42,930 research outputs found
Bright and Dark periods in the Entanglement Dynamics of Interacting Qubits in Contact with the Environment
Interaction among the qubits are basis to many quantum logic operations. We
report how such inter-qubit interactions can lead to new features, in the form
of bright and dark periods in the entanglement dynamics of two qubits subject
to environmental perturbations. These features are seen to be precursors to the
well known phenomenon of sudden death of entanglement [Yu & Eberly, Phys.
Rev. Lett. {\bf 93}, 140404 (2004)] for noninteracting qubits. Further we find
that the generation of bright and dark periods are generic and occur for wide
varieties of the models of environment. We present explicit results for two
popular models.Comment: New published version, corrected figure
Photon-Photon Correlations as a Probe of Vacuum Induced Coherence Effects
We present new experimental implications of the effects of vacuum induced
coherence on the photon -photon correlation in the pi-polarized fluorescence in
j = 1/2 to j = 1/2 transition. These effects should be thus observable in
measurements of photon statistics in for example Hg and Ba ion traps.Comment: 7 pages, 6 figures, submitted to Physical Review
Nonclassical Correlation of Polarization Entangled Photons in a Biexciton-Exciton Cascade
We develop a theoretical model to study the Intensity-Intensity correlation
of polarization entangled photons emitted in a biexciton-exciton cascade. We
calculate the degree of correlation and show how polarization correlation are
affected by the presence of dephasing and energy level splitting of the
excitonic states. Our theoretical calculations are in agreement with the recent
observation of polarization dependent Intensity-Intensity correlations from a
single semiconductor quantum dot [R. M. Stevenson et. al., Nature 439, 179
(2006)] . Our model can be extended to study polarization entangled photon
emission in coupled quantum dot systems
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