The (2+1)-d U(1) Quantum Link Model Masquerading as Deconfined Criticality

TL;DR

This paper investigates a (2+1)-dimensional U(1) quantum link model that exhibits features similar to deconfined quantum criticality but remains confining at zero temperature, with deconfinement occurring only at high temperatures.

Contribution

It provides a detailed analysis of the low-energy effective field theory of the model and clarifies its relation to deconfined criticality and confinement.

Findings

Model mimics deconfined quantum criticality features

Remains linearly confining at zero temperature

Deconfinement occurs only at high temperature

Abstract

The $(2+1)$-d U(1) quantum link model is a gauge theory, amenable to quantum simulation, with a spontaneously broken SO(2) symmetry emerging at a quantum phase transition. Its low-energy physics is described by a $(2+1)$-d $\RP(1)$ effective field theory, perturbed by a dangerously irrelevant SO(2) breaking operator, which prevents the interpretation of the emergent pseudo-Goldstone boson as a dual photon. At the quantum phase transition, the model mimics some features of deconfined quantum criticality, but remains linearly confining. Deconfinement only sets in at high temperature.