# Quantum Critical States and Phase Transitions in the Presence of Non-Equilibrium Noise

 Title: Quantum Critical States and Phase Transitions in the Presence of Non-Equilibrium Noise Author: Torre, Emanuele; Giamarchi, Thierry; Altman, Ehud; Demler, Eugene A. Note: Order does not necessarily reflect citation order of authors. Citation: Torre, Emanuele, Eugene Demler, Thierry Giamarchi, and Ehud Altman. 2010. Quantum critical states and phase transitions in the presence of non-equilibrium noise. Nature Physics 6(10): 806-810. Full Text & Related Files: 0908.0868v2.pdf (258.2Kb; PDF) Abstract: Quantum critical points are characterized by scale invariant correlations and correspondingly long-ranged entanglement. As such, they present fascinating examples of quantum states of matter, the study of which has been an important theme in modern physics. Nevertheless very little is known about the fate of quantum criticality under non-equilibrium conditions. In this paper we investigate the effect of external noise sources on quantum critical points. It is natural to expect that noise will have a similar effect to finite temperature, destroying the subtle correlations underlying the quantum critical behavior. Surprisingly we find that in many interesting situations the ubiquitous $$1/f$$ noise preserves the critical correlations. The emergent states show intriguing interplay of intrinsic quantum critical and external noise driven fluctuations. We demonstrate this general phenomenon with specific examples in solid state and ultracold atomic systems. Moreover our approach shows that genuine quantum phase transitions can exist even under non equilibrium conditions. Published Version: doi:10.1038/nphys1754 Other Sources: http://arxiv.org/abs/0908.0868 Terms of Use: This article is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#OAP Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:8005349

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