Detection of non-equilibrium quasiparticles in charge sensitive transmons

Abstract

Non-equilibrium quasiparticles are considered possible sources causing decoherence in superconducting qubits. Thus, exploring the dynamics of quasiparticles is crucial to understand their mechanism and how to minimize their presence in superconductors. Here, we study charge parity fluctuations in 2D transmon qubits with sufficiently strong coupling and low EJ/EC ratio. We will show measurements of density of quasiparticles on various qubits to discuss impact on coherence.