Frequency stabilization of the zero-phonon line of a quantum dot via phonon-assisted active feedback

TL;DR

This paper demonstrates a feedback method to stabilize the emission frequency of a quantum dot's zero-phonon line by using phonon-assisted signals, significantly reducing frequency noise and intensity fluctuations.

Contribution

The authors introduce a novel active feedback technique leveraging phonon-assisted emission to stabilize quantum dot emission frequency without direct zero-phonon line access.

Findings

Zero-phonon fluorescence noise reduced by a factor of 22

Zero-phonon frequency fluctuations reduced by a factor of 7

Feedback bandwidth achieved is 191 Hz

Abstract

We report on the feedback stabilization of the zero-phonon emission frequency of a single InAs quantum dot. The spectral separation of the phonon-assisted component of the resonance fluorescence provides a probe of the detuning between the zero-phonon transition and the resonant driving laser. Using this probe in combination with active feedback, we stabilize the zero-phonon transition frequency against environmental fluctuations. This protocol reduces the zero-phonon fluorescence intensity noise by a factor of 22 by correcting for environmental noise with a bandwidth of 191 Hz, limited by the experimental collection efficiency. The associated sub-Hz fluctuations in the zero-phonon central frequency are reduced by a factor of 7. This technique provides a means of stabilizing the quantum dot emission frequency without requiring access to the zero-phonon emission.