Savona, Vincenzo2017-10-092017-10-092017-10-09201710.1103/PhysRevA.96.033826https://infoscience.epfl.ch/handle/20.500.14299/141188WOS:000410589500010We investigate the occurrence of a phase transition, characterized by the spontaneous breaking of a discrete symmetry, in a driven-dissipative Bose-Hubbard lattice in the presence of two-photon coherent driving. The driving term does not lift the original U(1) symmetry completely and a discrete Z(2) symmetry is left. When driving the bottom of the Bose-Hubbard band, a mean-field analysis of the steady state reveals a second-order transition from a symmetric phase to a quasicoherent state with a finite expectation value of the Bose field. For larger driving frequency, the phase diagram shows a third region, where both phases are stable and the transition becomes of first order.Open quantum systemsBose-HubbardIsingPhase transitionsPhotonicsQuantum informationtext::journal::journal article::research article