Enhanced control of single-molecule emission frequency and spectral diffusion

TL;DR

This paper demonstrates a two-dimensional electric field control method to tune single-molecule emission frequencies while suppressing spectral diffusion, enhancing emitter stability for quantum applications.

Contribution

It introduces a novel 2D electric field control technique that simultaneously tunes emission frequency and reduces spectral fluctuations in single-molecule emitters.

Findings

Electric field tuning can shift emission frequencies.

Two-dimensional control suppresses spectral diffusion.

Enhanced emitter stability at cryogenic temperatures.

Abstract

The Stark effect provides a powerful method to shift the spectra of molecules, atoms and electronic transitions in general, becoming one of the simplest and most straightforward way to tune the frequency of quantum emitters by means of a static electric field. At the same time, in order to reduce the emitter sensitivity to charge noise, inversion symmetric systems are typically designed, providing a stable emission frequency, with a quadratic-only dependence on the applied field. However, such nonlinear behaviour might reflect in correlations between the tuning ability and unwanted spectral fluctuations. Here, we provide experimental evidence of this trend, using molecular quantum emitters in the solid state cooled down to liquid helium temperatures. We finally combine the electric field generated by electrodes, which results parallel to the molecule induced dipole, to optically excite long-lived charge states, acting in the perpendicular direction. Based on the anisotropy of the molecule's polarizability, our two-dimensional control of the local electric field allows not only to tune the emitter's frequency but also to sensibly suppress the spectral instabilities associated to field fluctuations.