Resonance fluorescence from an atomic-quantum-memory compatible single photon source based on GaAs droplet quantum dots

TL;DR

This paper demonstrates a GaAs quantum dot single photon source emitting resonance fluorescence compatible with quantum memories, showing narrow linewidth and clear single photon emission suitable for quantum networks.

Contribution

It reports the first narrow linewidth resonance fluorescence from strain-free GaAs droplet quantum dots suitable for quantum memory integration.

Findings

Resonance fluorescence linewidth as narrow as 660 MHz

Clear single photon emission demonstrated

Potential for quantum network applications

Abstract

Single photon sources, which are compatible with quantum memories are an important component of quantum networks. In this article, we show optical investigations on isolated GaAs/Al$_{0.25}$Ga$_{0.75}$As quantum dots grown via droplet epitaxy, which emit single photons on resonance with the Rb-87-D$_2$ line (780 nm). Under continuous wave resonant excitation conditions, we observe bright, clean and narrowband resonance fluorescence emission from such a droplet quantum dot. Furthermore, the second-order correlation measurement clearly demonstrates the single photon emission from this resonantly driven transition. Spectrally resolved resonance fluorescence of a similar quantum dot yields a linewidth as narrow as 660 MHz ($ 2.7~\mu eV $), which corresponds to a coherence time of 0.482 ns. The observed linewidth is the smallest reported so far for strain free GaAs quantum dots grown via the droplet method. We believe that this single photon source can be a prime candidate for applications in optical quantum networks.