Ryu Sungguen, López Rosa, Serra Llorenç, Sánchez David
Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (CSIC-UIB), E-07122, Palma, Spain.
Nat Commun. 2022 May 6;13(1):2512. doi: 10.1038/s41467-022-30039-7.
Classically, the power generated by an ideal thermal machine cannot be larger than the Carnot limit. This profound result is rooted in the second law of thermodynamics. A hot question is whether this bound is still valid for microengines operating far from equilibrium. Here, we demonstrate that a quantum chiral conductor driven by AC voltage can indeed work with efficiencies much larger than the Carnot bound. The system also extracts work from common temperature baths, violating Kelvin-Planck statement. Nonetheless, with the proper definition, entropy production is always positive and the second law is preserved. The crucial ingredients to obtain efficiencies beyond the Carnot limit are: i) irreversible entropy production by the photoassisted excitation processes due to the AC field and ii) absence of power injection thanks to chirality. Our results are relevant in view of recent developments that use small conductors to test the fundamental limits of thermodynamic engines.
传统上，理想热机产生的功率不能超过卡诺极限。这一深刻结果源于热力学第二定律。一个热门问题是，对于远离平衡运行的微型发动机，这个界限是否仍然有效。在这里，我们证明了由交流电压驱动的量子手性导体确实可以以远高于卡诺界限的效率工作。该系统还能从普通温度浴中提取功，这违反了开尔文 - 普朗克表述。尽管如此，通过适当的定义，熵产生始终为正，第二定律得以保留。获得超越卡诺极限效率的关键因素是：i）由于交流场导致的光辅助激发过程产生的不可逆熵产生；ii）由于手性而不存在功率注入。鉴于最近使用小导体来测试热力发动机基本极限的进展，我们的结果具有相关性。
