Experimental investigations of stochastic thermodynamics

大约150年前，麦克斯韦第一次问到，当一个“灵巧的手指”被恶魔利用信息从热量中提取功时，会发生什么。热力学第二定律应该禁止这种情况，但如何做到呢？一个多世纪以来，这个问题一直困扰着物理学家，并引发了争论。一年前，在我的实验室里，我们进行了一项决定性的测量，证实了50年前提出的一个假设：麦克斯韦恶魔需要擦除信息，擦除信息需要消耗尽可能多的能量。这里提出的工作将这些想法推广到系统失衡的情况。一个重要的目标是能够测量描述系统不平衡的熵的函数的形式。有人提出，香农熵扮演着这一角色，但从未进行过直接测试。这个函数表面上看起来像19世纪吉布斯-玻尔兹曼关于熵的标准表达式，但它的应用超出了平衡。

Nearly 150 years ago, Maxwell first asked what happens when a “neat fingered being” a demon uses information to extract work from heat. The Second Law of Thermodynamics should forbid this, but how? The question has galled physicists and provoked debate for over a century. One year ago in my laboratory, we made a definitive measurement that confirms a hypothesis proposed 50 years ago: that Maxwell demons need to erase information and that erasing information requires dissipating as much energy as is gained. The work proposed here pursues these ideas to cases where systems are out of equilibrium. One important goal is to be able to measure the form of the function that describes the entropy of a system out of equilibrium. It has been proposed, but never directly tested, that the Shannon entropy plays this role. The function superficially looks like the standard 19th century Gibbs-Boltzmann expression for the entropy but applies out of equilibrium.