Pair condensation in a Finite Trapped Fermi Gas

Abstract

Superfluidity in the cold atomic two-species Fermi gas system in the unitary limit of infinite scattering length remains incompletely understood. In particular, a pseudogap phase has been proposed to exist above the superfluid critical temperature. Here we apply the auxiliary-field quantum Monte Carlo method to perform the first ab initio calculations of the temperature dependence of three quantities -- the energy-staggering pairing gap, the condensate fraction and the heat capacity -- in a trapped finite-size cold atom system. As the calculations of the energy-staggering pairing gap require the use of the canonical ensemble, we employ a novel algorithm for the stabilization of particle-number projection that is essential for reaching convergence in the size of the model space. We observe clear signatures of the superfluid phase transition in all three quantities, including a signature of the recently measured lambda peak in the heat capacity, but find no evidence of a pseudogap effect in the energy-staggering pairing gap.

5 pages, 1 figure. Added detail on stabilization method

References in corpus (14)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Revealing the Superfluid Lambda Transition in the Universal Thermodynamics of a Unitary Fermi Gas
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Strongly paired fermions: Cold atoms and neutron matter
• Local Density Functional Theory for Superfluid Fermionic Systems: The Unitary Gas
• Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas
• Universal properties of a trapped two-component Fermi gas at unitarity
• Resonantly Interacting Fermions In a Box
• Heavy deformed nuclei in the shell model Monte Carlo method
• The axial anomaly and the phases of dense QCD
• Shell-Model Monte Carlo Simulations of BCS-BEC Crossover in Few-Fermion Systems
• Universal Bound States of Two Particles in Mixed Dimensions or Near a Mirror

Cited by in corpus (10)

• Pairing of few Fermi atoms in one dimension
• Finite Temperature Auxiliary Field Quantum Monte Carlo in the Canonical Ensemble
• The contact in the unitary Fermi gas across the superfluid phase transition
• Pairing correlations across the superfluid phase transition in the unitary Fermi gas
• Emergence of a pseudogap in the BCS-BEC crossover
• The pseudogap regime in the unitary Fermi gas
• Calculating ground state properties of correlated fermionic systems with BCS trial wave functions in Slater determinant path-integral approaches
• Stabilizing Canonical-Ensemble Calculations in the Auxiliary-Field Monte Carlo Method
• A Stable, Recursive Auxiliary Field Quantum Monte Carlo Algorithm in the Canonical Ensemble: Applications to Thermometry and the Hubbard Model
• Structure Factors of The Unitary Gas Under Supernova Conditions