INCHWORM METHOD FOR OPEN QUANTUM SYSTEMS
数学专题报告
报告题目(Title)：INCHWORM METHOD FOR OPEN QUANTUM SYSTEMS
报告人(Speaker)：SIYAO YANG （University of Chicago）
地点(Place)：后主楼1124
时间(Time)：2024年8月6日14:00-15:00
邀请人(Inviter)：陈华杰
报告摘要
The open quantum systems have shown wide applications including quantum computing, quan- tum chemistry, quantum optics, etc. In an open quantum system, we are interested in the dynamics of a quantum system such as quantum spins or particles coupled with uninteresting environments. In this talk, we introduce a recently proposed algorithm known as inchworm method which has shown its success in simulating open quantum systems. We will start with the Dyson series formulation in which the dynamics of the interesting quantum system can be represented as an infinite sum over thin diagrams, where each thin diagram denotes an integral. As directly summing over these thin diagrams using Monte Carlo may cause large variance, the inchworm method is developed which regroups the thin diagrams into a smaller number of bold diagrams to reduce the variance. We will focus on illustrating how this algorithm can recover the desired dynamics of the quantum system by an iterative calculation of a series of bold diagrams. Further extensions of inchworm method will also be discussed. In particular, we will introduce a combination of inchworm method and frozen Gaussian approximation to simulate a quantum particle coupled with thermal harmonic bath, and another fast diagram-based algorithm developed from inchworm method.
