Deconfined Quantum Phase Transition of a Higher-Order Symmetry-Protected Topological State

TL;DR

This paper demonstrates a direct topological quantum phase transition from a higher-order symmetry-protected topological state to a trivial phase, revealing a duality between topological transitions and deconfined quantum critical points.

Contribution

It introduces a field-theoretic and quantum Monte Carlo analysis showing the connection between higher-order SPT phases and deconfined quantum criticality, a novel insight into topological phase transitions.

Findings

Topological transition occurs via a deconfined quantum critical point.

The DQCP acts as a multicritical point linking AF-VBS and topological transitions.

The work reveals a duality between SPT topological transitions and DQCPs.

Abstract

A higher-order (HO) symmetry-protected topological (SPT) state can be realized in a plaquette-modulated square lattice antiferromagnet, which hosts a spin-$1/2$ degenerate mode on each corner of the lattice with open boundaries. In this work, we show with the field-theoretic analysis and quantum Monte Carlo simulations that the plaquette modulation can drive a direct topological quantum phase transition from the HOSPT to a trivial disordered phase across the deconfined quantum critical point (DQCP) between the antiferromagnetic (AF) order and the valence bond solid (VBS) order, thus the DQCP is a multicritical point bridging both the AF-VBS transition and the topological transition of the HOSPT phase. Our work thus reveals the ubiquitous duality between topological transitions of SPT phases and DQCPs.