纳米尺度含时输运中的几何效应和信号延迟
Geometrical effects and signal delay in time-dependent transport at the nanoscale
摘要：
本文用约化密度算符方法研究了介观样品通过含时势垒与粒子库相连时的非稳态输运。广义主方程通过考虑记忆核的Crank-Nicolson算法求解，该记忆核体现了通常被忽略的非马尔可夫效应。我们提出了一个物理上合理的铅样品耦合模型，该模型考虑了入射电子的能量与隔离样品的能级之间的匹配，以及它们在接触处的重叠。使用紧束缚描述的系统，我们调查的样品的光谱结构和其本征函数的本地化特性的瞬态电流中引起的影响。在强磁场中，瞬态电流沿边缘态传播。人口和凝聚力的行为进行了讨论，以及它们的连接隧道的过程是相关的运输。
英文摘要：
The nonstationary and steady-state transport through a mesoscopic sample connected to particle reservoirs via time-dependent barriers is investigated within the reduced density operator method. The generalized Master equation is solved via the Crank-Nicolson algorithm by taking into account the memory kernel which embodies the non-Markovian effects that are commonly disregarded. We propose a physically reasonable model for the lead-sample coupling which takes into account the match between the energy of the incident electrons and the levels of the isolated sample, as well as their overlap at the contacts. Using a tight-binding description of the system we investigate the effects induced in the transient current by the spectral structure of the sample and by the localization properties of its eigenfunctions. In strong magnetic fields the transient currents propagate along edge states. The behavior of populations and coherences is discussed, as well as their connection to the tunneling processes that are relevant for transport.
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