Theory Seminar: Quantum East-like models

Nicola Pancotti (MPQ)
In this talk, I will explain in detail the dynamical properties of the quantum East model, an interacting quantum spin chain inspired byain inspired by simple kinetically constrained models of classical glasses.

Nicola Pancotti (MPQ)
MPQ, Herbert-Walther Lecture Hall G0.25
Wed 11. March 2020, 11:30 am

Abstract:

In this talk, I will explain in detail the dynamical properties of the quantum East model, an interacting quantum spin chain inspired by simple kinetically constrained models of classical glasses. I will show the existence of a fast-to-slow transition throughout the spectrum that follows from a localization transition in the ground state. On the slow side, I will explicitly construct a large (exponential in size) number of non-thermal states which become exact finite-energy-density eigenstates in the large size limit, as expected for a true phase transition. Many of these excited states have large overlap with product states and can be approximated well by matrix product states at arbitrary energy densities. I will introduce the super-spin picture which allows to find a further large class of area-law states proved to display very slow relaxation. I will further support these results with extensive numerical analyses and show that the non-thermal features of the model may go far beyond the analytical constructions. Finally, I will show that similar dynamical properties can be found for a much larger class of models and can be extended also to two dimensional systems.