Time Reversal Symmetry Breaking in Driven Dissipative Spin Systems

Time-reversal symmetry is an intrinsic property of equilibrium systems that forbids currents under equilibrium conditions. On the other hand, time-reversal symmetry is explicitly broken in driven systems, leading to new states of matter. In this talk, I discuss the impact of time-reversal symmetry breaking on driven-dissipative systems. I will focus on the driven-dissipative Ising model, and show that a kind of spin current emerges in the non-equilibrium steady state. Interestingly, this current diverges at the critical point and shows nontrivial critical scaling with system size. While previous studies have concluded an effective equilibrium behavior at criticality, we find that the effective temperatures corresponding to two (longitudinal) components of the spin are equal in magnitude but opposite in sign, signaling the extreme non-equilibrium nature of the steady state. Finally, at the weakly dissipative critical point the current remains critical but exhibits new critical scaling. These features are immediately accessible in experimental platforms.