Novel qubits in hybrid semiconductor–superconductor nanostructures

In recent years, hybrid semiconductor–superconductor qubits have emerged as a compelling alternative to more traditional qubit platforms, owing to their unique combination of material properties and device-level tunability. A key feature of these systems is their gate-tunable Josephson coupling, which enables the realization of superconducting qubit architectures with full electric field control and which offers a promising route toward scalable and low-crosstalk quantum processors. One of the central motivations behind this approach is the possibility of unifying the advantages of superconducting and spin-based qubits. This approach to creating hybrid qubits can be achieved, for example, by encoding quantum information in the spin degree of freedom of a quasiparticle occupying an Andreev bound state, thereby combining long coherence times with fast and flexible control. Recent progress has been further accelerated by the bottom-up engineering of Andreev bound states into coupled quantum dot arrays, leading to the realization of novel device architectures such as minimal Kitaev chains hosting (poor man’s) Majorana states, precursors of topologically protected Majorana zero modes, and, very recently, to the first coherent control of a Majorana parity qubit. In parallel, alternative strategies have focused on the design of Hamiltonian-protected hybrid qubits, including Cooper pair parity qubits and fluxon parity qubits, which aim to enhance robustness against local noise and decoherence. These approaches leverage the interplay between superconducting phase dynamics and the discrete charge or flux degrees of freedom in hybrid junctions. In this article, we review recent theoretical and experimental advances in the development of semiconductor–superconductor hybrid qubits. We provide a comprehensive overview of the underlying physical mechanisms, device implementations, and emerging architectures, with particular emphasis on their potential to enable (topologically) protected quantum information processing. While many of these qubit designs remain at the proof-of-concept stage, the rapid pace of progress suggests that practical demonstrations may be within reach in the near future.