Cavity-renormalized quantum criticality in a honeycomb bilayer antiferromagnet

TL;DR

This study explores how coupling a quantum critical antiferromagnet to an optical cavity enhances critical fluctuations without altering the universality class, using quantum Monte Carlo simulations and realistic parameters.

Contribution

It demonstrates that cavity coupling amplifies critical fluctuations in a quantum antiferromagnet, revealing a fractional scaling exponent and suggesting potential experimental observability.

Findings

Critical fluctuations are enhanced by cavity coupling.

The universality class remains unchanged.

Scaling exponents deviate from simple perturbation theory.

Abstract

Strong light-matter interactions as realized in an optical cavity provide a tantalizing opportunity to control the properties of condensed matter systems. Inspired by experimental advances in cavity quantum electrodynamics and the fabrication and control of two-dimensional magnets, we investigate the fate of a quantum critical antiferromagnet coupled to an optical cavity field. Using unbiased quantum Monte Carlo simulations, we compute the scaling behavior of the magnetic structure factor and other observables. While the position and universality class are not changed by a single cavity mode, the critical fluctuations themselves obtain a sizable enhancement, scaling with a fractional exponent that defies expectations based on simple perturbation theory. The scaling exponent can be understood using a generic scaling argument, based on which we predict that the effect may be even stronger in other universality classes. Our microscopic model is based on realistic parameters for two-dimensional magnetic quantum materials and the effect may be within the range of experimental detection.