Minimal quantum dot based Kitaev chain with only local superconducting proximity effect

TL;DR

This paper proposes a simplified method to engineer a topological Kitaev chain using only local superconducting proximity effects on quantum dots, avoiding complex experimental setups.

Contribution

It introduces a minimal quantum dot setup that achieves topological superconductivity with local effects, eliminating the need for complex couplers or magnetic field variations.

Findings

High-quality Majorana bound states can be generated in a double quantum dot.

The approach simplifies experimental realization of topological superconductivity.

Control of superconducting phase tunes the system into the topological regime.

Abstract

The possibility to engineer a Kitaev chain in quantum dots coupled via superconductors has recently emerged as a promising path toward topological superconductivity and possibly nonabelian physics. Here, we show that it is possible to avoid some of the main experimental hurdles on this path by using only local proximity effect on each quantum dot in a geometry that resembles a two-dot version of the proposal in New J. Phys. 15 045020 (2013). There is no need for narrow superconducting couplers, additional Andreev bound states, or spatially varying magnetic fields; it suffices with spin-orbit interaction and a constant magnetic field, in combination with control of the superconducting phase to tune the relative strengths of elastic cotunneling and an effective crossed-Andreev-reflection-like process generated by higher-order tunneling. We use a realistic spinful, interacting model and show that high-quality Majorana bound states can be generated already in a double quantum dot.