Title: Entanglement and Quantum Phase Transition

　　Speaker: Prof. Haiqing Lin（Department Chairman, Department of Physics and the Institute of Theoretical Physics, The Chinese University of Hong Kong, Hong Kong, China）

　　Time: 15:00, Apr. 15, 2010

　　Venue: Academic Salon, Institute of Semiconductors, CAS

　　Abstract: Explore quantities which connect quantum phase transition (QPT) and entanglement are issues of current interest. In this talk, I report our group’s efforts in searching such quantities by studying several well known quantum many-body systems such as the extended Hubbard model and quantum spin models. First we introduce a few computable quantities one can use to measure the entanglement. Then we present our results of model studies. We show some general features of entanglement which signify QPT and argue the important role played by the low-lying excitation spectra reconstruction near the QPT in identifying the behavior of the entanglement. It is hoped that a unified and intuitive picture on the relation between the QPT and the entanglement could be given. We also discuss connection to physical measurement of entanglement..