论文标题
在有限温度下稀释量子流体中有限大小不混杂的随机运动
Stochastic motion of finite-size immiscible impurities in a dilute quantum fluid at finite temperature
论文作者
论文摘要
在有限温度下稀释量子流体中有效的，有限的大小和不混溶的杂质的动力学的特征是投影gross-pitaevskii方程的数值模拟。杂质被建模为局部排斥潜力，并以经典的自由度描述。结果表明，不同尺寸的杂质与流体热效，并在足够大的时间内进行与Ornstein-Uhlenbeck过程兼容的随机动力学。测量速度相关函数和杂质的位移，并观察到随温度的摩擦增加。这种行为是在现象学上解释的，在这种情况下，杂质与热激发的稀释气体交换动量，经历了爱泼斯坦的阻力。
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 projected 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.
