Understanding and Mitigating TLS-Induced High-Order Decoherence in Superconducting Qubits

Two-level systems (TLSs) on uncontrolled device surfaces are believed to cause both depolarization and dephasing in superconducting qubits. They are related to a number of noise channels, including the dielectric, charge and flux noise. Understanding and mitigating the TLS-related decoherence have been a central task towards improving the performance of superconducting quantum processors. In this presentation, we focus on the high-order effect of qubit-TLS coupling on both qubit depolarization and dephasing. Based on these results, we introduce mitigation strategies to reduce the loss of qubits while maintaining their controllability.