报告人：Prof. Lixin He（Key laboratory of quantum information, University of Science and technology of China）
时间：2018-11-22 15:30-16:30
地点：Room 1114, Sciences Building No. 1
Abstract: The projected entangled pair states (PEPS) methods have been proved to be powerful tools to
solve the strongly correlated quantum many-body problems in two-dimension. However, due to the high
computational scaling with the virtual bond dimension D, PEPS are often limited to rather small bond
dimensions. The optimization of the ground state using imaginary time evolution method with simple
update scheme may go to a larger bond dimension. However, the accuracy of the rough approximation
to the environment of the local tensors is questionable.
We demonstrate that combining the Monte Carlo sampling techniques and gradient optimization offers
an efficient method to calculate the PEPS ground state. By taking the advantages of massive parallel
computing, we can study the quantum systems with larger bond dimensions up to D=16 without resorting
to any symmetry. We apply this method to J1-J2 model. Our results suggest that the ground state in the r
egion of J2 ~0.42 – 0.6 is a gapless spin liquid. We discuss the extension of this method to fermion systems.
个人简历：何力新教授1994年毕业于中国科技大学物理系, 并于1997年获中国科技大学硕士学位。 1998 - 2003年在美国
Rutgers 物理系师从 David Vanderbilt 教授学习第一性原理的计算方法，并获博士学位。2003.9-2006.1在美国国家再生能
源实验室Dr. Alex Zunger 领导的固体理论小组从事半导体量子点的理论研究工作。2006年1月作为国外杰出人才 (百人计
划)引进至中国科技大学中科院量子信息重点实验室工作。 2010年获基金委杰出青年科学基金。2012年入选 IOP fellow
（UK）。2011-2015任科技部量子调控“量子通信网络和量子仿真关键器件的物理实现”项目首席科学家。
