Optical blocking of electron tunneling into a single self-assembled quantum dot

TL;DR

This study uses time-resolved resonance fluorescence to investigate electron tunneling in a single quantum dot, revealing optical blocking effects that reduce tunneling rates when the dot is exciton-occupied.

Contribution

It demonstrates optical blocking of electron tunneling in a single quantum dot, combining experimental RF measurements with a master equation model.

Findings

Tunneling rate is independent of reservoir occupation.

Optical excitation reduces electron tunneling rate when exciton is present.

Experimental data explained by a model including optical blocking.

Abstract

Time-resolved resonance fluorescence (RF) is used to analyse electron tunneling between a single self-assembled quantum dot (QD) and an electron reservoir. In equilibrium, the RF intensity reflects the average electron occupation of the QD and exhibits a gate voltage dependence that is given by the Fermi distribution in the reservoir. In the time-resolved signal, however, we find that the relaxation rate for electron tunneling is independent of the occupation in the charge reservoir. Using a master equation approach which includes both the electron tunneling and the optical excitation/recombination, we are able to explain the experimental data by optical blocking, i. e. a reduced electron tunneling rate when the QD is occupied by an exciton.