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Résumé |
In recent years, there has been intense attention on the constraints posed by
quantum
mechanics on the dynamics of the correlation at low temperatures, triggered by the
postulation and derivation of quantum bounds on the transport coefficients or the
chaos
rate. However, the physical meaning and the mechanism enforcing such bounds is
still an
open question.
In this talk, I will discuss the quantum fluctuation-dissipation theorem (the KMS
conditions) in relation to the bounds on correlation time scales.
First of all, I will map out-of-time correlation functions onto ordered two-point
functions in a replicated space. This allows for a simple derivation of the
quantum bound
to chaos as a direct consequence of the KMS condition.
Secondly, I will describe how quantum fluctuation-dissipation relations act in
general as
a blurring of the time-dependence of correlations, which can imply bounds on their
decay
rates.
Thinking in terms of fluctuation-dissipation opens a direct connection between
bounds and
other thermodynamic properties.
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