Protocol for scaling up a sign-ordered Kitaev chain without magnetic flux control

Quantum dot-superconductor arrays have emerged as a new and promising material platform for realizing Kitaev chains with Majorana zero modes. So far, experiments have implemented a two-site chain with limited protection. We propose a protocol for scaling up the Kitaev chain that is accessible to current experiments and optimizes the Majorana protection. 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.
Comment: 7+2 pages, 4+2 figures