HQI Special Seminar

Thursday, November 21
3:00 PM, Jefferson 356

Jeremy Young (UMD), Postdoc Candidate

Driven-dissipative coupled Ising models: a new non-equilibrium universality class

Driven-dissipative systems can potentially exhibit non-equilibrium phenomena that are absent in their equilibrium counterparts. However, phase transitions present in these systems generically exhibit an effectively classical, equilibrium behavior in spite of their non-equilibrium origin. To illustrate this, I will begin by showing how the driven-dissipative Bose-Hubbard model gives rise to emergent thermal behavior near the critical point. I will then investigate an experimentally-motivated model where two Ising-like order parameters interact and form a multicritical point and discuss how at such a multicritical point, new non-equilibrium criticality can emerge. These non-equilibrium multicritical points exhibit a variety of exotic phenomena with no counterpart in equilibrium, including spiraling phase boundaries, the emergence of discrete scale invariance rather than the more familiar continuous scale invariance, and the violation of the fluctuation-dissipation theorem at all length scales, resulting in a sytem which becomes “hotter” and “hotter” at longer and longer wavelengths. Finally, I will discuss some future directions based on these results, such as non-equilibrium quantum criticality.