Dynamical conductivity at the dirty superconductor-metal quantum phase transition

TL;DR

This paper investigates the transport properties near the superconductor-metal quantum phase transition in disordered nanowires, revealing a diverging quantum critical conductivity and activated scaling behavior, with implications for experimental observations.

Contribution

It combines numerical and analytical methods to analyze the quantum critical conductivity and extends scaling theory to higher dimensions.

Findings

Quantum critical conductivity diverges logarithmically at zero temperature.

In the metallic phase, conductivity follows activated scaling.

Results have implications for experimental detection of quantum phase transitions.

Abstract

We study the transport properties of ultrathin disordered nanowires in the neighborhood of the superconductor-metal quantum phase transition. To this end we combine numerical calculations with analytical strong-disorder renormalization group results. The quantum critical conductivity at zero temperature diverges logarithmically as a function of frequency. In the metallic phase, it obeys activated scaling associated with an infinite-randomness quantum critical point. We extend the scaling theory to higher dimensions and discuss implications for experiments.