Polaritons: Tuning Topology & Localisation

Thomas Sturges
June 3rd, 2019 THOMAS STURGES University of Warsaw

I will discuss two main topics, that provide an overview of my current research directions.

1) Manipulating Type-I and Type-II Dirac Polaritons in Cavity-Embedded Honeycomb Metasurfaces

I will show that one can alter the topological phases of polaritons simply by tuning the light-matter coupling strength. A honeycomb array of meta-atoms embedded in a photonic cavity hosts both conventional type-I Dirac points, but also type-II Dirac points, due to a non-trivial winding in the light-matter coupling. We will see that we can merge these points solely by changing the height of the photonic cavity. This allows us to morph Dirac polaritons from massless to massive, as well as inverting their chirality. These results are realisable in various physical systems and should give rise to unexplored Dirac-related phenomena and unconventional transport properties.

2) Localisation of Microcavity Polaritons

In closed systems, thermodynamics foresees that all evolutions lead to an equilibrium state. However this notion was recently challenged by the demonstration of many-body localisation, which arises among the interplay of disorder-induced localisation and many-body interactions. We ask the question: can a localised phase exist in an open, interacting, driven-dissipative system. In collaboration with an experimental group from EPFL we demonstrate the localisation of microcavity polaritons, as witnessed by the inverse participation-ratio.

Seminar, June 3, 2019, 10:15. ICFO’s Seminar Room

Hosted by Prof. Maciej Lewenstein