Critical Theory for the Breakdown of Photon Blockade

Understand

Photon blockade is the result of the interplay between the quantized nature of light and strong optical nonlinearities, whereby strong photon-photon repulsion prevents a quantum optical system from absorbing multiple photons.

• We theoretically study a single atom coupled to the light field, described by the resonantly driven Jaynes--Cummings model, in which case the photon blockade breaks down in a second order phase transition at a critical drive strength.
• We show that this transition is associated to the spontaneous breaking of an anti-unitary PT-symmetry.
• Within a semiclassical approximation we calculate the expectation values of observables in the steady state.