title: Momentum-space entanglement spectrum of bosons and fermions with interactions.
abstract: We study the momentum space entanglement spectra of bosonic and fermionic formulations of the spin-1/2 XXZ chain with analytical methods and exact diagonalization. We investigate the behavior of the entanglement gaps, present in both formulations, across quantum phase transitions in the XXZ chain. In both cases, finite size scaling suggests that the entanglement gap closure does not occur at the physical transition points. For bosons, we find that the entanglement gap observed in Thomale et al. [Phys. Rev. Lett. 105, 116805 (2010)] depends on the scaling dimension of the conformal field theory as varied by the XXZ anisotropy. For fermions, the infinite entanglement gap present at the XX point persists well past the phase transition at the Heisenberg point. We elaborate on how these shifted transition points in the entanglement spectra may support the numerical study of phase transitions in the momentum space density matrix renormalization group.
authors.affiliation: Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Rex
authors.initials: R
authors.lastname: Lundgren
authors.affiliation: Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Blair
authors.affiliation: Insitute for Theoritical Physics, Univesity of Würzburg, D-97074 Würzburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Greiter
authors.affiliation: Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Läuchli
authors.affiliation: Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Fiete
authors.affiliation: Insitute for Theoritical Physics, Univesity of Würzburg, D-97074 Würzburg, Germany.
authors.forename: Ronny
authors.initials: R
authors.lastname: Thomale