Nonequilibrium Phases of an Incoherently Driven Strongly Correlated Photonic Lattice*

We explore theoretically the physics of a lattice of coupled resonators with giant optical nonlinearities where optical gain is provided by incoherently pumped two-level systems [1]. Within a Gutzwiller mean-field approach, we predict the emergence of a dissipative phase transition associate with the spontaneous breaking of the U(1) symmetry, from a localized Mott-like phase of photons to a coherent delocalized phase, which is akin to a coherent laser of strongly correlated photons. The essence of the mean-field predictions is corroborated by finite-size simulations obtained with matrix product operators [2] and corner-space renormalization [3] methods. An extension of the model, involving the coupling to a reservoir of population-inverted two-level emitters with a broad distribution of transition frequencies, will be discussed [4].

[1] A. Biella, F. Storme, J. Lebreuilly, D. Rossini, R. Fazio, I. Carusotto, and C. Ciuti, Phys. Rev. A 96, 023839 (2017).
[2] M. Zwolak and G. Vidal, Phys. Rev. Lett. 93, 207205 (2004).
[3] S. Finazzi, A. Le Boité, F. Storme, A. Baksic, and C. Ciuti, Phys. Rev. Lett. 115, 080604 (2015).
[4] J. Lebreuilly, A. Biella, F. Storme, D. Rossini, R. Fazio, C. Ciuti, and I. Carusotto, Phys. Rev. A 96, 033828 (2017).