在位钉扎势在建立有限量子系统热输运准稳态条件中的作用
Role of the on-site pinning potential in establishing quasi-steady-state conditions of heat transport in finite quantum systems
摘要：
我们通过求解海森堡运动方程研究了有限线性谐振链中的能量输运，并利用非平衡格林函数验证了我们的结果。系统的初始状态由两个独立的有限线性链组成，它们在不同的温度下处于各自的平衡状态。然后将链突然连接以形成复合链。的时间演变的电流从刚刚打开后的瞬态政权，然后到以后的时间是确定的数字。我们期望电流在稍后接近稳态值。令人惊讶的是，这是可能的，只有当一个非零的二次现场钉扎电位施加到链中的每个粒子。如果不存在在位势，则当时间尺度大于声音从中点到链边再返回的旅行时间时，会出现循环现象。推导出瞬态和稳态电流的解析表达式，以进一步阐明现场电位的作用。
英文摘要：
We study the transport of energy in a finite linear harmonic chain by solving the Heisenberg equation of motion, as well as by using nonequilibrium Green's functions to verify our results. The initial state of the system consists of two separate and finite linear chains that are in their respective equilibriums at different temperatures. The chains are then abruptly attached to form a composite chain. The time evolution of the current from just after switch-on to the transient regime and then to later times is determined numerically. We expect the current to approach a steady-state value at later times. Surprisingly, this is possible only if a nonzero quadratic on-site pinning potential is applied to each particle in the chain. If there is no on-site potential a recurrent phenomenon appears when the time scale is longer than the traveling time of sound to make a round trip from the midpoint to a chain edge and then back. Analytic expressions for the transient and steady-state currents are derived to further elucidate the role of the on-site potential.
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