Cavity-enhanced excitation of a quantum dot in the picosecond regime

TL;DR

This paper demonstrates a cavity-based scheme for efficiently exciting a quantum dot with minimal laser leakage, achieving 98% population inversion and elucidating the role of phonons in Rabi oscillations.

Contribution

It introduces a novel cavity mode splitting technique for selective excitation and collection in quantum dots, supported by a combined experimental and theoretical analysis.

Findings

Achieved 98% population inversion in quantum dots.

Demonstrated the dependence of Rabi oscillations on laser detuning.

Included exciton-phonon interactions in the theoretical model, matching experimental results.

Abstract

A major challenge in generating single photons with a single emitter is to excite the emitter while avoiding laser leakage into the collection path. Ideally, any scheme to suppress this leakage should not result in a loss in efficiency of the single-photon source. Here, we investigate a scheme in which a single emitter, a semiconductor quantum dot, is embedded in a microcavity. The scheme exploits the splitting of the cavity mode into two orthogonally-polarised modes: one mode is used for excitation, the other for collection. By linking experiment to theory, we show that the best population inversion is achieved with a laser pulse detuned from the quantum emitter. The Rabi oscillations have an unusual dependence on pulse power. Our theory describes them quantitatively allowing us to determine the absolute photon creation probability. For the optimal laser detuning, the population innversion is 98\%. The Rabi oscillations depend on the sign of the laser-pulse detuning. We show that this arises from the non-trivial effect of phonons on the exciton dynamics. The exciton-phonon interaction is included in the theory and gives excellent agreement with all the experimental results.