Lecture: Coherent Spectroscopy of Single Molecules in the Near-Field of Plasmonic Nanoantennas

26.07.2017, 14:00

Benjamin Gmeiner, Harvard University, Cambridge, MA, USA


Seminar Room A1.500, MPL, Staudtstr. 2, 91058 Erlangen


Abstract:

In this talk, I will discuss the first steps to develop coherent spectroscopy and microscopy of single quantum emitters in the near-field of plasmonic nanoantennas.

Nanoantennas are the analogue of radio or microwave antennas in the optical regime and offer the potential to control and manipulate optical fields at the nanometer scale. Placing single quantum systems inside the hotspot of a nanoantenna allows for strong control over their emission properties. Extensive research into optical nanoantennas has been directed mostly towards incoherent effects. However, if a single quantum system is coupled to a plasmonic structure, fascinating and abundant, coherent properties can arise.

At cryogenic temperatures, molecules can possess a lifetime-limited linewidth and serve as a general model for a quantum mechanical two-level system. We combine cryogenic high-resolution spectroscopy with localization microscopy to identify and study narrow resonances of single molecules coupled to nanofabricated plasmonic gold spheres. The spectral and spatial behaviour of coherent extinction spectra recorded from the composite molecule-nanoantenna system, leading to Fano profiles in the far-field signal are discussed. We observe clear signals on coherent coupling of single molecules and plasmonic nanoantennas. However, optical data on thousands of molecules indicate the limits of the stability of molecules near nanostructures.