An artificial Rb atom in a semiconductor with lifetime-limited linewidth

TL;DR

This paper demonstrates a solid-state single-photon source using a GaAs quantum dot with lifetime-limited linewidths, spectrally matched to Rb atoms, enabling hybrid quantum systems with minimal environmental noise.

Contribution

It introduces a quantum dot source with lifetime-limited linewidths matched to Rb transitions, facilitating hybrid quantum systems with high spectral purity and low environmental noise impact.

Findings

Quantum dot linewidths of 1.48 GHz achieved

Resonance fluorescence dominated by Rayleigh scattering

Low environmental dephasing and MHz blinking rates

Abstract

We report results important for the creation of a best-of-both-worlds quantum hybrid system consisting of a solid-state source of single photons and an atomic ensemble as quantum memory. We generate single photons from a GaAs quantum dot (QD) frequency-matched to the Rb D2-transitions and then use the Rb transitions to analyze spectrally the quantum dot photons. We demonstrate lifetime-limited QD linewidths (1.48 GHz) with both resonant and non-resonant excitation. The QD resonance fluorescence in the low power regime is dominated by Rayleigh scattering, a route to match quantum dot and Rb atom linewidths and to shape the temporal wave packet of the QD photons. Noise in the solid-state environment is relatively benign: there is a blinking of the resonance fluorescence at MHz rates but negligible upper state dephasing of the QD transition. We therefore establish a close-to-ideal solid-state source of single photons at a key wavelength for quantum technologies.