Geometric and thermal effect on non-equilibrium quasiparticles in superconducting qubit

Non-equilibrium quasiparticles are a source of decoherence and instability for superconducting qubits, a potential threat to fault-tolerant quantum computing. In this work, we investigate how they are affected by circuit geometry and temperature with revisited charge qubits. We observe state-of-the-art quasiparticle tunneling rate (less than 1Hz) which is associated with radiation loss from the qubit antenna mode. We also found that thermally activated quasiparticles can be explained by difference in thin film thickness.