2,066 research outputs found
Topological Phases of One-Dimensional Fermions: An Entanglement Point of View
The effect of interactions on topological insulators and superconductors
remains, to a large extent, an open problem. Here, we describe a framework for
classifying phases of one-dimensional interacting fermions, focusing on
spinless fermions with time-reversal symmetry and particle number parity
conservation, using concepts of entanglement. In agreement with an example
presented by Fidkowski \emph{et. al.} (Phys. Rev. B 81, 134509 (2010)), we find
that in the presence of interactions there are only eight distinct phases,
which obey a group structure. This is in contrast to the
classification in the non-interacting case. Each of these eight
phases is characterized by a unique set of bulk invariants, related to the
transformation laws of its entanglement (Schmidt) eigenstates under symmetry
operations, and has a characteristic degeneracy of its entanglement levels. If
translational symmetry is present, the number of distinct phases increases to
16.Comment: 12 pages, 1 figure; journal ref. adde
The Role-Based Performance Scale: Validity Analysis of a Theory-Based Measure
This study introduces a theory-based measure of employee performance (Role Based Performance Scale, RBPS) that is supported with results from a validation study using 10 data sets from six companies. In contrast to traditional, job-related measures of employee performance, we propose an alternative measure of performance based on role theory and identity theory. Because our results support the validity of the scale, we think that the instrument can be used for future research that requires a generalizable measure of performance. The scale demonstrates diagnostic properties that make it useful for practitioners as well as researchers
Topological phases in gapped edges of fractionalized systems
Recently, it has been proposed that exotic one-dimensional phases can be
realized by gapping out the edge states of a fractional topological insulator.
The low-energy edge degrees of freedom are described by a chain of coupled
parafermions. We introduce a classification scheme for the phases that can
occur in parafermionic chains. We find that the parafermions support both
topological symmetry fractionalized phases as well as phases in which the
parafermions condense. In the presence of additional symmetries, the phases
form a non-Abelian group. As a concrete example of the classification, we
consider the effective edge model for a fractional topological
insulator for which we calculate the entanglement spectra numerically and show
that all possible predicted phases can be realized.Comment: 11 pages, 7 figures, final versio
Simulating 2+1d Lattice QED with dynamical matter using ultracold atoms
We suggest a method to simulate lattice compact Quantum Electrodynamics
(cQED) using ultracold atoms in optical lattices, which includes dynamical
Dirac fermions in 2+1 dimensions. This allows to test dynamical effects of
confinement as well as 2d flux loops deformations and breaking, and to observe
Wilson-loop area-law.Comment: Includes supplementary material. Added references, minor
modification
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