Short-Range Entangled Phases of Fermions

Author: Turzillo, Alexander Michael

Year: 2019

Degree: Dissertation (Ph.D.)

Advisor: Kapustin, Anton N.

Committee Members: Motrunich, Olexei I.; Chen, Xie; Marcolli, Matilde; Kapustin, Anton N.

Option: Physics

DOI: 10.7907/3JR4-8G12

Abstract

This thesis is an attempt to understand the physics of short-range entangled phases of fermions through several related approaches. The first angle is topological quantum field theory. We discuss the classification of interacting fermionic short-range entangled phases by spin cobordism and give an algebraic characterization of unoriented equivariant bosonic topological quantum field theories in one spatial dimension. A second tool is tensor network representation. We develop the formalism of fermionic matrix product states and use it to derive the stacking group law for one dimensional symmetry-enriched fermionic short-range entangled phases. We also study its relationship with state sum constructions of topological quantum field theories and develop a state sum construction for pin-minus theories in one spatial dimension. The third approach is topological band theory. We classify free fermionic phases enriched by a unitary symmetry in any dimension and determine the map into the interacting classification.

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