"Qiu Ku" is a chinese word, where Qiu means autumn and Ku stands for a pair of pants. Literally Qiu Ku is a pair of trousers one wears when autumn arrives. In Chinese, Qiu Ku is more than a simple piece of clothing and expresses a nostalgia and sentiment in an affectionate way. In this talk, I will introduce our "Qiu Ku" algorithm, where Qiu Ku is topologically equivalent to a pair of pants and captures the manifold on which the partition function of the computation of entanglement entropy is constructed. To demonstrate its power, the results of few important yet difficult (2+1)d quantum lattice models, ranging from Heisenberg quantum antiferromagnet, quantum critical point with O(3) CFT, deconfined quantum critical point to the toric code Z2 topological order and the Kagome Z2 quantum spin liquid model, will be discussed. 

To request for meeting link, please write to phweb@ust.hk.