Studying non-equilibrium quasiparticle related errors on superconducting qubits through gap engineering

Non-equilibrium quasiparticles have emerged as a significant source of decoherence in superconducting qubits, prompting a need for effective strategies to mitigate quasiparticle loss. In this study, we delve into innovative chip geometries designed to mitigate non-equilibrium quasiparticle related noise, testing the efficacy of these designs through both non-correlated and correlated charge noise experiments. Additionally, we discuss various fabrication techniques for these chips, informed by microscopic quasiparticle diffusion equations derived from real-time Usadel formalism. This comprehensive approach aims to enhance the performance and reliability of superconducting qubit systems.