25 May 2005 Decoherence and loss of entanglement
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We review our recent work establishing by an explicit many-body calculation for an open quantum-mechanical system of two qubits subject to independent noise modelled by bosonic baths, a newly identified connection between two important quantities in the studies of entanglement and decoherence. We demonstrate that the decay of entanglement is governed by the product of the suppression factors describing decoherence of the subsystems (qubits). This result is a detailed model calculation proving an important and intuitively natural physical property that separated open quantum systems can evolve coherently, quantum mechanically on time scales larger than the times for which they remain entangled. Our result also suggests avenues for future work. Specifically, for multiqubit systems, it is expected that similar arguments should apply "by induction." This will stimulate research to develop appropriate quantitative measures of entanglement, and attempts to quantify entanglement and decoherence in a unified way. We considered one "physically meaningful" measure of two-qubit entanglement, the concurrence. In future research, it would be of interest to obtain similar results for other measures of entanglement as well.
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Vladimir Privman, Denis Tolkunov, "Decoherence and loss of entanglement", Proc. SPIE 5815, Quantum Information and Computation III, (25 May 2005); doi: 10.1117/12.604078; https://doi.org/10.1117/12.604078

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