Theory seminar: Quantum East-like models

Nicola Pacotti (MPQ)
Wednesday, 11. March 2020, 11:30 am
Herbert-Walther Lecture Hall (G 0.25), MPQ

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.