Fermion condensation and super pivotal categories
Abstract
We study fermionic topological phases using the technique of fermion condensation. We give a prescription for performing fermion condensation in bosonic topological phases which contain a fermion. Our approach to fermion condensation can roughly be understood as coupling the parent bosonic topological phase to a phase of physical fermions, and condensing pairs of physical and emergent fermions. There are two distinct types of objects in fermionic theories, which we call "m-type" and "q-type" particles. The endomorphism algebras of q-type particles are complex Clifford algebras, and they have no analogues in bosonic theories. We construct a fermionic generalization of the tube category, which allows us to compute the quasiparticle excitations in fermionic topological phases. We then prove a series of results relating data in condensed theories to data in their parent theories; for example, if is a modular tensor category containing a fermion, then the tube category of the condensed theory satisfies . We also study how modular transformations, fusion rules, and coherence relations are modified in the fermionic setting, prove a fermionic version of the Verlinde dimension formula, construct a commuting projector lattice Hamiltonian for fermionic theories, and write down a fermionic version of the Turaev-Viro-Barrett-Westbury state sum. A large portion of this work is devoted to three detailed examples of performing fermion condensation to produce fermionic topological phases: we condense fermions in the Ising theory, the theory, and the theory, and compute the quasiparticle excitation spectrum in each of these examples.
Keywords
Cite
@article{arxiv.1709.01941,
title = {Fermion condensation and super pivotal categories},
author = {David Aasen and Ethan Lake and Kevin Walker},
journal= {arXiv preprint arXiv:1709.01941},
year = {2021}
}
Comments
161 pages; v2: corrected typos (including 18 instances of "the the") and added some references