Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, CNRS-UdS, 23 rue du Loess, B.P. 43, 67034 Strasbourg Cedex 2, France.
Phys Rev Lett. 2010 Oct 15;105(16):166802. doi: 10.1103/PhysRevLett.105.166802. Epub 2010 Oct 11.
The conductance change due to a local perturbation in a phase-coherent nanostructure is calculated. The general expressions to first and second order in the perturbation are applied to the scanning gate microscopy of a two-dimensional electron gas containing a quantum point contact. The first-order correction depends on two scattering states with electrons incoming from opposite leads and is suppressed on a conductance plateau; it is significant in the step regions. On the plateaus, the dominant second-order term likewise depends on scattering states incoming from both sides. It is always negative, exhibits fringes, and has a spatial decay consistent with experiments.
计算了相干纳米结构中局部微扰引起的电导变化。将一阶和二阶微扰的一般表达式应用于包含量子点接触的二维电子气的扫描门显微镜。一阶修正取决于从两个相反的引线进入的两个散射态，并且在电导平台上受到抑制;它在阶跃区域中很重要。在平台上，主导的二阶项同样取决于从两侧进入的散射态。它总是负的，表现出条纹，并且具有与实验一致的空间衰减。
