Robust poor man’s Majorana zero modes using Yu-Shiba-Rusinov states

Abstract

Kitaev chains in quantum dot-superconductor arrays are a promising platform for the realization of topological superconductivity. As recently demonstrated, even a two-site chain can host Majorana zero modes known as “poor man’s Majorana”. Harnessing the potential of these states for quantum information processing, however, requires increasing their robustness to external perturbations. Here, we form a two-site Kitaev chain using Yu-Shiba-Rusinov states in proximitized quantum dots. By deterministically tuning the hybridization between the quantum dots and the superconductor, we observe poor man’s Majorana states with a gap larger than 70 μeV. The sensitivity to charge fluctuations is also greatly reduced compared to Kitaev chains made with non-proximitized dots. The systematic control and improved energy scales of poor man’s Majorana states realized with Yu-Shiba-Rusinov states will benefit the realization of longer Kitaev chains, parity qubits, and the demonstration of non-Abelian physics.

A Kitaev chain formed by two quantum dots coupled via a superconductor support the so-called poor man’s Majorana bound states. Here, the authors form a minimal Kitaev chain using Yu-Shiba-Rusinov states and show that the resulting bound states are more robust than in the case of unproximitized quantum dots.