<i>Ab initio</i> auxiliary-field quantum Monte Carlo study of finite-temperature properties of the two-dimensional Fermi ga

Finite-temperature properties of the two-dimensional unpolarized Fermi gas with a zero-range attractive interaction are studied by a numerically exact auxiliary-field quantum Monte Carlo method [1]. This system has generated strong experimental and theoretical interest as a clean and well-controlled testground for a rich set of physics combining strong interaction and superfluidity in two dimensions. To reliably reach the continuum limit, we adopt a new finite-temperature algorithm [1], which has computational scaling as linear in lattice size instead of cubic as in the standard algorithm. Numerically exact results for the equation of state, contact parameter, momentum distributions as well as pairing properties are obtained across the BCS-BEC crossover, spanning the entire temperature range and connecting with exact zero-temperature results [2]. We also investigate the Berezinskii-Kosterlitz-Thouless transition and possible pseudogap physics in this system.
References:
[1] Yuan-Yao He, Hao Shi, Shiwei Zhang, Physical Review Letters. 123, 136402 (2019).
[2] Hao Shi, Simone Chiesa, Shiwei Zhang, Physical Review A 92, 033603 (2015).