Speaker: Emilie Huffman (University of Würzburg)
Title: Fermion Bag Algorithms and Sign-Problem-Free Models
Abstract: Quantum Monte Carlo methods, when applicable, offer reliable ways to extract the nonperturbative physics of strongly-correlated many-body systems. However, the sign problem and algorithmic update inefficiencies cause formidable bottlenecks to the applicability of these methods. I demonstrate how the fermion bag approach--originally developed in the context of lattice field theories--has led to novel sign problem solutions for various models containing both fermionic and bosonic degrees of freedom, ranging from Lagrangian lattice field theories to continuous-time Hamiltonian systems, and how fermion bags can be combined with other existing methods such as the meron cluster approach to expand classes of known solvable models. I also show how the idea of fermion bags has led to the development of more efficient QMC algorithms to study such models--specifically through its effectiveness in determining the critical exponents for the chiral Ising universality class involving one flavor of four-component Dirac fermions.