Exact nonequilibrium transport in the topological Kondo effect

TL;DR

This paper provides an exact solution for nonequilibrium transport in the topological Kondo effect, revealing universal conductance behavior and fractional charge quantization, aiding experimental verification of Majorana fermion dynamics.

Contribution

It identifies an anisotropic limit of the topological Kondo problem allowing exact calculations of conductance and noise, offering new insights into topological quantum systems.

Findings

Exact conductance and shot noise calculations in a specific limit.

Universal conductance scaling function near the Kondo fixed point.

Observation of fractional charge quantization via Fano factor.

Abstract

A leading candidate for experimental confirmation of the non-local quantum dynamics of Majorana fermions is the topological Kondo effect, predicted for mesoscopic superconducting islands connected to metallic leads. We identify an anisotropic, Toulouse-like, limit of the topological Kondo problem where the full nonequilibrium conductance and shot noise can be calculated exactly. Near the Kondo fixed point, we find novel asymptotic features including a universal conductance scaling function, and fractional charge quantisation observable via the Fano factor. In the universal regime, our results apply for generic anisotropy and even away from the Kondo limit as long as the system supports an emergent topological Kondo fixed point. Our approach thus provides key new qualitative insights and exact expressions for quantitative comparisons to future experimental data.