A quasi-two-dimensional dipolar Fermi gas: collective modes, stability and superfluid transition

Full text: We study a single-component dipolar Fermi gas, polarized by an external field and tightly confined in one spatial dimension (quasi-two-dimensional). We find that the excitation spectrum of this system strongly depends on the angle between the polarization direction of the dipoles and the plane of their confinement: Collective modes are absent when the dipoles are aligned perpendicular to the plane. As the dipoles are tilted towards the plane, collective modes appear and their excitation energy eventually becomes imaginary above a certain critical angle, indicating that the filled Fermi sea is not the true ground state of the system any more. In a certain range of values of the tilting angle the ground state of the system appears to be a BCS superfluid. In our calculations of the transition temperature to this phase we go beyond the standard BCS mean-field approach and include many-body effects. (author)