title: Luther-Emery phase and atomic-density waves in a trapped fermion gas.
abstract: The Luther-Emery liquid is a state of matter that is predicted to occur in one-dimensional systems of interacting fermions and is characterized by a gapless charge spectrum and a gapped spin spectrum. In this Letter we discuss a realization of the Luther-Emery phase in a trapped cold-atom gas. We study by means of the density-matrix renormalization-group technique a two-component atomic Fermi gas with attractive interactions subject to parabolic trapping inside an optical lattice. We demonstrate how this system exhibits compound phases characterized by the coexistence of spin pairing and atomic-density waves. A smooth crossover occurs with increasing magnitude of the atom-atom attraction to a state in which tightly bound spin-singlet dimers occupy the center of the trap. The existence of atomic-density waves could be detected in the elastic contribution to the light-scattering diffraction pattern.
authors.affiliation: NEST-CNR-INFM and Scuola Normale Superiore, I-56126 Pisa, Italy.
authors.forename: Gao
authors.initials: G
authors.lastname: Xianlong
authors.forename: M
authors.initials: M
authors.lastname: Rizzi
authors.forename: Marco
authors.initials: M
authors.lastname: Polini
authors.forename: Rosario
authors.initials: R
authors.lastname: Fazio
authors.forename: M P
authors.initials: MP
authors.lastname: Tosi
authors.forename: V L
authors.initials: VL
authors.lastname: Campo
authors.forename: K
authors.initials: K
authors.lastname: Capelle