Extinction imaging of a single quantum emitter in its bright and dark states

TL;DR

This paper demonstrates the first room-temperature extinction measurement of a single quantum emitter, enabling detection in both bright and dark states, which advances single-molecule spectroscopy techniques.

Contribution

It introduces a novel method for direct extinction detection of single quantum emitters at ambient conditions, overcoming previous cryogenic limitations.

Findings

First room-temperature extinction measurement of a single quantum emitter

Extinction cross section measured during bright and dark states

Potential for detecting quenched single molecules or atomic clusters

Abstract

Room temperature detection of single quantum emitters has had a broad impact in fields ranging from biophysics to material science, photophysics, or even quantum optics. These experiments have exclusively relied on the efficient detection of fluorescence. An attractive alternative would be to employ direct absorption, or more correctly expressed "extinction" measurements. Indeed, small nanoparticles have been successfully detected using this scheme in reflection and transmission. Coherent extinction detection of single emitters has also been reported at cryogenic temperatures, but their room temperature implementation has remained a great laboratory challenge owing to the expected weak signal-to-noise ratio. Here we report the first extinction study of a single quantum emitter at ambient condition. We obtain a direct measure for the extinction cross section of a single semiconductor nanocrystal both during and in the absence of fluorescence, for example in the photobleached state or during blinking off-times. Our measurements pave the way for the detection and absorption spectroscopy of single molecules or clusters of atoms even in the quenched state.