Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, Changchun, 130012, Jilin, China.
Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), PO Box 644, 48080, Bilbao, Spain.
Sci Rep. 2017 Mar 14;7(1):176. doi: 10.1038/s41598-017-00194-9.
We prove a general theorem that the action of arbitrary classical noise or random unitary channels can not increase the maximum population of any eigenstate of an open quantum system, assuming initial system-environment factorization. Such factorization is the conventional starting point for descriptions of open system dynamics. In particular, our theorem implies that a system can not be ideally cooled down unless it is initially prepared as a pure state. The resultant inequality rigorously constrains the possibility of cooling the system solely through temporal manipulation, i.e., dynamical control over the system Hamiltonian without resorting to measurement based cooling methods. It is a substantial generalization of the no-go theorem claiming that the exact ground state cooling is forbidden given initial system-thermal bath factorization, while here we prove even cooling is impossible under classical noise.
我们证明了一个一般性的定理，即在初始系统-环境因子分解的情况下，任意经典噪声或随机幺正通道的作用都不能增加开放量子系统任何本征态的最大布居数。这种因子分解是开放系统动力学描述的传统起点。特别是，我们的定理意味着，除非系统最初被制备为纯态，否则系统不能被理想地冷却。所得的不等式严格限制了仅通过时间操纵来冷却系统的可能性，即，在不诉诸基于测量的冷却方法的情况下，对系统哈密顿量进行动力学控制。这是一个实质性的推广，即声称在初始系统-热浴因子分解的情况下，精确的基态冷却是被禁止的，而在这里，我们证明即使在经典噪声下，冷却也是不可能的。
