Stochastic motion of finite-size immiscible impurities in a dilute quantum fluid at finite temperature

Article

关键词: BOSE-EINSTEIN CONDENSATION;    LIQUID-HELIUM;    DISSIPATION;    MODEL;    FLOW;   

DOI  :  10.1103/PhysRevB.103.024509

来源: SCIE

【 摘 要 】

The dynamics of an active, finite-size, and immiscible impurity in a dilute quantum fluid at finite temperature is characterized by means of numerical simulations of the Fourier truncated Gross-Pitaevskii equation. The impurity is modeled as a localized repulsive potential and described with classical degrees of freedom. It is shown that impurities of different sizes thermalize with the fluid and undergo a stochastic dynamics compatible with an Ornstein-Uhlenbeck process at sufficiently large time lags. The velocity correlation function and the displacement of the impurity are measured and an increment of the friction with temperature is observed. Such behavior is phenomenologically explained in a scenario where the impurity exchanges momentum with a dilute gas of thermal excitations, experiencing an Epstein drag.

【 授权许可】

Free