Non-equilibrium current and relaxation dynamics of a charge-fluctuating quantum dot

¹  Institut für Theoretische Physik A and JARA-Fundamentals of Future Information Technology, RWTH Aachen University - D-52056 Aachen, Germany, EU
²  Physikalisches Institut, Universität Bonn - D-53115 Bonn, Germany, EU

Corresponding author: karrasch@physik.rwth-aachen.de

Received: 11 March 2010
Accepted: 22 April 2010

Abstract

We study the steady-state current in a minimal model for a quantum dot dominated by charge fluctuations and analytically describe the time evolution into this state. The current is driven by a finite-bias voltage V across the dot, and two different renormalization group methods are used to treat small-to-intermediate local Coulomb interactions. The corresponding flow equations can be solved analytically, which allows to identify all microscopic cutoff scales. Exploring the entire parameter space we find rich non-equilibrium physics which cannot be understood by simply considering the bias voltage as an infrared cutoff. For the experimentally relevant case of left-right asymmetric couplings, the current generically shows a power law suppression for large V. The relaxation dynamics towards the steady state features characteristic oscillations as well as an interplay of exponential and power law decay.