Quantum Information Processing with Hybrid Superconducting Circuits – QIPHSC

Traditional superconducting qubits are based on tunnel Josephson junctions and rely on macroscopic degrees of freedom, namely the superconducting phase difference and the charge difference across the junction. They are therefore intrinsically bosonic by nature. Electronic spin qubits are based on electrons confined in quantum dots and rely on microscopic fermionic degrees of freedom. Here, I propose to engineer a novel elementary quantum object that shares both features. The strategy consists in isolating a unique fermionic degree of freedom from the superconducting condensate in order to form what one could call a "Superconducting Spin Qubit". To achieve this ambitious goal, I propose to perform circuit quantum electrodynamics experiments using hybrid Josephson junctions, in which superconductors are connected through low-dimensional quantum conductors such as carbon nanotubes or semiconducting nanowires. This work will pave the way for the detection of Majorana fermions, elusive quasiparticles that possess a non-abelian quantum statistic.
Beyond the Andreev and Majorana physics on which this project focuses, these hybrid c-QED architectures, which combine quantum conductors and superconducting resonators, provide innovative platforms for studying interesting quantum properties of electronic matter and microwave light. They have huge potential in terms of complexity and control and are promising for quantum information processing and quantum simulation perspectives.