Subject：Nonlinear Optics with semiconductor Rydberg excitons

Speaker：Prof. Thomas Pohl

Emcee：Prof. Guoxiang Huang

Time：9:00am, 25^th Jan, 2018

Place：Science Building A814

About the Speaker：

Thomas Pohl is Niels Bohr Professor at Aarhus University where he leads a group working on theoretical atomic physics, quantum optics and quantum many-body physics. His work has helped establishing several important concepts in the field of Rydberg atom physics, such as the notion of phase transitions to crystalline states, semi-classical approaches to driven-dissipative non-equilibrium dynamics in Rydberg-ensembles or so called Rydberg dressing as recently demonstrated in experiments. Moreover, his group and collaborators have pioneered the theory of quantum nonlinear optics and emerging photon interactions in interacting Rydberg ensembles. Current research interests include the study of exotic many-body physics of different nonlinear quantum photonic systems and ensuing applications.

Abstract：

The realization of exciton-polaritons – hybrid excitations of semiconductor quantum well excitons and cavity photons – has been of great technological and scientific significance. In particular, the short-range collisional interaction between excitons has enabled explorations into a wealth of nonequilibrium and hydrodynamical effects that arise in weakly nonlinear polariton condensates. Yet, the ability to enhance optical nonlinearities would enable quantum photonics applications and open up a new realm of photonic many-body physics in a scalable and engineerable solid-state environment.

In this talk we outline a route to such capabilities in cavity-coupled semiconductors by exploiting the giant interactions between excitons in Rydberg-states. It is demonstrated that optical nonlinearities in such systems can be vastly enhanced by several orders of magnitude and induce nonlinear processes at the level of single photons. As specific realisations we consider semiconducting transition metal dichalcogenide monolayers and apply the developed theory to recent experiments on Rydberg excitons in cuprous oxide semiconductors.