de Assis Rogério J, de Mendonça Taysa M, Villas-Boas Celso J, de Souza Alexandre M, Sarthour Roberto S, Oliveira Ivan S, de Almeida Norton G
Instituto de Física, Universidade Federal de Goiás, 74.001-970, Goiânia-GO, Brazil.
Departamento de Física, Universidade Federal de São Carlos, 13565-905, São Carlos, São Paulo, Brazil.
Phys Rev Lett. 2019 Jun 21;122(24):240602. doi: 10.1103/PhysRevLett.122.240602.
We perform an experiment in which a quantum heat engine works under two reservoirs, one at a positive spin temperature and the other at an effective negative spin temperature, i.e., when the spin system presents population inversion. We show that the efficiency of this engine can be greater than that when both reservoirs are at positive temperatures. We also demonstrate the counterintuitive result that the Otto efficiency can be beaten only when the quantum engine is operating in the finite-time mode.
我们进行了一项实验，其中一个量子热机在两个热库下工作，一个处于正自旋温度，另一个处于有效负自旋温度，即当自旋系统呈现粒子数反转时。我们表明，该热机的效率可以高于两个热库都处于正温度时的效率。我们还证明了一个违反直觉的结果，即只有当量子热机在有限时间模式下运行时，才能超越奥托效率。
