A quantum liquid with deconfined fractional excitations in three dimensions

TL;DR

This paper provides numerical evidence for a three-dimensional quantum liquid phase supporting fractional excitations, demonstrating a Coulomb phase in a quantum dimer model on a diamond lattice.

Contribution

It is the first to explicitly show a 3D quantum liquid with deconfined fractional excitations in a concrete microscopic model.

Findings

Energy cost of separating fractional excitations vanishes in the liquid phase.

Spectrum matches the Coulomb phase in (3+1)D quantum electrodynamics.

Supports the existence of fractional excitations in three dimensions.

Abstract

Excitations which carry "fractional" quantum numbers are known to exist in one dimension in polyacetylene, and in two dimensions, in the fractional quantum Hall effect. Fractional excitations have also been invoked to explain the breakdown of the conventional theory of metals in a wide range of three-dimensional materials. However the existence of fractional excitations in three dimensions remains highly controversial. In this Letter we report direct numerical evidence for the existence of a quantum liquid phase supporting fractional excitations in a concrete, three-dimensional microscopic model - the quantum dimer model on a diamond lattice. We demonstrate explicitly that the energy cost of separating fractional monomer excitations vanishes in this liquid phase, and that its energy spectrum matches that of the Coulomb phase in (3+1) dimensional quantum electrodynamics.