Evidence for Superfluidity of Ultracold Fermions in an Optical Lattice

Abstract

The study of superfluid fermion pairs in a periodic potential has important ramifications for understanding superconductivity in crystalline materials. Using cold atomic gases, various condensed matter models can be studied in a highly controllable environment. Weakly repulsive fermions in an optical lattice could undergo d-wave pairing at low temperatures, a possible mechanism for high temperature superconductivity in the cuprates. The lattice potential could also strongly increase the critical temperature for s-wave superfluidity. Recent experimental advances in the bulk include the observation of fermion pair condensates and high-temperature superfluidity. Experiments with fermions and bosonic bound pairs in optical lattices have been reported, but have not yet addressed superfluid behavior. Here we show that when a condensate of fermionic atom pairs was released from an optical lattice, distinct interference peaks appear, implying long range order, a property of a superfluid. Conceptually, this implies that strong s-wave pairing and superfluidity have now been established in a lattice potential, where the transport of atoms occurs by quantum mechanical tunneling and not by simple propagation. These observations were made for unitarity limited interactions on both sides of a Feshbach resonance. For larger lattice depths, the coherence was lost in a reversible manner, possibly due to a superfluid to insulator transition. Such strongly interacting fermions in an optical lattice can be used to study a new class of Hamiltonians with interband and atom-molecule couplings.

accepted for publication in Nature

References in corpus (8)

• Vortices and Superfluidity in a Strongly Interacting Fermi Gas
• Observation of Bose-Einstein Condensation of Molecules
• Repulsively bound atom pairs in an optical lattice
• Molecules of Fermionic Atoms in an Optical Lattice
• Preparation of a quantum state with one molecule at each site of an optical lattice
• Superfluid Expansion of a Strongly Interacting Fermi Gas
• Multiple species atom source for laser-cooling experiments
• Dressed molecules in an optical lattice

Cited by in corpus (67)

• Theory of ultracold Fermi gases
• Non-Abelian Topological Order in S-Wave Superfluids of Ultracold Fermionic Atoms
• Monte Carlo study of two-dimensional Bose-Hubbard model
• Color Superfluidity and "Baryon" Formation in Ultracold Fermions
• State preparation and dynamics of ultracold atoms in higher lattice orbitals
• Species-specific optical lattices
• Critical velocity for superfluid flow across the BEC-BCS crossover
• Antiferromagnetic Order of Strongly Interacting Fermions in a Trap: Real-Space Dynamical Mean-Field Analysis
• Interaction-controlled transport of an ultracold Fermi gas
• Measuring the one-particle excitations of ultracold fermionic atoms by stimulated Raman spectroscopy
• Finite temperature phase diagram of a polarized Fermi gas in an optical lattice
• Localization-Delocalization Transition of Indirect Excitons in Lateral Electrostatic Lattices
• Superfluidity at the BEC-BCS crossover in two-dimensional Fermi gases with population and mass imbalance
• Level crossing in the three-body problem for strongly interacting fermions in a harmonic trap
• Dynamical mean-field theory and numerical renormalization group study of superconductivity in the attractive Hubbard model
• Superfluid-Insulator Transition of Strongly Interacting Fermi Gases in Optical Lattices
• Berezinskii-Kosterlitz-Thouless transition in trapped quasi-two-dimensional Fermi gas near a Feshbach resonance
• Spectral signatures of the Fulde-Ferrell-Larkin-Ovchinnikov order parameter in one-dimensional optical lattices
• Renormalization group flow for fermionic superfluids at zero temperature
• Luther-Emery Phase and Atomic-Density Waves in a Trapped Fermion Gas
• The effect of population imbalance on the Berezinskii-Kosterlitz-Thouless phase transition in a superfluid Fermi gas
• Superconductivity in the attractive Hubbard model: functional renormalization group analysis
• Light scattering for thermometry of fermionic atoms in an optical lattice
• Supersolid state of ultracold fermions in an optical lattice
• BCS-BEC Crossover of a Quasi-two-dimensional Fermi Gas: the Significance of Dressed Molecules
• Imbalanced Fermi superfluid in a one-dimensional optical potential
• General Hubbard model for strongly interacting fermions in an optical lattice and its phase detection
• Superfluid and insulating phases of fermion mixtures in optical lattices
• Magnetism, coherent many-particle dynamics, and relaxation with ultracold bosons in optical superlattices
• Quantum Hall-like effect for cold atoms in non-Abelian gauge potentials
• Supersolid state in fermionic optical lattice systems
• Supersolids in confined fermions on one-dimensional optical lattices
• Magnetic and superfluid phases of confined fermions in two-dimensional optical lattices
• Characteristics of Bose-Einstein condensation in an optical lattice
• Stability of Superflow for Ultracold Fermions in Optical Lattices
• Molecular Bose-Einstein condensation in a versatile low power crossed dipole trap
• Electron coherent and incoherent pairing instabilities in inhomogeneous bipartite and nonbipartite nanoclusters
• Induced interactions for ultracold Fermi gases in optical lattices
• Effective low-dimensional Hamiltonian for strongly interacting atoms in a transverse trap
• Antiferromagnetic noise correlations in optical lattices
• Population imbalanced fermions in harmonically trapped optical lattices
• Quantum phases of Fermi-Fermi mixtures in optical lattices
• Cold Fermionic Atoms in Two-Dimensional Traps -- Pairing versus Hund's Rule
• Commensurability effects for fermionic atoms trapped in 1D optical lattices
• Noise correlations of the ultra-cold Fermi gas in an optical lattice
• Correlation Effects on Atom Density Profiles of 1-D and 2-D Polarized Atomic-Fermi-Gas Loaded on Optical Lattice
• Spatial patterns in optical lattices submitted to gauge potentials
• Stripe Formation in Fermionic Atoms on 2-D Optical Lattice inside a Box Trap: DMRG Studies for Repulsive Hubbard Model with Open Boundary Condition
• Effects of disorder on atomic density waves and spin-singlet dimers in one-dimensional optical lattices
• Multiband-Driven Superfluid-Insulator Transition of Fermionic Atoms in Optical Lattices: A Dynamical Mean-Field-Theory Study
• Spatially-modulated Superfluid States in Fermionic Optical Ladder Systems with Repulsive Interactions
• Heteronuclear quantum gas mixtures
• Realizing the strongly correlated $d$-Mott state in a fermionic cold atom optical lattice
• Magnetic phases of one-dimensional lattices with 2 to 4 fermions per site
• Tunneling properties of a bound pair of Fermi atoms in an optical lattice
• Superfluidity of fermions with repulsive on-site interaction in an anisotropic optical lattice near a Feshbach resonance
• Interband physics in an ultra-cold Fermi gas in an optical lattice
• Phase diagram of imbalanced fermions in optical lattices
• Magnetism of quantum dot clusters: A Hubbard model study
• Adiabatic cooling of a tunable Bose-Fermi mixture in an optical lattice
• Phase diagram of imbalanced strongly interacting fermions on a one-dimensional optical lattice
• Matter-wave interference in s-wave and p-wave Fermi condensates
• Test of Particle-Assisted Tunneling for Strongly Interacting Fermions in an Optical Superlattice
• Density-Wave and Antiferromagnetic States of Fermionic Atoms in Optical Lattices
• Statistical mechanics of a Feshbach coupled Bose-Fermi gas in an optical lattice
• Flow and critical velocity of an imbalanced Fermi gas through an optical potential
• States of fermionic atoms in an optical superlattice across a Feshbach resonance