



@article {2363,
	title = {Non-equilibrium fixed points of coupled Ising models},
	journal = {Phys. Rev. X },
	volume = {10},
	year = {2020},
	month = {2/26/2020},
	abstract = {<p>Driven-dissipative systems can 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 quantum non-equilibrium origin. In this paper, we show that multicritical points in driven-dissipative systems can give rise to genuinely non-equilibrium behavior. We investigate a non-equilibrium driven-dissipative model of interacting bosons that exhibits two distinct phase transitions: one from a high- to a low-density phase---reminiscent of a liquid-gas transition---and another to an antiferromagnetic phase. Each phase transition is described by the Ising universality class characterized by an (emergent or microscopic) Z2 symmetry. They, however, coalesce at a multicritical point giving rise to a non-equilibrium model of coupled Ising-like order parameters described by a Z2\&times;Z2 symmetry. Using a dynamical renormalization-group approach, we show that a pair of non-equilibrium fixed points (NEFPs) emerge that govern the long-distance critical behavior of the system. We elucidate various exotic features of these NEFPs. In particular, we show that a generic continuous scale invariance at criticality is reduced to a discrete scale invariance. This further results in complex-valued critical exponents, spiraling phase boundaries, and a complex Liouvillian gap even close to the phase transition. As direct evidence of the non-equilibrium nature of the NEFPs, we show that the fluctuation-dissipation relation is violated at all scales, leading to an effective temperature that becomes \&quot;hotter\&quot; and \&quot;hotter\&quot; at longer and longer wavelengths. Finally, we argue that this non-equilibrium behavior can be observed in cavity arrays with cross-Kerr nonlinearities.</p>},
	doi = {https://doi.org/10.1103/PhysRevX.10.011039},
	url = {https://arxiv.org/abs/1903.02569},
	author = {Jeremy T. Young and Alexey V. Gorshkov and Michael Foss-Feig and Mohammad F. Maghrebi}
}
@article {2460,
	title = {Nondestructive cooling of an atomic quantum register via state-insensitive Rydberg interactions},
	year = {2019},
	month = {7/28/2019},
	abstract = {<p>We propose a protocol for sympathetically cooling neutral atoms without destroying the quantum information stored in their internal states. This is achieved by designing state-insensitive Rydberg interactions between the data-carrying atoms and cold auxiliary atoms. The resulting interactions give rise to an effective phonon coupling, which leads to the transfer of heat from the data atoms to the auxiliary atoms, where the latter can be cooled by conventional methods. This can be used to extend the lifetime of quantum storage based on neutral atoms and can have applications for long quantum computations. The protocol can also be modified to realize state-insensitive interactions between the data and the auxiliary atoms but tunable and non-trivial interactions among the data atoms, allowing one to simultaneously cool and simulate a quantum spin-model.\&nbsp;</p>},
	url = {https://arxiv.org/abs/1907.11156},
	author = {Ron Belyansky and Jeremy T. Young and Przemyslaw Bienias and Zachary Eldredge and Adam M. Kaufman and Peter Zoller and Alexey V. Gorshkov}
}
