Heteroatomic Andreev molecule in a superconducting island-double quantum dot hybrid

TL;DR

This paper demonstrates a heteroatomic Andreev molecule composed of quantum dots coupled via a superconducting island, revealing tunable quantum phase transitions and strong electron hybridization, advancing the engineering of topological superconducting materials.

Contribution

It introduces a heteroatomic Andreev molecule with tunable quantum states, providing a new platform for topological superconductor research.

Findings

Strong hybridization of quantum dots forming a molecular state

Quantitative explanation of electron binding via DMRG calculations

Electrical gating enables quantum phase transition between magnetic states

Abstract

Topological superconductors (SCs) hold great promise for fault-tolerant quantum hardware, however, their experimental realization is very challenging. Recently, superconducting artificial molecules (Andreev molecules) have opened new avenues to engineer topological superconducting materials. In this work, we demonstrate a heteroatomic Andreev molecule, where two normal artificial atoms realized by quantum dots (QDs) are coupled by a superconducting island (SCI). We show that the two normal atoms strongly hybridize and form a 3-electron-based molecular state. Our density matrix renormalization group (DMRG) calculations explain quantitatively the robust binding of electrons. The tunability of the structure allows us to drive a quantum phase transition from an antiferromagnetic Andreev molecular state to a heteroatomic Andreev molecule with ferromagnetically coupled QDs using simple electrical gating.