Abstract

When cooled to liquid helium temperature, organic molecules demonstrate remarkable optical properties. Over the past three decades, these have been exploited in different single-molecule quantum optical settings, including coherent near-field measurements, far-field realization of efficient extinction, various nonlinear studies as well as single-molecule strong coupling in a microcavity. More recently, we have also reported on cooperative coherent interaction of several individual molecules via a common cavity mode. I will discuss a new line of experiments in which we explore the interaction of molecules with the phononic degrees of freedom of their surrounding matrix. In particular, I will show how a single molecule can act as a nanothermometer with unprecedented sub-milliKelvin sensitivity. If time allows, I will also present new data on Fourier-limited transitions of single molecules on the surface of a crystal and the potential of combining this high spectral resolution with angstrom spatial resolution in scanning probe microscopy.