Transient Dynamics of Confined Charges in Quantum Dots in the Sequential Tunnelling Regime

TL;DR

This paper explores the transient, non-Markovian quantum dynamics of electrons in multilevel quantum dots during sequential tunneling, highlighting the importance of coherence effects and decoherence times in nonequilibrium conditions.

Contribution

It introduces a microscopic non-Markovian density matrix approach to analyze quantum dot transport, revealing significant differences from Markovian approximations and providing criteria for extended decoherence times.

Findings

Non-Markovian effects significantly influence decoherence and relaxation.

Markovian limit neglects coherent oscillations and underestimates relaxation times.

Criteria for extended decoherence times depend on tunneling anisotropies and energy configurations.

Abstract

We investigate the time-dependent, coherent, and dissipative dynamics of bound particles in single multilevel quantum dots in the presence of sequential tunnelling transport. We focus on the nonequilibrium regime where several channels are available for transport. Through a fully microscopic and non-Markovian density matrix formalism we investigate transport-induced decoherence and relaxation of the system. We validate our methodology by also investigating the Markov limit on our model. We confirm that not only does this limit neglect the coherent oscillations between system states as expected, but also the rate at which the steady state is reached under this limit significantly differs from the non-Markovian results. By a systematic analysis of the decay constants and frequencies of coherent oscillations for the off-diagonal elements of the reduced density matrix under various realistic tunneling rate anisotropies and energy configurations, we outline a criteria for extended decoherence times.