Thielmann Axel, Hettler Matthias H, König Jürgen, Schön Gerd
Forschungszentrum Karlsruhe, Institut für Nanotechnologie, 76021 Karlsruhe, Germany.
Phys Rev Lett. 2005 Sep 30;95(14):146806. doi: 10.1103/PhysRevLett.95.146806.
We derive general expressions for the current and the shot noise, taking into account non-Markovian memory effects. In generalization of previous approaches, our theory is valid for an arbitrary Coulomb interaction and coupling strength and is applicable to quantum dots and more complex systems such as molecules. A fully consistent diagrammatic expansion up to second order in the coupling strength, taking into account cotunneling processes, allows for a study of transport in an intermediate coupling strength regime relevant to many current experiments. We discuss a single-level quantum dot as a first example, focusing on the Coulomb-blockade regime where the cotunneling processes dominate. We find super-Poissonian shot noise due to inelastic spin-flip cotunneling processes at an energy scale different from the one expected from first-order calculations.
我们推导了考虑非马尔可夫记忆效应时电流和散粒噪声的一般表达式。与先前方法不同的是，我们的理论适用于任意库仑相互作用和耦合强度，并且适用于量子点以及更复杂的系统，如分子。在考虑共隧穿过程的情况下，耦合强度二阶以内的完全一致的图解展开，使得我们能够研究与许多当前实验相关的中间耦合强度 regime 下的输运。我们以单能级量子点为例进行讨论，重点关注共隧穿过程占主导的库仑阻塞 regime。我们发现，在与一阶计算预期不同的能量尺度上，由于非弹性自旋翻转共隧穿过程，散粒噪声呈现超泊松分布。
