21 Nov
2019
21 Nov
'19
9:02 a.m.
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.