标题： 量子态的温度的操作性定义 显示英文标题

标题： Operational definition of the temperature of a quantum state

摘要： 温度通常定义为处于热平衡的物理系统的属性。 然而人们可能会想知道，是否可能将一个有意义的温度概念赋予任意量子态，而不仅仅是热（Gibbs）态。 在本工作中，我们提出了一种温度的概念，考虑了一个操作任务，该任务受到热力学第零定律的启发。 具体而言，我们定义了两种有效温度，以量化量子系统冷却或加热热环境的能力。 通过这种方式，我们可以将一个操作上有意义的温度概念与任何量子密度矩阵相关联。 我们提供了这些有效温度的一般表达式，适用于单拷贝和多拷贝系统，并建立了与文献中先前讨论的概念之间的联系。 最后，我们考虑了一个更复杂的场景，其中系统与热环境之间的热量交换由量子参考系协助。 这导致了一种“相干量子催化”效应，其中使用相干催化剂允许利用系统中的量子能量相干性，现在导致更冷或更热的有效温度。 显示英文摘要

摘要： Temperature is usually defined for physical systems at thermal equilibrium. Nevertheless one may wonder if it would be possible to attribute a meaningful notion of temperature to an arbitrary quantum state, beyond simply the thermal (Gibbs) state. In this work, we propose such a notion of temperature considering an operational task, inspired by the Zeroth Law of thermodynamics. Specifically, we define two effective temperatures for quantifying the ability of a quantum system to cool down or heat up a thermal environment. In this way we can associate an operationally meaningful notion of temperature to any quantum density matrix. We provide general expressions for these effective temperatures, for both single- and many-copy systems, establishing connections to concepts previously discussed in the literature. Finally, we consider a more sophisticated scenario where the heat exchange between the system and the thermal environment is assisted by a quantum reference frame. This leads to an effect of "coherent quantum catalysis", where the use of a coherent catalyst allows for exploiting quantum energetic coherences in the system, now leading to much colder or hotter effective temperatures.