In this talk I will discuss two different projects, unified by the theme of variational methods using “mean-field” type variational states. In the first part, I will introduce a variational manifold of simple tensor network states for the study of constrained spin systems as realized by Rydberg atom arrays. The approach provides a framework to perform the calculations required for variational energy minimization and variational time evolution. We apply this framework to the (generalized) PXP model on 1D, 2D, and 3D hypercubic lattices and show that in each case, it exhibits quantum phase transitions breaking the sublattice symmetry in equilibrium, and hosts quantum many-body scars out of equilibrium. Next, I discuss a variational study of the SU(2) level-k Kogut-Susskind model, which is a modification of the original SU(2) lattice gauge theory that truncates the infinite dimensional local Hilbert space to make it amenable to numerical and quantum simulation, and is also essentially a perturbation of the Levin-Wen string net model. We use a mean-field inspired ansatz that allows efficient analytical calculation of certain quantities and captures key properties of the ground state and low-lying excitations, including the transition between confined and deconfined (topologically ordered) phases. 

报告人简介

现在在Innsbruck大学和奥地利科学院IQOQI（量子光学与量子信息研究所）读博士，在Hannes Pichler 的研究组里。研究方向为量子多体物理，尤其关于tensor networks的应用。本科毕业于牛津大学。

邀请人

石弢 研究员