Continuum limit results for the unitary Fermi gas and its pseudogap regime*

The unitary Fermi gas (UFG) is a paradigm for strongly correlated Fermi superfluids with applications to dilute neutron matter and can be realized in the lab with ultracold atomic Fermi gases. The existence and extent of a pseudogap regime in the UFG above the critical temperature for superfluidity has been extensively debated in the literature and remains an open question. We present large-scale simulation results in the continuum limit for the condensate fraction and model-independent pairing gaps of the UFG across the superfluid phase transition. The simulations are performed on a discrete lattice using a highly optimized finite-temperature auxiliary-field quantum Monte Carlo (AFMC) algorithm in the canonical ensemble [1]. This extends our previous results for finite filling factor and effective range parameters [2] to the continuum limit. We discuss possible pseudogap signatures in this limit.

[1] C. N. Gilbreth, S. Jensen, and Y. Alhassid, arXiv:1907.10596
[2] S. Jensen, C. N. Gilbreth, and Y. Alhassid, Phys. Rev. Lett. 124, 090604 (2020)