Alejandro Giacomotti
Center for Nanoscience and Nanotechnology (C2N)
CNRS-University Paris Saclay (UMR 9001)

“Bifurcations in coupled photonic crystal nanocavities”

Coupled optical nanocavity systems are appealing test-beds for few photon nonlinearities in the context of nonlinear and quantum optics. In this talk I will focus on active nanophotonic devices, specifically two evanescently coupled semiconductor photonic crystal nanocavities, which can be engineered to experimentally access nonlinear transitions –or bifurcations– with moderate-to-low intracavity photon numbers (n~100). I will discuss our recent results on two key bifurcations: spatial inversion (pitchfork) with either incoherent pump or coherent resonant excitation, and time translation (Hopf) symmetry breaking. Importantly, spontaneous symmetry breaking under coherent excitation has been recently predicted to exhibit photon entanglement, paving the way of a new field of research at the interface between classical nonlinear dynamics and quantum optics.

The underlying nanophotonic structure enables a high degree of control, for instance in terms of intercavity coupling parameters, with high photonic integration capabilities. In sum, these ultralow energy devices are versatile building-blocks to realize nanocavity arrays, opening up interesting prospects in the study nonlinear and non-Hermitian optical cavity networks, both in classical and few photon regimes.