Phase Coherent Oscillations of Excitonic Photocapacitance and Bose-Einstein Condensation in Quantum Coupled 0D-2D Heterostructure

TL;DR

This paper demonstrates quantum coherent oscillations and Bose-Einstein condensation of excitons in a novel 0D-2D heterostructure, revealing strong coupling effects and potential for high-temperature excitonic BEC.

Contribution

It reports the first observation of quantum coherent oscillations and excitonic Bose-Einstein condensation in a coupled quantum dot and quantum well heterostructure, highlighting new pathways for high-temperature quantum states.

Findings

Observation of quantum coherent oscillations of photocapacitance.

Evidence of excitonic Bose-Einstein condensation at low temperatures.

Potential for excitonic BEC at higher temperatures in engineered heterostructures.

Abstract

We report quantum coherent oscillations of photocapacitance of a double-barrier resonant tunneling heterostructure with bias at 10 K. Periodic presence and absence of sharp excitonic transitions in photocapacitance spectra with increasing bias demonstrate strong coupling between InAs quantum dots (0D) and triangular GaAs quantum well (2D). Coherent resonant tunneling in this 0D-2D heterostructure establishes the momentum space narrowing of excitonic Bose-Einstein Condensation. Drastic increase of indirect exciton densities below 70 K reveal that excitonic wave functions anchored with each InAs quantum dots can laterally overlap across wide region around 200 micron to create a macroscopic quantum state of excitonic Bose-Einstein condensate. This itself points out the difficulties encountered in the usual 2D-2D bilayers and coupled quantum well samples used earlier to study excitonic BEC. Finally, we predict how coupled quantum-dots and quantum-well heterostructures can display excitonic Bose-Einstein condensation at even higher temperatures.