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arXiv · 1909.05025

Quadrature coherence scale driven fast decoherence of bosonic quantum field states

Anaelle Hertz·Stephan De Bièvre
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Abstract

We introduce, for each state of a bosonic quantum field, its quadrature coherence scale (QCS), a measure of the range of its quadrature coherences. Under coupling to a thermal bath, the purity and QCS are shown to decrease on a time scale inversely proportional to the QCS squared. The states most fragile to decoherence are therefore those with quadrature coherences far from the diagonal. We further show a large QCS is difficult to measure since it induces small scale variations in the state's Wigner function. These two observations imply a large QCS constitutes a mark of "macroscopic coherence". Finally, we link the QCS to optical classicality: optical classical states have a small QCS and a large QCS implies strong optical nonclassicality.

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Anaelle Hertz, Stephan De Bièvre. 2020-03-11. Quadrature coherence scale driven fast decoherence of bosonic quantum field states. https://doi.org/10.1103/physrevlett.124.090402

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