Exciton-polaritons (polaritons herein) are bosonic quasiparticles with unique physical properties arising from strong coupling between excitons and confined photons. Since their first demonstration, exciton-polaritons became a convenient platform for studies of collective quantum effects such as Bose-Einstein condensation and superfluidity.
To date, the most striking effects were cleanly demonstrated in GaAs- based microcavities due to the very low defect densities in those MBE-grown structures. However, polaritons in GaAs quantum wells can only exist at cryogenic temperatures, which limits practical applications for future optoelectronics. To overcome this limitation, FLEET is pushing towards room temperature operation by utilizing the more stable excitons in monolayers of transition metal dichalcogenide crystals (TMDCs). Polariton condensation and superfluidity in this material class can potentially allow dissipationless transport at room temperature and form the basis for future optoelectronic devices with ultra-low energy consumption.
In this talk I will demonstrate the methods we are using in FLEET’s theme II to make high-quality optical microcavities operating in the strong coupling regime between the excitons in the TMDC WS2 and the cavity photons at room temperature. Further, I will give an update on the first observations we have made in such a structure, which include signatures of ballistic polariton flow at room temperature and power dependent redistribution of trapped polaritons into their ground state. This results manifest a milestone in FLEET’s mission towards realizing polariton condensation and superflow in atomically thin semiconductor.
About the presenter
Matthias is a PhD student studying optoelectronics and exciton-polaritons with A/Prof Elena Ostrovskaya at the Australian National University. Working closely with FLEET colleagues at RMIT and Monash, Matthias is aiming to achieve polariton-condensation at room temperature in optical microcavities with embedded 2D materials, and realising superfluidity at room temperature – within FLEET’s research theme 2: exciton superfluids. His past experience spans design, fabrication and characterisation of novel optoelectronic devices, optical spectroscopy, and pulse shaping as well as theoretical simulation and implementation of reconstructive measurement techniques.