Unconventional triplet pairing state in a polarized dipolar Fermi gas

Vladimir M. Stojanović, W. Vincent Liu, Yong Baek Kim

S. G. Bhongale, Ludwig Mathey, Shan-Wen Tsai +2 more

Y. Endo, Daisuke Inotani, Yoji Ohashi

We present a superfluid theory of a polarized dipolar Fermi gas with an effective dipole-dipole pairing interaction. Treating each dipole as a molecule consisting of two atoms with opposite charges to each other, we show that the well-known ultraviolet divergence in the theory of dipolar Fermi superfluids can be eliminated without introducing any cutoff prescription. Using this cutoff-free superfluid theory, we discuss how the deformation of the Fermi surface coming from the anisotropic nature of the dipole-dipole interaction affects the superfluid order parameter at T = 0.

Randall G. Hulet

Yi Li, Congjun Wu

Ateuafack Mathurin, J. C. Ngana Kuetche, M.N. Jipdi +2 more

Abstract Advances in semiconductor nanostructures have enabled the creation of ultra-cold dipolar fermions, offering a new frontier for exploring many-body fermionic physics. By manipulating electric dipole interactions in these systems, we demonstrate the possibility of cooling and condensing particles. The anisotropic nature of dipole interactions leads to an anisotropic Fermi liquid state, distinct from the isotropic standard, and supports unconventional Cooper pair symmetries involving both singlet and triplet states. Long-range dipolar interactions foster strong correlations within the system. Employing methods such as Gaussian expansion and random-phase-approximation, we analyze how anisotropy influences the spectrum, collective excitations, and correlation functions. In particular, we derive the screened interaction and the polarization function, and we investigate the pairing instability via the Bethe–Salpeter equation in the ladder approximation. The critical temperature for superfluidity is obtained as function of the effective coupling strength. We discuss the the conditions for attractive pairing, the expected order parameter symmetry, and the role of confinement dimensionality. Our results provide a theoretical framework for understanding dipolar Fermi gases in nanostructures and highlight the possibility of realizing unconventional superfluid phases.