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arXiv · 1506.05729

Characterization and measurement of qubit-environment entanglement generation during pure dephasing

Katarzyna Roszak·Łukasz Cywiński
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Abstract

We consider the coupling of a qubit in a pure state to an environment in an arbitrary state, and characterize the possibility of qubit-environment entanglement generation during the evolution of the joint system, that leads to pure dephasing of the qubit. We give a simple necessary and sufficient condition on the initial density matrix of the environment together with the properties of the interaction, for appearance of qubit-environment entanglement. Any entanglement created turns out to be detectable by the Peres-Horodecki criterion. Furthermore, we show that for a large family of initial environmental states, the appearance of nonzero entanglement with the environment is necessarily accompanied by a change in the state of the environment (i.e. by the back-action of the qubit).

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Katarzyna Roszak, Łukasz Cywiński. 2015-10-01. Characterization and measurement of qubit-environment entanglement generation during pure dephasing. https://doi.org/10.1103/physreva.92.032310

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