  We describe simulations of the quantum dynamics of a confocal cavity QED
system that realizes an intrinsically driven-dissipative spin glass. A close
connection between open quantum dynamics and replica symmetry breaking is
established, in which individual quantum trajectories are the replicas. We
observe that entanglement plays an important role in the emergence of replica
symmetry breaking in a fully connected, frustrated spin network of up to
fifteen spin-1/2 particles. Quantum trajectories of entangled spins reach
steady-state spin configurations of lower energy than that of semiclassical
trajectories. Cavity emission allows monitoring of the continuous stochastic
evolution of spin configurations, while backaction from this projects entangled
states into states of broken Ising and replica symmetry. The emergence of spin
glass order manifests itself through the simultaneous absence of magnetization
and the presence of nontrivial spin overlap density distributions among
replicas. Moreover, these overlaps reveal incipient ultrametric order, in line
with the Parisi RSB solution ansatz for the Sherrington-Kirkpatrick model. A
nonthermal Parisi order parameter distribution, however, highlights the
driven-dissipative nature of this quantum optical spin glass. This practicable
system could serve as a testbed for exploring how quantum effects enrich the
physics of spin glasses.
