Boson-fermion pairing is considered in a discrete environment of bosons and fully spin-polarized fermions, coupled via an attractive Bose-Fermi Hubbard Hamiltonian in one dimension. The results of the $T$ -matrix approximation for particles of equal mass and at double half-filling are compared with the results of exact diagonalization and with quantum Monte Carlo results. Satisfactory agreement for most quantities is found. The appearance of a stable, weak-coupling pairing mode is also confirmed.Boson-fermion pairing is considered in a discrete environment of bosons and fully spin-polarized fermions, coupled via an attractive Bose-Fermi Hubbard Hamiltonian in one dimension. The results of the $T$-matrix approximation for particles of equal mass and at double half-filling are compared with the results of exact diagonalization and with quantum Monte Carlo results. Satisfactory agreement for most quantities is found. The appearance of a stable, weak-coupling pairing mode is also confirmed.

arXiv:0706.2133Physical Review AJan 29, 200831 citations

π Phases in Balanced Fermionic Superfluids on Spin-Dependent Optical Lattices

Ivar Zapata, Bernhard Wünsch, Nikolaj Thomas Zinner +1 more

We study a balanced two-component system of ultracold fermions in one dimension with attractive interactions and subject to a spin-dependent optical lattice potential of opposite sign for the two components. We find states with different types of modulated pairing order parameters which are conceptually similar to π phases discussed for superconductor-ferromagnet heterostructures. Increasing the lattice depth induces sharp transitions between states of different parity. While the origin of the order parameter oscillations is similar to the Fulde-Ferrel-Larkin-Ovchinnikov phase for paired states with spin imbalance, the current system is intrinsically stable to phase separation. We discuss experimental requirements for creating and probing these novel phases.We study a balanced two-component system of ultracold fermions in one dimension with attractive interactions and subject to a spin-dependent optical lattice potential of opposite sign for the two components. We find states with different types of modulated pairing order parameters which are conceptually similar to π phases discussed for superconductor-ferromagnet heterostructures. Increasing the lattice depth induces sharp transitions between states of different parity. While the origin of the order parameter oscillations is similar to the Fulde-Ferrel-Larkin-Ovchinnikov phase for paired states with spin imbalance, the current system is intrinsically stable to phase separation. We discuss experimental requirements for creating and probing these novel phases.

arXiv:0910.1803Physical Review LettersAug 23, 201021 citations

Strongly interacting fermions in a 1D optical lattice

Ariel Sommer, Lawrence W. Cheuk, Mark Ku +3 more

Bulletin of the American Physical SocietyJun 7, 20120 citations

Optimized confinement of fermions in two dimensions

J. D. Cone, Simone Chiesa, V. G. Rousseau +2 more

One of the challenging features of studying model Hamiltonians with cold atoms in optical lattices is the presence of spatial inhomogeneities induced by the confining potential, which results in the coexistence of different phases.This paper presents quantum Monte Carlo results comparing methods for confining fermions in two dimensions, including conventional diagonal confinement, a recently proposed ``off-diagonal confinement'', as well as a trap which produces uniform density in the lattice. At constant entropy and for currently accessible temperatures, we show that (1) diagonal confinement results in the strongest signature of magnetic order, primarily because of its judicious use of entropy sinks at the trap edge and that (2) for d-wave pairing, a trap with uniform density is optimal and can be effectively implemented via off-diagonal confinement. This feature is important to any prospective search for superconductivity in optical lattices.One of the challenging features of studying model Hamiltonians with cold atoms in optical lattices is the presence of spatial inhomogeneities induced by the confining potential, which results in the coexistence of different phases.This paper presents quantum Monte Carlo results comparing methods for confining fermions in two dimensions, including conventional diagonal confinement, a recently proposed ``off-diagonal confinement'', as well as a trap which produces uniform density in the lattice. At constant entropy and for currently accessible temperatures, we show that (1) diagonal confinement results in the strongest signature of magnetic order, primarily because of its judicious use of entropy sinks at the trap edge and that (2) for d-wave pairing, a trap with uniform density is optimal and can be effectively implemented via off-diagonal confinement. This feature is important to any prospective search for superconductivity in optical lattices.

arXiv:1202.0857Physical Review BFeb 21, 20122 citations

Interacting Fermions in Optical Lattices

Tilman Esslinger

Bulletin of the American Physical SocietyMay 19, 20050 citations

T

-matrix approximation for particles of equal mass and at double half-filling are compared with the results of exact diagonalization and with quantum Monte Carlo results. Satisfactory agreement for most quantities is found. The appearance of a stable, weak-coupling pairing mode is also confirmed.