Emergent Gauge Fields in Band Insulators

TL;DR

This paper demonstrates that certain band insulators with vibrational modes can host a quantum phase featuring emergent gauge fields, gapless photon modes, and deconfined excitations, expanding the understanding of topological phases.

Contribution

It introduces a microscopic construction showing how trivial band insulators can host emergent gauge fields and quantum spin liquid-like states via a mapping to a quantum vertex model.

Findings

Existence of emergent gapless photon modes in the proposed phase

Presence of deconfined excitations with non-quantized charges

Potential realization in nearly ferroelectric materials

Abstract

By explicit microscopic construction involving a mapping to a quantum vertex model subject to the `ice rule,' we show that an electronically `trivial' band insulator with suitable vibrational (phonon) degrees of freedom can host a ``resonating valence-bond'' state - a quantum phase with emergent gauge fields. This novel type of band insulator is identifiable by the existence of emergent gapless `photon' modes and deconfined excitations, the latter of which carry non-quantized mobile charges. We suggest that such phases may exist in the quantum regimes of various nearly ferroelectric materials.