title: Many-body characterization of particle-conserving topological superfluids.
abstract: What distinguishes trivial superfluids from topological superfluids in interacting many-body systems where the number of particles is conserved? Building on a class of integrable pairing Hamiltonians, we present a number-conserving, interacting variation of the Kitaev model, the Richardson-Gaudin-Kitaev chain, that remains exactly solvable for periodic and antiperiodic boundary conditions. Our model allows us to identify fermion parity switches that distinctively characterize topological superconductivity (fermion superfluidity) in generic interacting many-body systems. Although the Majorana zero modes in this model have only a power-law confinement, we may still define many-body Majorana operators by tuning the flux to a fermion parity switch. We derive a closed-form expression for an interacting topological invariant and show that the transition away from the topological phase is of third order.
authors.affiliation: Department of Physics, Indiana University, Bloomington, Indiana 47405, USA.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Ortiz
authors.affiliation: Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Dukelsky
authors.affiliation: Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, Netherlands.
authors.forename: Emilio
authors.initials: E
authors.lastname: Cobanera
authors.affiliation: Departamento de Física y Matemáticas, Universidad de Alcala, 28871 Alcala de Henares, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Esebbag
authors.affiliation: Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, Netherlands.
authors.forename: Carlo
authors.initials: C
authors.lastname: Beenakker