Vison excitations in near-critical quantum dimer models

TL;DR

This paper investigates vison excitations in a quantum dimer model transitioning from a critical square lattice to a Z2 phase, revealing large, vortex-like visons near the critical point.

Contribution

It provides a variational analysis of vison excitations in a near-critical quantum dimer model, highlighting their vortex-like structure and size.

Findings

Visons are large and vortex-like near the critical point.

The model interpolates between critical and Z2 phases.

Vison structure resembles vortices in type-II superconductors.

Abstract

We study vison excitations in a quantum dimer model interpolating between the Rokhsar-Kivelson models on the square and triangular lattices. In the square-lattice case, the model is known to be critical and characterized by U(1) topological quantum numbers. Introducing diagonal dimers brings the model to a Z_2 resonating-valence-bond phase. We study variationally the emergence of vison excitations at low concentration of diagonal dimers, close to the critical point. We find that, in this regime, vison excitations are large in size and their structure resembles vortices in type-II superconductors.