Screw dislocations in the X-cube fracton model

TL;DR

This paper investigates how screw dislocations affect the ground state degeneracy and excitations in the X-cube fracton model, revealing insights into its layered foliation structure and unique fracton dynamics.

Contribution

It demonstrates the impact of screw dislocations on ground state degeneracy and excitations, confirming the foliation structure and uncovering novel fracton behaviors.

Findings

Screw dislocations cause a finite change in the log of ground state degeneracy.

Part of the change is due to layered 2+1D topological states.

Dislocations induce motion of fractons and sub-dimensional excitations.

Abstract

The X-cube model, a prototypical gapped fracton model, has been shown to have a foliation structure. That is, inside the 3+1D model, there are hidden layers of 2+1D gapped topological states. A screw dislocation in a 3+1D lattice can often reveal nontrivial features associated with a layered structure. In this paper, we study the X-cube model on lattices with screw dislocations. In particular, we find that a screw dislocation results in a finite change in the logarithm of the ground state degeneracy of the model. Part of the change can be traced back to the effect of screw dislocations in a simple stack of 2+1D topological states, hence corroborating the foliation structure in the model. The other part of the change comes from the induced motion of fractons or sub-dimensional excitations along the dislocation, a feature absent in the stack of 2+1D layers.