Superfluidity of identical fermions in an optical lattice: atoms and polar molecules

Abstract

In this work, we discuss the emergence of $p$-wave superfluids of identical fermions in 2D lattices. The optical lattice potential manifests itself in an interplay between an increase in the density of states on the Fermi surface and the modification of the fermion-fermion interaction (scattering) amplitude. The density of states is enhanced due to an increase of the effective mass of atoms. In deep lattices, for short-range interacting atoms, the scattering amplitude is strongly reduced compared to free space due to a small overlap of wavefunctions of fermions sitting in the neighboring lattice sites, which suppresses the $p$-wave superfluidity. However, we show that for a moderate lattice depth there is still a possibility to create atomic $p$-wave superfluids with sizable transition temperatures. The situation is drastically different for fermionic polar molecules. Being dressed with a microwave field, they acquire a dipole-dipole attractive tail in the interaction potential. Then, due to a long-range character of the dipole-dipole interaction, the effect of the suppression of the scattering amplitude in 2D lattices is absent. This leads to the emergence of a stable topological $p_x+i{p}_y$ superfluid of identical microwave-dressed polar molecules.

14 pages, 4 figures; prepared for proceedings of the IV International Conference on Quantum Technologies (Moscow, July 12-16, 2017); the present paper summarizes the results of our studies arXiv:1601.03026 and arXiv:1701.08520

References in corpus (21)

• Non-Abelian Anyons and Topological Quantum Computation
• Theory of ultracold Fermi gases
• Vortices and Superfluidity in a Strongly Interacting Fermi Gas
• Evidence for Superfluidity of Ultracold Fermions in an Optical Lattice
• Subwavelength vacuum lattices and atom-atom interactions in photonic crystals
• Cold polar molecules in 2D traps: Tailoring interactions with external fields for novel quantum phases
• Stable Topological Superfluid Phase of Ultracold Polar Fermionic Molecules
• Observation of a two-dimensional Fermi gas of atoms
• Repulsive shield between polar molecules
• Collisional Properties of p-Wave Feshbach Molecules
• Binding Energies of 6Li p-wave Feshbach Molecules
• Majorana modes and $p$-wave superfluids for fermionic atoms in optical lattices
• Nano-Scale `Dark State' Optical Potentials for Cold Atoms
• State-dependent, addressable subwavelength lattices with cold atoms
• Resonant Scattering of Ultracold Atoms in Low Dimensions
• Engineering Superfluidity in Bose-Fermi Mixtures of Ultracold Atoms
• Subwavelength-width optical tunnel junctions for ultracold atoms
• Predicted signatures of p-wave superfluid phases and Majorana zero modes of fermionic atoms in RF absorption
• P-wave superfluidity of atomic lattice fermions
• Generalised Kronig-Penney model for ultracold atomic quantum systems
• Topological quantum phase transitions of ultracold fermions in optical lattices