Entanglement entropy and disorder operator at kagome deconfined quantum criticality

TL;DR

This study uses quantum Monte Carlo simulations to analyze entanglement entropy and disorder operators at a kagome lattice deconfined quantum critical point, revealing unique critical properties consistent with a unitary conformal field theory.

Contribution

It provides the first detailed numerical evidence that the kagome DQCP exhibits positive logarithmic corrections and an enhanced central charge, indicating fractionalized excitations and a genuine deconfined criticality.

Findings

Positive logarithmic correction coefficients consistent with a unitary CFT

Enhanced central charge approximately 4/3 times that of the 3D O(2) Wilson-Fisher fixed point

Presence of two linearly dispersing modes with a velocity ratio of about three

Abstract

We investigate the deconfined quantum critical point (DQCP) candidate in the extended hard-core Bose-Hubbard model on the kagome lattice, employing quantum Monte Carlo simulations to study the entanglement entropy and the $U(1)$ disorder operator. In stark contrast to findings in $J$-$Q$ models and other candidates, the universal logarithmic correction coefficients for both quantities are found to be {positive}, consistent with a unitary conformal field theory (CFT). Crucially, the current central charge $C_J$, extracted from the small-angle behavior of the disorder operator, is enhanced by a factor of approximately {4/3} compared to that of the conventional 3D $O(2)$ Wilson-Fisher fixed point. This enhancement {implies} a consistent explanation in the recently observed low-energy excitation spectrum at this DQCP, which features {two distinct linearly dispersing modes} with a velocity ratio of approximately three. Our results provide evidence that this quantum phase transition constitutes a genuine DQCP, characterized by coexisting fractionalized excitations that collectively modify its critical properties.