@article { ISI:000571724100001,
title = {A comparison of g((1)) (tau), g((3/2))(tau), and g((2))(tau) for radiation from harmonic oscillators in Brownian motion with a coherent background},
journal = {Phys. Scr.},
volume = {95},
number = {10},
year = {2020},
month = {OCT},
pages = {104001},
publisher = {IOP PUBLISHING LTD},
type = {Article},
abstract = {We compare the field-fieldg((1))(tau), intensity-fieldg((3/2))(tau), and intensity-intensityg((2))(tau) correlation functions for models that are of relevance in astrophysics. We obtain expressions for the general case of a chaotic radiation, where the amplitude is Rician based on a model with an ensemble of harmonic oscillators in Brownian motion. We obtain the signal to noise ratios for two methods of measurement. The intensity-field correlation function signal to noise ratio scales with the first power of vertical bar g((1))(tau). This is in contrast with the well-established result of g((2))(t)((2))(tau) which goes as the square of vertical bar g((1))(tau)vertical bar.},
keywords = {astrophysics, field correlation, intensity correlation, intensity-field correlation, Statistical Physics},
issn = {0031-8949},
doi = {10.1088/1402-4896/abac37},
author = {Siciak, A. and Hugbart, M. and Guerin, W. and Kaiser, R. and Orozco, L. A.}
}
@article { ISI:000515062100001,
title = {Nonequilibrium Fixed Points of Coupled Ising Models},
journal = {Phys. Rev. X},
volume = {10},
number = {1},
year = {2020},
month = {FEB 19},
pages = {011039},
publisher = {AMER PHYSICAL SOC},
type = {Article},
abstract = {Driven-dissipative systems are expected to give rise to nonequilibrium phenomena that are absent in their equilibrium counterparts. However, phase transitions in these systems generically exhibit an effectively classical equilibrium behavior in spite of their nonequilibrium origin. In this paper, we show that multicritical points in such systems lead to a rich and genuinely nonequilibrium behavior. Specifically, we investigate a driven-dissipative model of interacting bosons that possesses 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) Z(2) symmetry. However, they coalesce at a multicritical point, giving rise to a nonequilibrium model of coupled Ising-like order parameters described by a Z(2) x Z(2) symmetry. Using a dynamical renormalization-group approach, we show that a pair of nonequilibrium 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 and spiraling phase boundaries, and it is also accompanied by a complex Liouvillian gap even close to the phase transition. As direct evidence of the nonequilibrium nature of the NEFPs, we show that the fluctuation-dissipation relation is violated at all scales, leading to an effective temperature that becomes {\textquoteleft}{\textquoteleft}hotter{{\textquoteright}{\textquoteright}} and {\textquoteleft}{\textquoteleft}hotter{{\textquoteright}{\textquoteright}} at longer and longer wavelengths. Finally, we argue that this nonequilibrium behavior can be observed in cavity arrays with cross-Kerr nonlinearities.},
keywords = {Photonics, Quantum Physics, Statistical Physics},
issn = {2160-3308},
doi = {10.1103/PhysRevX.10.011039},
author = {Young, Jeremy T. and Gorshkov, Alexey V. and Foss-Feig, Michael and Maghrebi, Mohammad F.}
}