Breakdown of polaritons in ultrastrongly coupled nanophotonic systems

Abstract

Light-matter interaction in highly coupled regimes is attracting many interests [1] , [2] , especially in fundamental physics as they can provide a platform to study several predicted quantum phenomena such as the possibility to access virtual squeezed vacuum state containing a finite population of virtual photons in the ground state or super-radiant quantum phase transition. Among several coupled systems, the highest coupling records [3] - [5] have been demonstrated in a system consists of metasurfaces of metallic resonators coupled to Landau level (LL) transitions in a semiconductor quantum well (QW). In such a system, more confinement and enhancement of the electric field by reducing the cavity volume can lead to a higher coupling strength; but there should be a physical or technological limit to this reduction.