Sub-Natural Linewidth Single Photons from a Quantum Dot

TL;DR

This paper demonstrates a method to generate single photons with sub-natural linewidth and high coherence from a quantum dot by operating in the Heitler regime, enabling advances in quantum communication and computing.

Contribution

It introduces a novel approach to produce highly coherent single photons from quantum dots using resonance fluorescence in the Heitler regime.

Findings

Achieved 30-fold reduction in photon bandwidth compared to the quantum dot transition linewidth.

Generated photons exhibit high coherence inherited from the excitation laser.

Maintained strong antibunching behavior with low two-photon scattering probability.

Abstract

The observation of quantum dot resonance fluorescence enabled a new solid-state approach to generating single photons with a bandwidth almost as narrow as the natural linewidth of a quantum dot transition. Here, we operate in the Heitler regime of resonance fluorescence to generate sub-natural linewidth and high-coherence quantum light from a single quantum dot. The measured single-photon bandwidth exhibits a 30-fold reduction with respect to the radiative linewidth of the QD transition and the single photons exhibit coherence properties inherited from the excitation laser. In contrast, intensity-correlation measurements reveal that this photon source maintains a high degree of antibunching behaviour on the order of the transition lifetime with vanishing two-photon scattering probability. This light source will find immediate applications in quantum cryptography, measurement-based quantum computing and, in particular, deterministic generation of high-fidelity distributed entanglement among independent and even disparate quantum systems.