Effects of dissipation on a quantum critical point with disorder

TL;DR

This paper investigates how different types of dissipation influence disordered quantum phase transitions, revealing a non-perturbative infinite-randomness critical point with unique scaling properties under Ohmic damping.

Contribution

It demonstrates that Ohmic dissipation induces an infinite-randomness critical point, contrasting with conventional behavior under superohmic damping, advancing understanding of quantum criticality with disorder and dissipation.

Findings

Ohmic dissipation leads to an infinite-randomness critical point with activated scaling.

Superohmic damping results in conventional critical behavior.

Applications include superconductor-metal transitions and itinerant antiferromagnetic transitions.

Abstract

We study the effects of dissipation on a disordered quantum phase transition with O$(N)$ order parameter symmetry by applying a strong-disorder renormalization group to the Landau-Ginzburg-Wilson field theory of the problem. We find that Ohmic dissipation results in a non-perturbative infinite-randomness critical point with unconventional activated dynamical scaling while superohmic damping leads to conventional behavior. We discuss applications to the superconductor-metal transition in nanowires and to Hertz' theory of the itinerant antiferromagnetic transition.