The effect of photo-generated carriers on the spectral diffusion of a quantum dot coupled to a photonic crystal cavity

TL;DR

This paper demonstrates that photo-generated carriers can significantly reduce spectral diffusion in quantum dot-photonic crystal cavity systems, potentially enabling narrower linewidths for quantum information applications.

Contribution

It provides experimental evidence that photo-generated carriers suppress charge fluctuations, reducing spectral diffusion and linewidth broadening in quantum dot-cavity systems.

Findings

Spectral diffusion is partly caused by charge fluctuations on etched surfaces.

Photo-generated carriers can suppress these charge fluctuations.

Linewidth reduction by a factor of ~2 was observed with photo-generated carriers.

Abstract

We experimentally observe the effect of photo-generated carriers on the spectral diffusion of a quantum dot (QD) coupled to a photonic crystal (PC) cavity. In this system, spectral diffusion arises in part from charge fluctuations on the etched surfaces of the PC. We find that these fluctuations may be suppressed by photo-generated carriers, leading to a reduction of the measured QD linewidth by a factor of ~2 compared to the case where the photo-generated carriers are not present. This result demonstrates a possible means of countering the effects of spectral diffusion in QD-PC cavity systems and thus may be useful for quantum information applications where narrow QD linewidths are desired.