Rudge Samuel L, Kosov Daniel S
College of Science and Engineering, James Cook University, Townsville, QLD, 4814, Australia.
J Chem Phys. 2019 Jul 21;151(3):034107. doi: 10.1063/1.5108518.
In quantum transport through nanoscale devices, fluctuations arise from various sources: the discreteness of charge carriers, the statistical nonequilibrium that is required for device operation, and unavoidable quantum uncertainty. As experimental techniques have improved over the last decade, measurements of these fluctuations have become available. They have been accompanied by a plethora of theoretical literature using many different fluctuation statistics to describe the quantum transport. In this paper, we overview three prominent fluctuation statistics: full counting, waiting time, and first-passage time statistics. We discuss their weaknesses and strengths and explain connections between them in terms of renewal theory. In particular, we discuss how different information can be encoded in different statistics when the transport is nonrenewal and how this behavior manifests in the measured physical quantities of open quantum systems. All theoretical results are illustrated via a demonstrative transport scenario, a Markovian master equation for a molecular electronic junction with electron-phonon interactions. We demonstrate that to obtain nonrenewal behavior, and thus to have temporal correlations between successive electron tunneling events, there must be a strong coupling between tunneling electrons and out-of-equilibrium quantized molecular vibrations.
在通过纳米级器件的量子输运中，涨落源于多种因素：电荷载流子的离散性、器件运行所需的统计非平衡态以及不可避免的量子不确定性。在过去十年里，随着实验技术的进步，对这些涨落的测量已成为可能。与此同时，出现了大量使用多种不同涨落统计来描述量子输运的理论文献。在本文中，我们概述三种突出的涨落统计：全计数统计、等待时间统计和首次通过时间统计。我们讨论它们的优缺点，并根据更新理论解释它们之间的联系。特别是，我们讨论当输运是非更新过程时，不同的信息如何编码在不同的统计中，以及这种行为如何在开放量子系统的测量物理量中体现。所有理论结果都通过一个演示性的输运场景进行说明，即一个具有电子 - 声子相互作用的分子电子结的马尔可夫主方程。我们证明，为了获得非更新行为，从而在连续电子隧穿事件之间存在时间相关性，隧穿电子与非平衡态量子化分子振动之间必须有强耦合。
