Single exciton emission from gate-defined quantum dots

Abstract

With gate-defined electrostatic traps fabricated on a double quantum well we are able to realize an optically active and voltage-tunable quantum dot confining individual, long-living, spatially indirect excitons. We study the transition from multi excitons down to a single indirect exciton. In the few exciton regime, we observe discrete emission lines reflecting the interplay of dipolar interexcitonic repulsion and spatial quantization. The quantum dot states are tunable by gate voltage and employing a magnetic field results in a diamagnetic shift. The scheme introduces a new gate-defined platform for creating and controlling optically active quantum dots and opens the route to lithographically defined coupled quantum dot arrays with tunable in-plane coupling and voltage-controlled optical properties of single charge and spin states.

Spin–orbit-induced hole spin relaxation in InAs and GaAs quantum dots

“…2(b-c) show the spin lifetime dependence on the vertical confinement in QDs with moderately strong and weak lateral confinement, respectively. These confinement strengths roughly correspond to self-assembled (panel (b)) [46,47] and electrostatic (panel (c)) [48] QDs. As can be seen in Fig.…”

Observation of macroscopic coherence in self-organized dipolar excitons

“…2.a shows that the high energy side of the emission is narrowed while T b is decreased whereas the low energy side is broadened. Such spectral asymmetry has been reported very recently in microscopic traps [15,27]. Its establishment at very low temperatures was then interpreted as a manifestation for strong dipolar correlations between indirect excitons at densities of the order of 10 10 cm −2 [15].…”