Cavity-induced many-body localization

Many-body cavity QED is an interesting platform for realizing non-ergodic physics, enabling the competition of local interactions between particles and global interactions mediated by the cavity. Here, we explore non-ergodicity – specifically many-body localization – in the context of cavity QED at strong coupling. Working with a spinless electronic Hubbard chain sitting coupled to a single-mode cavity, we show that the global coupling between electrons and photons, which generally is expected to delocalize the fermionic excitations, can instead favor the appearance of localization. This is supported by a strong coupling high-frequency expansion as well as numerical calculations in both single particle and many-body regimes. We find evidence that (prethermal) many-body localization may survive strong quantum fluctuations of the photon number by exploring energy dependence, seeing signatures of localization down to photon numbers as small as n = 2.