Rounding by disorder of first-order quantum phase transitions: emergence of quantum critical points

TL;DR

This paper proposes that disorder can convert first-order quantum phase transitions into continuous ones, supported by analysis of the N-color quantum Ashkin-Teller model in one dimension, revealing a universal behavior similar to the random transverse field Ising model.

Contribution

It introduces a heuristic argument and analysis showing disorder-induced rounding of first-order quantum phase transitions in one-dimensional models, extending understanding of quantum criticality.

Findings

First order transitions are rounded to continuous transitions for N ≥ 3.

The physical behavior aligns with the random transverse field Ising model.

Results differ from classical two-dimensional cases.

Abstract

We give a heuristic argument for disorder rounding of a first order quantum phase transition into a continuous phase transition. From both weak and strong disorder analysis of the the N-color quantum Ashkin-Teller model in one spatial dimension, we find that for $N \geq 3$, the first order transition is rounded to a continuous transition and the physical picture is the same as the random transverse field Ising model for a limited parameter regime. The results are strikingly different from the corresponding classical problem in two dimensions where the fate of the renormalization group flows is a fixed point corresponding to N-decoupled pure Ising models.