6,726 research outputs found
Entropy exchange, coherent information and concurrence
For a simple model we derive analytic expressions of entropy exchange and
coherent information, from which relations between them and the concurrence are
drawn. We find that in the quantum evolution the entropy exchange exhibits
behavior \textsl{opposite} to that of the concurrence, whereas the coherent
information shows features very similar to those of the concurrence. The
meaning of this result for general systems is discussed.Comment: 4 pages, 8 figures v2: version accepted for publication in Phys. Rev.
Comment on ``Geometric phase of entangled spin pairs in a magnetic field''
The degree of entanglement between two spins may change due to interaction.
About this we find that a wrong result in a recent work by Ge and Wadati [Phys.
Rev. A {\bf72}, 052101(2005)] which breach the basic principle.Comment: 2 pages, comment on Phys. Rev. A {\bf72}, 052101(2005), and to appear
in Phys. Rev.
Stable knots in the trapped Bose-Einstein condensates
The knot of spin texture is studied within the two-component Bose-Einstein
condensates which are described by the nonlinear Gross-Pitaevskii equations. We
start from the non-interacting equations including an axisymmetric harmonic
trap to obtain an exact solution, which exhibits a non-trivial topological
structure. The spin-texture is a knot with an integral Hopf invariant. The
stability of the knot is verified by numerically evolving the nonlinear
Gross-Pitaevskii equations along imaginary time.Comment: 4 pages, 5 figure
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