Special Colloquium

Raahul Nandkishore, Princeton

"Many body localization: a new frontier for quantum statistical physics"

12:30pm, RLM 11.204

Abstract: The existing theory of quantum statistical mechanics describes open systems in contact with large reservoirs. However, experimental advances in the construction and control of isolated quantum systems have highlighted the need for an analogous theory of isolated quantum systems. It has been realized that isolated many body quantum systems can support behavior which has no analog in traditional statistical mechanics. A prominent example is the phenomenon of many body localization. 

Many body localization occurs in isolated quantum systems, usually with strong disorder, and is marked by absence of dissipation, absence of thermal equilibration, and a memory of the initial conditions that survives in local observables for arbitrarily long times. The many body localized regime is a far from equilibrium, strongly disordered regime that constitutes a new frontier for quantum statistical mechanics. Recently, my co-workers and I have demonstrated that many body localization opens the door to new states of matter which cannot exist in thermal equilibrium, such as topologically ordered states without a bulk gap, and broken symmetry states at high energy densities in one dimension. We have also uncovered a host of unexpected properties, such as a set of universal spectral features and a non-local charge response, that have striking implications for fields as diverse as quantum Hall based quantum computation and quantum control. In this talk, I review the essential features of the many body localization phenomenon, and present some of the recent progress that I have made in this field. I also discuss the implications of these results for both theory and experiment, and the connections with diverse areas of theoretical physics. I conclude with a discussion of future directions. 

Reference: Rahul Nandkishore and David A. Huse, arXiv: 1404.0686 [Annual Reviews of Condensed Matter Physics, 2015]