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Duality between the deconfined quantum-critical point and the bosonic topological transition
Time:2017-05-08

Zi Yang Meng, IOP, CAS

时间:Mon,2017-05-15,10:30-11:30

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 strongly-correlated systems: the one relating the easy-plane noncompact CP^1 model (NCCP^1) and noncompact quantum electrodynamics (QED) with two flavors (N = 2) of massless two-component Dirac fermions. The easy-plane NCCP^1 model is the field theory for the putative deconfined quantum-critical point separating a planar (XY) antiferromagnet and a dimerized (valence-bond solid) ground state, while N=2 noncompact QED is the theory for the transition between a bosonic symmetry-protected 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 J-Q spin Hamiltonian (a quantum XY-model model with additional multi-spin couplings) and show that it hosts a continuous transition between the planar magnet and the valence-bound 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. Hae-Young Kee and Prof. Yong-Baek 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 Thousand-Young-Talents 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.

 

 

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