Stability of Superflow for Ultracold Fermions in Optical Lattices

Abstract

Motivated by recent observations of superfluidity of ultracold fermions in optical lattices, we investigate the stability of superfluid flow of paired fermions in the lowest band of a strong optical lattice. For fillings close to one fermion per site, we show that superflow breaks down via a dynamical instability leading to a transient density wave. At lower fillings, there is a distinct dynamical instability, where the superfluid stiffness becomes negative; this evolves, with increasing pairing interaction, from the fermion pair breaking instability to the well-known dynamical instability of lattice bosons. Our most interesting finding is the existence of a transition, over a range of fillings close to one fermion per site, from the fermion depairing instability to the density wave instability as the strength of the pairing interaction is increased.

arXiv comment4+ pages, 2 figures

References in corpus (19)

• Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
• How to detect fluctuating order in the high-temperature superconductors
• Probing many-body states of ultra-cold atoms via noise correlations
• Spatial quantum noise interferometry in expanding ultracold atom clouds
• Landau and Dynamical Instabilities of the Superflow of Bose-Einstein Condensates in Optical Lattices
• Evidence for Superfluidity of Ultracold Fermions in an Optical Lattice
• Observation of dynamical instability for a Bose-Einstein condensate in a moving 1D optical lattice
• Quantum Fluctuations in the Superfluid State of the BCS-BEC Crossover
• Collective mode of homogeneous superfluid Fermi gases in the BEC-BCS crossover
• Critical velocity for superfluid flow across the BEC-BCS crossover
• Phase diagram for a Bose-Einstein condensate moving in an optical lattice
• Vortices in Superfluid Fermi Gases through the BEC to BCS Crossover
• Superfluid-insulator transition in a moving system of interacting bosons
• Luther-Emery Phase and Atomic-Density Waves in a Trapped Fermion Gas
• Critical Currents of Ideal Quantum Hall Superfluids
• BEC-BCS crossover in an optical lattice
• Supersolids in confined fermions on one-dimensional optical lattices
• Superfuid-insulator transitions at non-integer filling in optical lattices of fermionic atoms
• Excitations in correlated superfluids near a continuous transition into a supersolid

Cited by in corpus (21)

• Critical velocity of superfluid flow through single barrier and periodic potentials
• Quantum Field Theory for the Three-Body Constrained Lattice Bose Gas -- Part II: Application to the Many-Body Problem
• Collective modes and superflow instabilities of strongly correlated Fermi superfluids
• Critical velocity of flowing supersolids of dipolar Bose gases in optical lattices
• Fermions with attractive interactions on optical lattices and implications for correlated systems
• Instability of superfluid Fermi gases induced by a roton-like density mode in optical lattices
• s-wave Cooper pair insulators and theory of correlated superconductors
• Detecting the superfluid critical momentum of Bose gases in optical lattices through dipole oscillations
• Effects of periodic potentials on the critical velocity of superfluid Fermi gases in the BCS-BEC crossover
• Spatially-modulated Superfluid States in Fermionic Optical Ladder Systems with Repulsive Interactions
• Nonequilibrium dynamics of superconductivity in the attractive Hubbard model
• Superfluidity of Dirac Fermions in a Tunable Honeycomb Lattice: Cooper Pairing, Collective Modes, and Critical Currents
• Multiband superfluidity and superfluid to band-insulator transition of strongly interacting fermions in an optical lattice
• Intervortex forces in competing-order superconductors
• Vortex core order and field-driven phase coexistence in the attractive Hubbard model
• Flow-Induced Charge Modulation in Superfluid Atomic Fermions Loaded into an Optical Kagome Lattice
• Impurity induced phase competition and supersolidity
• Collective excitation and stability of flow-induced gapless Fermi superfluids
• Boosted one dimensional superfluids on a lattice
• Vortex core ordering in Abrikosov lattices
• The attractive Hubbard model as an $SO(3)$ system of competing phases: supersolid order and its thermal melting