Incompressible polaritons in a flat band

TL;DR

This paper explores how geometric frustration in a driven photonic lattice can induce strongly correlated, incompressible photon states with crystalline order, using a circuit QED setup.

Contribution

It demonstrates engineering strong photonic correlations in a non-equilibrium system via frustration-induced kinetic energy quenching, revealing a novel incompressible flat band polariton state.

Findings

Incompressible photon state with short-range crystalline order

Strong spatial correlations with anti-bunching and density-wave oscillations

Proposed tunable circuit QED implementation

Abstract

We study the interplay of geometric frustration and interactions in a non-equilibrium photonic lattice system exhibiting a polariton flat band as described by a variant of the Jaynes-Cummings-Hubbard model. We show how to engineer strong photonic correlations in such a driven, dissipative system by quenching the kinetic energy through frustration. This produces an incompressible state of photons characterized by short-ranged crystalline order with period doubling. The latter manifests itself in strong spatial correlations, i.e., on-site and nearest-neighbor anti-bunching combined with extended density-wave oscillations at larger distances. We propose a state-of-the-art circuit QED realization of our system, which is tunable in situ.