Hamiltonian fermion bags is a Quantum Monte Carlo technique I have developed that is especially suited to quantum phase transitions involving fermions that have local interactions. As opposed to the more standard Auxiliary Field Technique, fermion bags involve expansions in the Hamiltonian that allow one to have more of a worldline-based picture in continuous time (inverse temperature). This worldline-based picture then allows one to group fermions into more local segments of space and time (bags), that can speed up computations significantly.
For example, I have studied systems in continuous time (inverse temperature) on lattices containing 64×64 sites, far beyond previous largest sizes of 32×32. This has allowed for the clarification of universality classes for models of relativistic electrons known as Gross-Neveu theories.
Relevant Publications
Quantum Criticality of Antiferromagnetism and Superconductivity with Relativity
Phys. Rev. Lett. 128 (2022)
Fermion-bag inspired Hamiltonian lattice field theory for fermionic quantum criticality
Phys. Rev. D 101, 074501 (2020)
Fermion bag approach to Hamiltonian lattice field theories in continuous time
Phys. Rev. D 96, 114502 (2017)
Solution to sign problems in half-filled spin-polarized electronic systems
Phys. Rev. B 89, 111101(R) (2014)
