Vacuum-induced coherence in quantum dot systems

TL;DR

This paper theoretically investigates vacuum-induced coherence in coupled quantum dots, demonstrating conditions for exciton trapping despite energy mismatches and phonon interactions, highlighting potential for quantum information applications.

Contribution

It provides a detailed analysis of how vacuum-induced coherence can be realized in quantum dot systems considering realistic factors like energy mismatch and phonons.

Findings

Vacuum-induced coherence enables exciton trapping in quantum dots.

Energy mismatch effects can be mitigated through dipole and coupling interplay.

Phonon effects can be suppressed with appropriate system parameters.

Abstract

We present a theoretical study of vacuum-induced coherence in a pair of vertically stacked semiconductor quantum dots. The process consists in a coherent excitation transfer from a single-exciton state localized in one dot to a delocalized state in which the exciton occupation gets trapped. We study the influence of the factors characteristic of quantum dot systems (as opposed to natural atoms): energy mismatch, coupling between the single exciton states localized in different dots, different and non-parallel dipoles due to subband mixing, as well as coupling to phonons. We show that the destructive effect of the energy mismatch can be overcome by an appropriate interplay of the dipole moments and coupling between the dots which allows one to observe the trapping effect even in a structure with technologically realistic energy splitting on the order of milli-electron-Volts. We also analyze the impact of phonon dynamics on the occupation trapping and show that phonon effects are suppressed in a certain range of system parameters. This analysis shows that the vacuum induced coherence effect and the associated long-living trapped excitonic population can be achieved in quantum dots.