Department of Physics, Simon Fraser University, Burnaby, BC, Canada V5A 1S6.
Pacific Institute for the Mathematical Sciences, Unité Mixte Internationale 3069, Vancouver, BC, Canada V6T 1Z4.
Proc Natl Acad Sci U S A. 2017 Oct 17;114(42):11097-11102. doi: 10.1073/pnas.1708689114. Epub 2017 Oct 3.
Stochastic thermodynamics extends classical thermodynamics to small systems in contact with one or more heat baths. It can account for the effects of thermal fluctuations and describe systems far from thermodynamic equilibrium. A basic assumption is that the expression for Shannon entropy is the appropriate description for the entropy of a nonequilibrium system in such a setting. Here we measure experimentally this function in a system that is in local but not global equilibrium. Our system is a micron-scale colloidal particle in water, in a virtual double-well potential created by a feedback trap. We measure the work to erase a fraction of a bit of information and show that it is bounded by the Shannon entropy for a two-state system. Further, by measuring directly the reversibility of slow protocols, we can distinguish unambiguously between protocols that can and cannot reach the expected thermodynamic bounds.
随机热力学将经典热力学扩展到与一个或多个热浴接触的小系统。它可以解释热涨落的影响，并描述远离热力学平衡的系统。一个基本的假设是，香农熵的表达式是在这种情况下描述非平衡系统熵的适当描述。在这里，我们在一个局部但非全局平衡的系统中实验测量了这个函数。我们的系统是一个在水中的微米级胶体粒子，处于由反馈陷阱产生的虚拟双阱势中。我们测量了擦除一部分信息所需的功，并表明它受到两态系统香农熵的限制。此外，通过直接测量慢协议的可逆性，我们可以明确区分能够和不能达到预期热力学限制的协议。
