标题： 通过非对易算符和强耦合效应的最优量子比特介导的量子热传递 显示英文标题

标题： Optimal qubit-mediated quantum heat transfer via noncommuting operators and strong coupling effects

摘要： 热传递在量子系统中是一个当前感兴趣的主题，因为新兴的量子技术试图缩小发动机的尺寸并研究热力学的基本方面。 在本工作中，我们考虑两个热库之间的热传递，其中中心自旋自由度介导该过程。 我们的目标是确定能够最大化任意系统-环境耦合强度下的热传递的系统-环境耦合算符。 通过采用形式为反应坐标映射的马尔可夫嵌入方法，我们数值研究了任意系统-环境耦合能量以及热库与中心量子比特系统之间的一般系统-环境耦合算符的热传递。 我们发现，对于最优热传递所需的条件存在显著差异，这取决于系统是弱耦合还是强耦合到热库。 在弱耦合区域，最优热传递需要相同的耦合算符，这些算符促进最大顺序传输，并与中心量子比特共振。 相反，在强耦合区域，热库和冷库之间的非对易系统-环境耦合算符是实现最优热传递所必需的。 我们进一步采用有效哈密顿量理论，并获得对所观察现象的部分解析见解。 我们讨论了这种近似方法在捕捉非对易耦合算符的热流行为方面的局限性，呼吁未来对其进行扩展，以捕捉具有通用相互作用哈密顿量的系统的传输特性。 显示英文摘要

摘要： Heat transfer in quantum systems is a current topic of interest due to emerging quantum technologies that attempt to miniaturize engines and examine fundamental aspects of thermodynamics. In this work, we consider heat transfer between two thermal reservoirs in which a central spin degree of freedom mediates the process. Our objective is to identify the system-bath coupling operators that maximize heat transfer at arbitrary system-bath coupling strengths. By employing a Markovian embedding method in the form of the reaction-coordinate mapping, we study numerically heat transfer at arbitrary system-bath coupling energy and for general system-bath coupling operators between the baths and the central qubit system. We find a stark contrast in the conditions required for optimal heat transfer depending on whether the system is weakly or strongly coupled to the heat baths. In the weak-coupling regime, optimal heat transfer requires identical coupling operators that facilitate maximum sequential transport, resonant with the central qubit. In contrast, in the strong-coupling regime, noncommuting system-bath coupling operators between the hot and cold reservoirs are necessary to achieve optimal heat transfer. We further employ the Effective Hamiltonian theory and gain partial analytical insights into the observed phenomena. We discuss the limitations of this approximate method in capturing the behavior of the heat current for noncommuting coupling operators, calling for its future extensions to capture transport properties in systems with general interaction Hamiltonians.