Novel qubits in hybrid semiconductor-superconductor nanostructures

TL;DR

Hybrid semiconductor-superconductor qubits leverage gate-tunable Josephson coupling and Andreev states, offering a promising route for scalable, low-crosstalk quantum processors with potential topological protection.

Contribution

This review summarizes recent theoretical and experimental advances in hybrid qubits, highlighting new physical mechanisms, device implementations, and architectures for quantum information processing.

Findings

Progress in engineering Andreev states in quantum dot arrays.

Development of architectures hosting Majorana zero modes.

Emerging designs aiming for topologically protected quantum states.

Abstract

Hybrid semiconductor-superconductor qubits have recently emerged as a promising alternative to traditional platforms, combining material advantages with device-level tunability. A defining feature is their gate-tunable Josephson coupling, enabling superconducting qubit architectures with full electric-field control and offering a path toward scalable, low-crosstalk quantum processors. This approach seeks to merge benefits of superconducting and semiconductor qubits, for instance by encoding quantum information in the spin of a quasiparticle occupying an Andreev bound state, thus combining long coherence times with fast, flexible control. Progress has accelerated through bottom-up engineering of Andreev states in coupled quantum dot arrays, leading to architectures such as minimal Kitaev chains hosting Majorana zero modes. In parallel, Hamiltonian-protected designs aim to enhance resilience against local noise and decoherence by exploiting superconducting phase dynamics and discrete charge or flux degrees of freedom. This article reviews recent theoretical and experimental advances in hybrid qubits, providing an overview of physical mechanisms, device implementations, and emerging architectures, with emphasis on their potential for (topologically) protected quantum information processing. While many designs remain at proof-of-concept stage, rapid progress suggests practical demonstrations may soon be achievable.