First-order coherent resonant tunneling through an interacting coupled-quantum-dot interferometer: generic quantum rate equations and current noise

摘要

We carry out a detailed analysis of coherent resonant tunneling through twocoupled quantum dots (CQD) in a parallel arrangement in the weak tunnelinglimit. We establish a set of quantum rate equations (QREs) in terms of theeigenstate-representation by means of a generic quantum Langevin equationapproach, which is valid for arbitrary bias-voltage, temperature, and interdothopping strength. Based on linear-response theory, we further derive thecurrent and frequency-independent shot noise formulae. Our results reveal thata previously used formula for evaluating Schottky-type noise of a "classical"single-electron transistor is a direct result of linear-response theory, and itremains applicable for small quantum devices with internal coupling. Ournumerical calculations show some interesting transport features (i) for aseries-CQD: the appearance of a NDC due to the bias-voltage-induced shifting ofbare levels or a finite interdot Coulomb repulsion, and (ii) for a parallel CQDin strong interdot Coulomb repulsion regime: finite-bias-induced ABoscillations of current, and magnetic-flux-controllable negative differentialconductance and a huge Fano factor.