On the cotunneling regime of interacting quantum dots

TL;DR

This paper analyzes the dominant ergodic current in interacting quantum dots coupled to biased leads, focusing on the off-resonant regime, and distinguishes between sequential tunneling and cotunneling contributions, highlighting the impact of electron interactions.

Contribution

It provides a novel approach to compute the ergodic current in interacting quantum dots, explicitly including cotunneling effects and their dependence on initial many-body states.

Findings

Cotunneling current depends on initial many-body configuration in interacting case.

In non-interacting case, current matches the Landauer formula expansion.

Explicit calculations for sequential tunneling and cotunneling contributions.

Abstract

Consider a bunch of interacting electrons confined in a quantum dot. The later is suddenly coupled to semi-infinite biased leads at an initial instant $t=0$. We identify the dominant contribution to the ergodic current in the off-resonant transport regime, in which the discrete spectrum of the quantum dot is well separated from the absolutely continuous spectrum of the leads. Our approach allows for arbitrary strength of the electron-electron interaction while the current is expanded in even powers of the (weak) lead-dot hopping constant $\tau$. We provide explicit calculations for sequential tunneling and cotunneling contributions to the current. In the interacting case it turns out that the cotunneling current depends on the initial many-body configuration of the sample, while in the non-interacting case it does not, and coincides with the first term in the expansion of the Landauer formula w.r.t $\tau$.