  We study photonic signatures of symmetry broken and topological phases in a
driven, dissipative circuit QED realization of spin-1/2 chains. Specifically,
we consider the transverse-field XY model and a dual model with 3-spin
interactions. The former has a ferromagnetic and a paramagnetic phase, while
the latter features, in addition, a symmetry protected topological phase. Using
the method of third quantization, we calculate the non-equilibrium steady-state
of the open spin chains for arbitrary system sizes and temperatures. We find
that the bi-local correlation function of the spins at both ends of the chain
provides a sensitive measure for both symmetry-breaking and topological phase
transitions of the systems, but no universal means to distinguish between the
two types of transitions. Both models have equivalent representations in terms
of free Majorana fermions, which host zero, one and two topological Majorana
end modes in the paramagnetic, ferromagnetic, and symmetry protected
topological phases, respectively. The correlation function we study retains its
bi-local character in the fermionic representation, so that our results are
equally applicable to the fermionic models in their own right. We propose a
photonic realization of the dissipative transverse-field XY model in a tunable
setup, where an array of superconducting transmon qubits is coupled at both
ends to a photonic microwave circuit.
