Properties of the density-wave phase of a two-dimensional dipolar Fermi gas

TL;DR

This paper studies the properties of a density-wave phase in a two-dimensional dipolar Fermi gas at zero temperature, revealing its quasiparticle spectrum, signatures in momentum space, and experimental realization prospects.

Contribution

It provides a detailed theoretical analysis of the density-wave phase in 2D dipolar Fermi gases using Hartree-Fock theory, including spectral and experimental signatures.

Findings

Density-waves induce a 1D Brillouin zone structure.

The quasiparticle spectrum has both gapped and gapless regions.

The phase remains compressible and collapses under strong attraction.

Abstract

The rapid progress in the production and cooling of molecular gases indicates that experimental studies of quantum gases with a strong dipolar interaction is soon within reach. Dipolar gases are predicted to exhibit very rich physics including quantum liquid crystal phases such as density-waves as well as superfluid phases, both of which play an important role for our understanding of strongly correlated systems. Here, we investigate the zero temperature properties of the density-wave phase of a two-dimensional (2D) system of fermonic dipoles using a conserving Hartree-Fock theory. We calculate the amplitude of the density waves as a function of the dipole moment and orientation with respect to the 2D plane. The stripes give rise to a 1D Brillouin zone structure, and the corresponding quasiparticle spectrum is shown to have gapped as well as gapless regions around the Fermi surface. As a result, the system remains compressible in the density-wave phase, and it collapses for strong attraction. We show that the density-waves has clear signatures in the momentum distribution and in the momentum correlations. Both can be measured in time-of-flight experiments. Finally, we discuss how the striped phase can be realised with experimentally available systems.