Monte Carlo simulations of the disordered three-color quantum Ashkin-Teller chain

TL;DR

This study uses large-scale Monte Carlo simulations to explore how quenched disorder affects quantum phase transitions in the disordered three-color quantum Ashkin-Teller chain, revealing emergent critical points and complex behaviors.

Contribution

It provides the first detailed numerical analysis of disorder effects on the quantum Ashkin-Teller chain, confirming predictions of infinite-randomness critical points and exploring new regimes of critical behavior.

Findings

Disorder rounds first-order transitions in the clean system.

Emergent quantum critical point is of infinite-randomness type.

Evidence of unconventional critical behavior at strong inter-color coupling.

Abstract

We investigate the zero-temperature quantum phase transitions of the disordered three-color quantum Ashkin-Teller spin chain by means of large-scale Monte Carlo simulations. We find that the first-order phase transitions of the clean system are rounded by the quenched disorder. For weak inter-color coupling, the resulting emergent quantum critical point between the paramagnetic phase and the magnetically ordered Baxter phase is of infinite-randomness type and belongs to the universality class of the random transverse-field Ising model, as predicted by recent strong-disorder renormalization group calculations. We also find evidence for unconventional critical behavior in the case of strong inter-color coupling, even though an unequivocal determination of the universality class is beyond our numerical capabilities. We compare our results to earlier simulations, and we discuss implications for the classification of phase transitions in the presence of disorder.