Niedenzu Wolfgang, Mukherjee Victor, Ghosh Arnab, Kofman Abraham G, Kurizki Gershon
Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
Department of Physics, Shanghai University, Baoshan District, Shanghai, 200444, China.
Nat Commun. 2018 Jan 11;9(1):165. doi: 10.1038/s41467-017-01991-6.
According to the second law, the efficiency of cyclic heat engines is limited by the Carnot bound that is attained by engines that operate between two thermal baths under the reversibility condition whereby the total entropy does not increase. Quantum engines operating between a thermal and a squeezed-thermal bath have been shown to surpass this bound. Yet, their maximum efficiency cannot be determined by the reversibility condition, which may yield an unachievable efficiency bound above unity. Here we identify the fraction of the exchanged energy between a quantum system and a bath that necessarily causes an entropy change and derive an inequality for this change. This inequality reveals an efficiency bound for quantum engines energised by a non-thermal bath. This bound does not imply reversibility, unless the two baths are thermal. It cannot be solely deduced from the laws of thermodynamics.
根据第二定律，循环热机的效率受卡诺界限的限制，该界限由在两个热库之间运行且满足总熵不增加的可逆条件下的热机所达到。已证明在热库和压缩热库之间运行的量子热机能够超越这一界限。然而，它们的最大效率不能由可逆条件确定，因为该条件可能会产生一个高于1的无法实现的效率界限。在这里，我们确定了量子系统与热库之间必然导致熵变化的交换能量的比例，并推导出了这种变化的不等式。该不等式揭示了由非热库驱动的量子热机的效率界限。除非两个热库都是热的，否则这个界限并不意味着可逆性。它不能仅从热力学定律推导得出。
