Scaling up a sign-ordered Kitaev chain without magnetic flux control

TL;DR

This paper proposes a practical method to scale up sign-ordered Kitaev chains using electrostatic gates, enhancing Majorana zero mode protection without magnetic flux control, thus aiding topological quantum computing.

Contribution

It introduces a new protocol for extending Kitaev chains with improved protection, relying solely on electrostatic gating instead of magnetic flux control.

Findings

Protocol enables chain scaling with enhanced Majorana protection

Uses electrostatic gates to control hopping signs

Simplifies device design for topological quantum systems

Abstract

Quantum dot-superconductor arrays have emerged as a new and promising material platform for realizing topological Kitaev chains. So far, experiments have implemented a two-site chain with limited protection. Here we propose an experimentally feasible protocol for scaling up the chain in order to enhance the protection of the Majorana zero modes. To this end, we make use of the fact that the relative sign of normal and superconducting hoppings mediated by an Andreev bound state can be changed by electrostatic gates. In this way, our method only relies on the use of individual electrostatic gates on hybrid regions, quantum dots, and tunnel barriers, respectively, without the need for individual magnetic flux control, greatly simplifying the device design. Our work provides guidance for realizing a topologically protected Kitaev chain, which is the building block of error-resilient topological quantum computation.