Dissipation effects in percolating quantum Ising magnets

TL;DR

This paper investigates how dissipation influences the quantum phase transition in a diluted transverse-field Ising magnet near percolation threshold, revealing a novel transition driven by large frozen clusters.

Contribution

It introduces a new understanding of dissipation effects on percolation quantum phase transitions using a strong-disorder renormalization group approach.

Findings

Identification of a novel percolation quantum phase transition

Agreement of numerical density of states with analytical predictions

Dominance of large frozen clusters near the transition

Abstract

We study the effects of dissipation on a randomly dilute transverse-field Ising magnet at and close to the percolation threshold. For weak transverse fields, a novel percolation quantum phase transition separates a super-paramagnetic cluster phase from an inhomogeneously ordered ferromagnetic phase. The properties of this transition are dominated by large frozen and slowly fluctuating percolation clusters. Implementing numerically a strong-disorder real space renormalization group technique, we compute the low-energy density of states which is found to be in good agreement with the analytical prediction.