Spontaneous symmetry breaking in a coherently driven nanophotonic Bose-Hubbard dimer

TL;DR

This paper reports the first experimental observation of spontaneous mirror symmetry breaking in coherently driven nanophotonic cavities, revealing new phenomena in coupled photonic systems with potential for studying chaos and quantum correlations.

Contribution

It demonstrates spontaneous symmetry breaking in a photonic crystal nanocavity system with negative photon hopping, a novel experimental realization of SSB in driven-dissipative photonic systems.

Findings

SSB observed as intensity localization in one cavity

SSB occurs over a wide parameter space of drive and detuning

Identification of a bistable symmetric region

Abstract

We report on the first experimental observation of spontaneous mirror symmetry breaking (SSB) in coherently driven-dissipative coupled optical cavities. SSB is observed as the breaking of the spatial or mirror Z2 symmetry between two symmetrically pumped and evanescently coupled photonic crystal nanocavities, and manifests itself as random intensity localization in one of the two cavities. We show that, in a system featuring repulsive boson interactions (U > 0), the observation of a pure pitchfork bifurcation requires negative photon hopping energies (J < 0), which we have realized in our photonic crystal molecule. SSB is observed over a wide range of the two-dimensional parameter space of driving intensity and detuning, where we also find a region that exhibits bistable symmetric behavior. Our results pave the way for the experimental study of limit cycles and deterministic chaos arising from SSB, as well as the study of nonclassical photon correlations close to SSB transitions.