Reducing phonon-induced decoherence in solid-state single-photon sources with cavity quantum electrodynamics

TL;DR

This paper demonstrates that coupling semiconductor quantum dots to high-Q microcavities significantly enhances photon indistinguishability by mitigating phonon-induced decoherence, with both theoretical and experimental validation across various temperatures.

Contribution

It provides a combined theoretical and experimental analysis showing how cavity quantum electrodynamics can reduce phonon effects in solid-state single-photon sources, offering design guidelines for optimal cavity structures.

Findings

Indistinguishability exceeds 97% up to 18 K with cavity coupling.

Cavity redirects phonon sidebands, improving full spectrum indistinguishability.

Photon indistinguishability reaches over 99% at 0 K and 76% at 20 K with cavity effects.

Abstract

Solid-state emitters are excellent candidates for developing integrated sources of single photons. Yet, phonons degrade the photon indistinguishability both through pure dephasing of the zero-phonon line and through phonon-assisted emission. Here, we study theoretically and experimentally the indistinguishability of photons emitted by a semiconductor quantum dot in a microcavity as a function of temperature. We show that a large coupling to a high quality factor cavity can simultaneously reduce the effect of both phonon-induced sources of decoherence. It first limits the effect of pure dephasing on the zero phonon line with indistinguishabilities above $97\%$ up to $18$ K. Moreover, it efficiently redirects the phonon sidebands into the zero-phonon line and brings the indistinguishability of the full emission spectrum from $87\%$ (resp. $24\%$) without cavity effect to more than $99\%$ (resp. $76\%$) at $0$ K (resp. $20$ K). We provide guidelines for optimal cavity designs that further minimize the phonon-induced decoherence.