanglement of spin chains with general boundaries and of dissipative systems

    ANNALEN DER PHYSIK, Issue 7-8 2009
    T. Stauber
    Abstract We analyze the entanglement properties of spins (qubits) close to the boundary of spin chains in the vicinity of a quantum critical point and show that the concurrence at the boundary is significantly different from the one of bulk spins. We also discuss the von Neumann entropy of dissipative environments in the vicinity of a (boundary) critical point, such as two Ising-coupled Kondo-impurities or the dissipative two-level system. Our results indicate that the entanglement (concurrence and/or von Neumann entropy) changes abruptly at the point where coherent quantum oscillations cease to exist. The phase transition modifies significantly less the entanglement if no symmetry breaking field is applied and we argue that this might be a general property of the entanglement of dissipative systems. We finally analyze the entanglement of an harmonic chain between the two ends as function of the system size. [source]