Dike states in multiple quantum dots

TL;DR

This paper theoretically investigates collective optical effects in small groups of quantum dots, identifying conditions for stable subradiant and superradiant states, and analyzing excitation dynamics with realistic quantum dot parameters.

Contribution

It introduces a model for multiple quantum dots with realistic differences, analyzing collective states and excitation trapping using the Lindblad equation.

Findings

Identification of conditions for stable subradiant and superradiant states.

Demonstration of spontaneous excitation trapping.

Observation of persistent oscillations in steady-state populations.

Abstract

We present a theoretical study of the collective optical effects which can occur in groups of three and four quantum dots. We define conditions for stable subradiant (dark) states, rapidly decaying superradiant states,and spontaneous trapping of excitation. Each quantum dot is treated like a two-level system. The quantum dots are though realistic, meaning that they may have different transition energies and dipole moments. The dots interact via a short-range coupling which allows excitation transfer across the dots, but conserves the total population. We calculate the time evolution of single- and biexciton states using the Linblad equation. In the steady state the individual populations of each dot may have permanent oscillations with frequencies given by the energy separation between the subradiant eigenstates.