Planckian dissipation from classical hydrodynamics (opens in new tab)

In this work we ask what the self-consistency of a classical hydrodynamic description imposes on a quantum system. The quantum fluctuation-dissipation theorem, when read in the time domain, acts as a blurring of the fine details of the correlation functions on a Plankian time-scale. We track this blurring along rays inside the light cone for three phenomenological hydrodynamic equations -- diffusion, telegraph and diffusive-telegraph -- and find...