Configuration-interaction Monte Carlo method and its application to the trapped unitary Fermi gas

Abstract

We develop a quantum Monte Carlo method to estimate the ground-state energy of a fermionic many-particle system in the configuration-interaction shell model approach. The fermionic sign problem is circumvented by using a guiding wave function in Fock space. The method provides an upper bound on the ground-state energy whose tightness depends on the choice of the guiding wave function. We argue that the antisymmetric geminal product class of wave functions is a good choice for guiding wave functions. We demonstrate our method for the trapped two-species fermionic cold atom system in the unitary regime of infinite scattering length using the particle-number projected Hartree-Fock-Bogoliubov wave function as the guiding wave function. We estimate the ground-state energy and energy-staggering pairing gap as a function of the number of particles. Our results compare favorably with exact numerical diagonalization results and with previous coordinate-space Monte Carlo calculations.

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Cited by in corpus (10)

• Density matrix quantum Monte Carlo
• Quantum Monte Carlo calculations of neutron matter with non-local chiral interactions
• The sign problem in full configuration interaction quantum Monte Carlo: Linear and sub-linear representation regimes for the exact wave function
• Microscopically constrained mean field models from chiral nuclear thermodynamics
• Constraining the nuclear energy density functional with quantum Monte Carlo calculations
• The pseudogap regime in the unitary Fermi gas
• Predicting Energies of Small Clusters from the Inhomogeneous Unitary Fermi Gas
• Trapped unitary two-component Fermi gases with up to ten particles
• Quantum Monte Carlo in Configuration Space with Three-Nucleon Forces
• Coupled pair approach for strongly-interacting trapped fermionic atoms