Duality between the deconfined quantumcritical point and the bosonic topological transition 
Time：20170508 
Zi Yang Meng, IOP, CAS 时间：Mon,20170515,10:3011:30 地点：Room 616,Physics Building Abstract: Recently significant progress has been made in (2+1)dimensional conformal field theories without supersymmetry. In particular, it was realized that different field theory Lagrangians may be related by hidden dualities, i.e., seemingly different Lagrangians may actually be identical in the infrared limit. Among all the proposed dualities, one is particularly relevant in the field of stronglycorrelated systems: the one relating the easyplane noncompact CP^1 model (NCCP^1) and noncompact quantum electrodynamics (QED) with two flavors (N = 2) of massless twocomponent Dirac fermions. The easyplane NCCP^1 model is the field theory for the putative deconfined quantumcritical point separating a planar (XY) antiferromagnet and a dimerized (valencebond solid) ground state, while N=2 noncompact QED is the theory for the transition between a bosonic symmetryprotected topological phase and a trivial Mott insulator. In this work we present strong numerical support for the proposed duality. We realize the N=2 noncompact QED at a critical point of an interacting fermion model on the bilayer honeycomb lattice and study it using determinant quantum Monte Carlo (QMC) simulations. Also, using stochastic series expansion QMC, we study a planer version of the S=1/2 JQ spin Hamiltonian (a quantum XYmodel model with additional multispin couplings) and show that it hosts a continuous transition between the planar magnet and the valencebound solid. The critical exponents extracted from these two models are in good agreement with the prediction based on the proposed duality.
Biography: Dr. Meng got his B.S. in Physics from the University of Science and Technology of China in 2005 and Ph.D. in theoretical condensed matter physics from the University of Stuttgart, Germany, in 2011. He worked as a postdoctoral fellow at the Department of Physics, University of Toronto in the group of Prof. HaeYoung Kee and Prof. YongBaek Kim, and the Department of Physics and Astronomy, Louisiana State University in the group of Prof. Mark Jarrell. He joined the Institute of Physics, Chinese Academy of Sciences (IOP, CAS) as an associate professor in August 2014, with the support from the National ThousandYoungTalents Program of China. His research specializes in strongly correlated electron systems and computational condensed matter physics, in particular quantum Monte Carlo and cluster dynamic mean field simulations.
