Hybrid semiconductor-superconductor quantum dot Josephson junctions for novel qubit applications

During the last few years, hybrid semiconductor-superconductor Josephson junctions are being explored for novel qubit applications [1,2]. In this talk I will focus on semiconducting quantum dot-based Josephson junction and will discuss various examples including: i) quantum dot-based superconducting spin qubits embedded in transmon circuits [3]; ii) the extension of this idea to Josephson junctions based on minimal Kitaev chains to implement a minimal Majorana-Transmon qubit [4]; and (iii) fluxonium qubits which incorporate quantum dot Josephson junctions.

[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] Subgap States in Semiconductor-Superconductor Devices for Quantum Technologies: Andreev Qubits and Minimal Majorana Chains, Rubén Seoane and Ramón Aguado, Chapter 3 in New Trends and Platforms for Quantum Technologies. Lecture Notes in Physics, vol 1025. Springer, Cham (2024). https://doi.org/10.1007/978-3-031-55657-9_3

[3] Direct manipulation of a superconducting spin qubit strongly coupled to a transmon qubit, Marta Pita-Vidal, Arno Bargerbos, Rok Žitko, Lukas J Splitthoff, Lukas Grünhaupt, Jaap J Wesdorp, Yu Liu, Leo P Kouwenhoven, Ramón Aguado, Bernard van Heck, Angela Kou, Christian Kraglund Andersen, Nature Physics, 19, 1110 (2023)

[4] Minimal Kitaev-transmon qubit based on double quantum dots, D Michel Pino, Rubén Seoane Souto, Ramón Aguado, Phys. Rev. B, 109, 075101 (2024)