Martínez I A, Roldán É, Dinis L, Petrov D, Parrondo J M R, Rica R A
ICFO-Institut de Ciències Fotòniques, Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain.
Laboratoire de Physique, École Normale Supérieure, CNRS UMR5672 46 Allée d'Italie, 69364 Lyon, France.
Nat Phys. 2016 Jan;12(1):67-70. doi: 10.1038/NPHYS3518.
The Carnot cycle imposes a fundamental upper limit to the efficiency of a macroscopic motor operating between two thermal baths1. However, this bound needs to be reinterpreted at microscopic scales, where molecular bio-motors2 and some artificial micro-engines3-5 operate. As described by stochastic thermodynamics6,7, energy transfers in microscopic systems are random and thermal fluctuations induce transient decreases of entropy, allowing for possible violations of the Carnot limit8. Here we report an experimental realization of a Carnot engine with a single optically trapped Brownian particle as the working substance. We present an exhaustive study of the energetics of the engine and analyse the fluctuations of the finite-time efficiency, showing that the Carnot bound can be surpassed for a small number of non-equilibrium cycles. As its macroscopic counterpart, the energetics of our Carnot device exhibits basic properties that one would expect to observe in any microscopic energy transducer operating with baths at different temperatures9-11. Our results characterize the sources of irreversibility in the engine and the statistical properties of the efficiency-an insight that could inspire new strategies in the design of efficient nano-motors.
卡诺循环为在两个热库之间运行的宏观发动机的效率设定了一个基本的上限。然而，在微观尺度上，这个界限需要重新解释，分子生物发动机和一些人工微发动机在这个尺度上运行。如随机热力学所描述的，微观系统中的能量转移是随机的，热涨落会导致熵的瞬时减少，从而可能违反卡诺极限。在这里，我们报告了一种以单个光阱捕获的布朗粒子为工作物质的卡诺发动机的实验实现。我们对该发动机的能量学进行了详尽的研究，并分析了有限时间效率的涨落，结果表明，在少数非平衡循环中卡诺界限可以被超越。与宏观对应物一样，我们的卡诺装置的能量学表现出一些基本特性，这些特性是人们预期在任何在不同温度的热库下运行的微观能量转换器中观察到的。我们的结果表征了发动机中不可逆性的来源以及效率的统计特性，这一见解可能会激发高效纳米发动机设计的新策略。
