70 research outputs found
Entanglement dynamics and decoherence of an atom coupled to a dissipative cavity field
In this paper, we investigate the entanglement dynamics and decoherence in
the interacting system of a strongly driven two-level atom and a single mode
vacuum field in the presence of dissipation for the cavity field. Starting with
an initial product state with the atom in a general pure state and the field in
a vacuum state, we show that the final density matrix is supported on space, and therefore, the concurrence can be used as
a measure of entanglement between the atom and the field. The influences of the
cavity decay on the quantum entanglement of the system are also discussed. We
also examine the Bell-CHSH violation between the atom and the field and show
that there are entangled states for which the Bell-BCSH inequality is not
violated. Using the above system as a quantum channel, we also investigate the
quantum teleportation of a generic qubit state and also a two-qubit entangled
state, and show that in both cases the atom-field entangled state can be useful
to teleport an unknown state with fidelity better than any classical channel.Comment: 17 pages, 6 figure
Robustness of Entanglement for Bell Decomposable States
We propose a simple geometrical approach for finding the robustness of
entanglement for Bell decomposable states of 2 otimes 2 quantum systems. It is
shown that the robustness of entanglement is equal to the concurrence. We also
present an analytical expression for two separable states that wipe out all
entanglement of these states. Finally the random robustness of these states is
also obtained.Comment: 11 pages, Late
The effect of spin-orbit interaction on entanglement of two-qubit Heisenberg XYZ systems in an inhomogeneous magnetic field
The role of spin-orbit interaction on the ground state and thermal
entanglement of a Heisenberg XYZ two-qubit system in the presence of an
inhomogeneous magnetic field is investigated. For a certain value of spin-orbit
parameter , the ground state entanglement tends to vanish suddenly and when
crosses its critical value , the entanglement undergoes a revival. The
maximum value of the entanglement occurs in the revival region. In finite
temperatures there are revival regions in plane. In these regions,
entanglement first increases with increasing temperature and then decreases and
ultimately vanishes for temperatures above a critical value. This critical
temperature is an increasing function of , thus the nonzero entanglement can
exist for larger temperatures. In addition, the amount of entanglement in the
revival region depends on the spin-orbit parameter. Also, the entanglement
teleportation via the quantum channel constructed by the above system is
investigated and finally the influence of the spin-orbit interaction on the
fidelity of teleportation and entanglement of replica state is studied.Comment: Two columns, 9 pages, 8 Fig
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