Fluctuating Hydrodynamics of Quantum Fluids from the Nonlinear Fokker-Planck Equation

Abstract

Starting from the nonlinear Fokker-Planck equation (NFPE), we establish the fluctuating hydrodynamics for quantum fluids. We also investigate the corresponding stochastic thermodynamics and derive the associated fluctuation theorems. We then apply this framework to both fermionic and bosonic systems. For the ideal Fermi gas, we study the electrical conduction and reveal a resistance proportional to the product of temperature and the density of states at the Fermi surface. For bosonic fluids, we analyze the relaxation time characterizing the critical slowing down phenomenon and identify three distinct scaling behaviors corresponding to the non-interacting, repulsive interaction, and attractive interaction regimes. Overall, this work provides a experimentally verifiable phenomenological description for the dynamics of quantum fluids and demonstrates the applicability of the nonlinear Fokker-Planck equation in characterizing such systems.