Response functions for the two-dimensional ultracold Fermi gas: dynamical BCS theory and beyond

Abstract

Response functions are central objects in physics. They provide crucial information about the behavior of physical systems, and they can be directly compared with scattering experiments involving particles like neutrons, or photons. Calculations of such functions starting from the many-body Hamiltonian of a physical system are challenging, and extremely valuable. In this paper we focus on the two-dimensional (2D) ultracold Fermi atomic gas which has been realized experimentally. We present an application of the dynamical BCS theory to obtain response functions for different regimes of interaction strengths in the 2D gas with zero-range attractive interaction. We also discuss auxiliary-field quantum Monte Carlo (AFQMC) methods for the calculation of imaginary-time correlations in these dilute Fermi gas systems. Illustrative results are given and comparisons are made between AFQMC and dynamical BCS theory results to assess the accuracy of the latter.

16 pages, 4 figures

References in corpus (7)

• The electronic properties of graphene
• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Observation of pair condensation in the quasi-2D BEC-BCS crossover
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Cited by in corpus (5)

• Visualizing the BEC-BCS crossover in the two-dimensional Fermi gas: pairing gaps and dynamical response functions from ab initio computations
• Variational and Parquet-diagram theory for strongly correlated normal and superfluid systems
• Variational and parquet-diagram calculations for neutron matter. III. S-wave pairing
• An analysis of variational wave function for the pairing problem in strongly correlated system
• Dynamical BCS theory of a two-dimensional attractive Fermi gas: effective interactions from Quantum Monte Carlo calculations