Bosonization of Majorana modes and edge states

TL;DR

This paper introduces a bosonization method for Majorana modes and edge states, revealing new insights into fermionic edge modes and their relation to lattice geometry and constraints.

Contribution

It develops a bosonization procedure applicable to Majorana modes with specific lattice conditions, connecting to Kitaev's model and exploring boundary phenomena.

Findings

Bosonization requires matching Majorana modes to lattice coordination.

Emergence of fermionic edge modes distinct from topological edge states.

Application to honeycomb, decagonal, rectangular geometries and Hubbard model.

Abstract

We present a bosonization procedure which replaces fermions with generalized spin variables subject to local constraints. It requires that the number of Majorana modes per lattice site matches the coordination number modulo two. If this condition is not obeyed, then bosonization introduces additional fermionic excitations not present in the original model. In the case of one Majorana mode per site on a honeycomb lattice, we recover a sector of Kitaev's model. We discuss also decagonal and rectangular geometries and present bosonization of the Hubbard model. For geometries with a boundary we find that certain fermionic edge modes naturally emerge. They are of different nature than edge modes encountered in topological phases of matter. Euclidean representation for the unconstrained version of a spin system of the type arising in our construction is derived and briefly studied by computing some exact averages for small volumes.