Coherent versus Incoherent Light Scattering from a Quantum Dot

TL;DR

This paper investigates the spectral properties of light scattered by a single quantum dot, distinguishing between coherent and incoherent scattering, and explores how spectral diffusion and excitation conditions affect coherence.

Contribution

It provides detailed analysis of the scattering mechanisms in a quantum dot, demonstrating conditions for near-perfect coherence and examining the impact of spectral diffusion.

Findings

Coherent scattering fraction approaches unity at weak or detuned excitation.

Spectral diffusion influences spectra and phase coherence, masking ideal two-level behavior.

Pure dephasing is not a dominant decoherence mechanism in this system.

Abstract

We analyze the light scattered by a single InAs quantum dot interacting with a resonant continuous-wave laser. High resolution spectra reveal clear distinctions between coherent and incoherent scattering, with the laser intensity spanning over four orders of magnitude. We find that the fraction of coherently scattered photons can approach unity under sufficiently weak or detuned excitation, ruling out pure dephasing as a relevant decoherence mechanism. We show how spectral diffusion shapes spectra, correlation functions, and phase-coherence, concealing the ideal radiatively-broadened two-level system described by Mollow.