Spiechowicz J, Łuczka J
Institute of Physics, University of Silesia, 41-500, Chorzów, Poland.
Sci Rep. 2021 Feb 18;11(1):4088. doi: 10.1038/s41598-021-83617-y.
Experimentalists have come to temperatures very close to absolute zero at which physics that was once ordinary becomes extraordinary. In such a regime quantum effects and fluctuations start to play a dominant role. In this context we study the simplest open quantum system, namely, a free quantum Brownian particle coupled to thermal vacuum, i.e. thermostat in the limiting case of absolute zero temperature. We analyze the average energy [Formula: see text] of the particle from a weak to strong interaction strength c between the particle and thermal vacuum. The impact of various dissipation mechanisms is considered. In the weak coupling regime the energy tends to zero as [Formula: see text] while in the strong coupling regime it diverges to infinity as [Formula: see text]. We demonstrate it for selected examples of the dissipation mechanisms defined by the memory kernel [Formula: see text] of the Generalized Langevin Equation. We reveal how at a fixed value of c the energy E(c) depends on the dissipation model: one has to compare values of the derivative [Formula: see text] of the dissipation function [Formula: see text] at time [Formula: see text] or at the memory time [Formula: see text] which characterizes the degree of non-Markovianity of the Brownian particle dynamics. The impact of low temperature is also presented.
实验人员已经达到了非常接近绝对零度的温度，在这个温度下，曾经普通的物理现象变得非同寻常。在这样的状态下，量子效应和涨落开始起主导作用。在此背景下，我们研究最简单的开放量子系统，即一个与热真空耦合的自由量子布朗粒子，也就是在绝对零度极限情况下的恒温器。我们分析了粒子与热真空之间从弱到强的相互作用强度c下粒子的平均能量[公式：见原文]。考虑了各种耗散机制的影响。在弱耦合 regime 中，能量随着[公式：见原文]趋于零，而在强耦合 regime 中，它随着[公式：见原文]发散到无穷大。我们通过广义朗之万方程的记忆核[公式：见原文]定义的耗散机制的选定示例来证明这一点。我们揭示了在固定的c值下，能量E(c)如何依赖于耗散模型：必须比较耗散函数[公式：见原文]在时间[公式：见原文]或记忆时间[公式：见原文]处的导数[公式：见原文]的值，该值表征了布朗粒子动力学非马尔可夫性的程度。还展示了低温的影响。
