Strong light-matter coupling in disordered systems: multifractality and protected transport
Francesco Mattiotti (Strasbourg University)
When two-level quantum emitters and a cavity mode coherently exchange energy at a rate faster than their decay, the system enters the strong coupling regime of cavity-QED, where light-matter polaritonic states play an important role. Such states are superpositions composed of “bright” emitter modes and cavity photons, while numerous remaining emitter states have no photon contribution, i.e., remain “dark”. Over the past decade, the strong coupling regime has been explored as a tool to engineer fundamental properties of matter such as the chemical reaction rates [1]. Much interest is currently raised by the possibility of modifying energy transport, for which disorder plays a crucial role. While it is well known that coherent transport in disordered media can be inhibited due to Anderson localization of the eigenstates [2], the impact of strong light-matter coupling on Anderson localization has been explored only very recently [3-8]. As a paradigmatic example, I will discuss the spectral and transport properties of the disordered Tavis-Cummings model, showing that the dark states can feature unusual critical properties characterized by extended but non-ergodic (multifractal) wavefunctions [3,5,8].
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