Electrically driven cascaded photon-emission in a single molecule

TL;DR

This paper demonstrates electrically driven photon emission from a single molecule using STM, revealing charge-dependent emission and photon cascades, with a model explaining the complex internal dynamics.

Contribution

It introduces a method to control quantum light emission from a single molecule electrically, showing charge-dependent photon emission and cascades, advancing quantum device integration.

Findings

Detection of neutral and charged molecule emission lines with single-photon behavior.

Observation of photon cascade signatures between charged and neutral states.

Control over emission statistics by adjusting charging/discharging rates.

Abstract

Controlling electrically-stimulated quantum light sources (QLS) is key for developing integrated and low-scale quantum devices. The mechanisms leading to quantum emission are complex, as a large number of electronic states of the system impacts the emission dynamics. Here, we use a scanning tunneling microscope (STM) to excite a model QLS, namely a single molecule. The luminescence spectra reveal two lines, associated to the emission of the neutral and positively charged molecule, both exhibiting single-photon source behavior. In addition, we find a correlation between the charged and neutral molecule's emission, the signature of a photon cascade. By adjusting the charging/discharging rate, we can control these emission statistics. This generic strategy is further established by a rate equation model revealing the complex internal dynamics of the molecular junction.