Intravaia F, Behunin R O, Henkel C, Busch K, Dalvit D A R
Max-Born-Institut, 12489 Berlin, Germany.
Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA.
Phys Rev Lett. 2016 Sep 2;117(10):100402. doi: 10.1103/PhysRevLett.117.100402. Epub 2016 Sep 1.
Recent progress in manipulating atomic and condensed matter systems has instigated a surge of interest in nonequilibrium physics, including many-body dynamics of trapped ultracold atoms and ions, near-field radiative heat transfer, and quantum friction. Under most circumstances the complexity of such nonequilibrium systems requires a number of approximations to make theoretical descriptions tractable. In particular, it is often assumed that spatially separated components of a system thermalize with their immediate surroundings, although the global state of the system is out of equilibrium. This powerful assumption reduces the complexity of nonequilibrium systems to the local application of well-founded equilibrium concepts. While this technique appears to be consistent for the description of some phenomena, we show that it fails for quantum friction by underestimating by approximately 80% the magnitude of the drag force. Our results show that the correlations among the components of driven, but steady-state, quantum systems invalidate the assumption of local thermal equilibrium, calling for a critical reexamination of this approach for describing the physics of nonequilibrium systems.
在操控原子和凝聚态物质系统方面的最新进展引发了人们对非平衡态物理的浓厚兴趣，其中包括捕获的超冷原子和离子的多体动力学、近场辐射热传递以及量子摩擦。在大多数情况下，此类非平衡态系统的复杂性需要一些近似方法才能使理论描述易于处理。特别是，人们常常假定系统在空间上分离的各部分会与其紧邻的周围环境达到热平衡，尽管系统的整体状态处于非平衡态。这一有力的假定将非平衡态系统的复杂性简化为对成熟的平衡态概念的局部应用。虽然这种技术对于某些现象的描述似乎是一致的，但我们表明，它在描述量子摩擦时并不适用，因为它将拖曳力的大小低估了约80%。我们的结果表明，受驱动但处于稳态的量子系统各组成部分之间的相关性使局部热平衡的假定无效，这就需要对这种描述非平衡态系统物理的方法进行批判性的重新审视。
