IAMS Lecture on Oct. 31, 2:00pm, Poe Lecture Hall, Prof. Guy Cohen
消息來源：原分所
截止日期：2025-10-31
IAMS Lecture Announcement
中研院原分所演講公告
Title: Inchworm Monte Carlo: an Introduction
Speaker: Prof. Guy Cohen (Tel Aviv University, Israel)
Time: 2:00 PM, October 31 (Friday), 2025
Place: Dr. Poe Lecture Hall, IAMS (本所浦大邦講堂臺大校園內)
Contact: Dr. Liang-Yan Hsu 許良彥博士
Abstract:Quantum Monte Carlo (QMC) methods use stochastic integration to solve the many-body problem. They can in principle be applied to a very wide range of physically and chemically important systems. However, because the many-body problem is generally exponentially hard, QMC methods encounter a failure mode known as the “sign problem”: when the system grows, temperature decreases or time increases, the stochastic error increases exponentially. This effectively limits the scope of QMC to applications where the sign problem can be controlled or removed.
The Inchworm technique is a practical way to substantially mitigate sign problems in diagrammatic Monte Carlo methods. It was originally developed for the dynamical sign problem in nonequilibrium quantum impurity models [1], but has since also been applied to multiple expansions for describing dynamics in the spin–boson model [2–4], as well as to multiorbital sign problems encountered in effective equilibrium models used to treat strongly correlated electron materials [5–7]. It can also be formulated directly in the equilibrium or nonequilibrium steady state [8–10]. This talk will include a didactic overview of the technique, followed by a brief discussion of several recent advances and applications.
[1] G. Cohen, E. Gull, D. R. Reichman, and A. J. Millis, Phys. Rev. Lett. 115, 266802 (2015).[2] H.-T. Chen, G. Cohen, and D. R. Reichman, J. Chem. Phys. 146, 054105 (2017).[3] H.-T. Chen, G. Cohen, and D. R. Reichman, J. Chem. Phys. 146, 054106 (2017).[4] O. Goulko, H.-T. Chen, M. Goldstein, and G. Cohen, Phys. Rev. Lett. 134, 056502 (2025).[5] E. Eidelstein, E. Gull, and G. Cohen, Phys. Rev. Lett. 124, 206405 (2020).[6] J. Li, Y. Yu, E. Gull, and G. Cohen, Phys. Rev. B 105, 165133 (2022).[7] D. Goldberger, Y. Fridman, E. Gull, E. Eidelstein, and G. Cohen, Phys. Rev. B 109, 085133 (2024).[8] A. Erpenbeck, E. Gull, and G. Cohen, Phys. Rev. Lett. 130, 186301 (2023).[9] A. Erpenbeck, E. Gull, and G. Cohen, Nano Lett. 23, 10480 (2023).[10] A. Erpenbeck, T. Blommel, L. Zhang, W.-T. Lin, G. Cohen, and E. Gull, The Journal of Chemical Physics 161, 094104 (2024).