Towards Strong Coupling of Surface Plasmons and Quantum Dot Excitons

Santhosh Kotni Chemical Physics, Weizmann Institute of Science, Rehovot, Israel Nir Zohar Chemical Physics, Weizmann Institute of Science, Rehovot, Israel Ora Bitton Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel Tamar Seideman Department of Chemistry, Northwestern University, Evanston, Illinois, USA Maxim Sukharev School of Letters and Sciences, Arizona State University, Mesa, Arizona, USA Gilad Haran Chemical Physics, Weizmann Institute of Science, Rehovot, Israel

Due to their ability to confine light into nanometer sized volumes, plasmonic metal nanostructures have been successfully used for improving the sensitivity of molecular fluorescence and Raman spectroscopies. A current frontier of molecular plasmonics is the investigation of strong coupling of molecular excitations to surface plasmons, which can pave the way to applications such as quantum information processing and single-photon sources. Though some studies on strong coupling between organic molecular aggregates and plasmonic structures have appeared in the literature recently, no experiments involving individual quantum emitters have so far been reported. Here we employ semiconductor quantum dots (QDs) as quantum emitters coupled to silver dimer nanoantennas. QDs have several advantages over organic molecules including a larger transition dipole moment and a longer chemical lifetime. We develop methods based on e-beam lithography to fabricate dimer nanoantennas and position QDs within their gaps. The plasmonic properties of every single nanoantenna are characterized by dark-field microspectroscopy. Initial results indicate that the strong coupling regime is indeed achieved with our devices. Calculations using a quantum Liouville-Maxwell approach are being carried out on the system to obtain a better understanding of the origin and implications of the observed phenomena.

santoshkotni@gmail.com