Non-equilibrium $8\pi$ Josephson Effect in Atomic Kitaev Wires

TL;DR

This paper predicts a tunable, non-equilibrium Josephson effect with an unusual 8π periodicity in a Kitaev wire with an extra site, providing a new signature of Majorana particles that can be tested in cold atom experiments.

Contribution

It introduces a minimal model for an 8π Josephson effect in a Kitaev wire with an extra site and confirms its accuracy through numerical simulations, highlighting a novel Majorana signature.

Findings

Identification of an 8π periodic Josephson current in the system

Validation of the minimal model against full numerical solutions

Potential for experimental observation in cold atom setups

Abstract

We theoretically study a Kitaev wire interrupted by an extra site which gives rise to super exchange coupling between two Majorana bound states. We show that this system hosts a tunable, non-equlibrium Josephson effect with a characteristic $8\pi$ periodicity of the Josephson current. We elucidate the physical mechanism deriving a minimal model for the junction and confirm its quantitative accuracy by comparison to the numerical solution of the full model. The visibility of the $8\pi$ periodicity of the Josephson current is then studied using time-dependent simulations including the effects of dephasing and particle losses. Our findings provide a novel signature of Majorana quasi-particles which is qualitatively different form the behavior of a conventional superconductor, and can be experimentally verified in cold atom systems using alkaline-earth-like atoms.