Building Hole-Based Andreev Spin Qubits: A Minimal Model Approach from Proximitized Hole Gases

Hybrid semiconductor-superconductor junctions are promising platforms for novel qubits [1], such as the Andreev spin qubit. While realized in III-V semiconductors like InAs, their coherence is limited by strong hyperfine interactions [2]. Arguably, this challenge has motivated a shift toward hybrids based on group IV semiconductors, with germanium emerging as a premier candidate for better hole-based Andreev spin qubits, due to their potential for longer coherence times. In this talk, I will show how our recent theoretical framework for proximitized hole gases [3] offers a versatile starting point for building minimal models of superconducting quantum dots—the fundamental components required to understand this next-generation of hole-based qubits.

[1] Novel qubits in hybrid semiconductor-superconductor nanostructures, Marta Pita-Vidal, Rubén Seoane, Srijit Goswami, Christian Kraglund Andersen, Georgios Katsaros, Javad Shabani,Ramón Aguado, Physics Reports (2025), in preparation.

[2] Coherent manipulation of an Andreev spin qubit, Hays, M. et al. Science 373, 430–433 (2021); Direct manipulation of a superconducting spin qubit strongly coupled to a transmon qubit,Marta Pita-Vidal et al, Nature Physics, 19, 1110 (2023).

[3] Theory of superconducting proximity effect in hole-based hybrid semiconductor-superconductor devices, D Michel Pino, Rubén Seoane-Souto, Maria José Calderón, Ramón Aguado, José Carlos Abadillo-Uriel,Phys. Rev. B 111, 235443, 2025