Efficient coupling of photons to a single molecule and the observation of its resonance fluorescence

TL;DR

This paper presents a highly efficient method for coupling photons to a single molecule, enabling detailed resonance fluorescence studies, including the first observation of the Mollow triplet from a solid-state emitter and detection at extremely low powers.

Contribution

It introduces a novel detection scheme that captures both coherent and incoherent fluorescence over a wide intensity range, advancing quantum optical investigations with single molecules.

Findings

Observation of the Mollow triplet from a single solid-state emitter.

Detection of single molecules with incident power as low as 150 attoWatts.

Exploration of resonance fluorescence over 9 orders of magnitude of excitation intensity.

Abstract

Single dye molecules at cryogenic temperatures display many spectroscopic phenomena known from free atoms and are thus promising candidates for fundamental quantum optical studies. However, the existing techniques for the detection of single molecules have either sacrificed the information on the coherence of the excited state or have been inefficient. Here we show that these problems can be addressed by focusing the excitation light near to the absorption cross section of a molecule. Our detection scheme allows us to explore resonance fluorescence over 9 orders of magnitude of excitation intensity and to separate its coherent and incoherent parts. In the strong excitation regime, we demonstrate the first observation of the Mollow triplet from a single solid-state emitter. Under weak excitation we report the detection of a single molecule with an incident power as faint as 150 attoWatt, paving the way for studying nonlinear effects with only a few photons.