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Subsystem Purity as an Enforcer of Entanglement

S. Bose·I. Fuentes-Guridi·P. L. Knight·V. Vedral
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Abstract

We show that entanglement can always arise in the interaction of an arbitrarily large system in any mixed state with a single qubit in a pure state. This small initial purity is enough to enforce entanglement even when the total entropy is close to maximum. We demonstrate this feature using the Jaynes-Cummings interaction of a two level atom in a pure state with a field in a thermal state at an arbitrarily high temperature. We find the time and temperature variation of a lower bound on the amount of entanglement produced and study the classical correlations quantified by the mutual information.

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S. Bose, I. Fuentes-Guridi, P. L. Knight, V. Vedral. 2002-08-08. Subsystem Purity as an Enforcer of Entanglement. https://doi.org/10.1103/physrevlett.87.050401

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