Resetting a Superconducting Qubit with a Compact Colder Resistive Dissipator below the Qubit Frequency

Abstract

Efficient qubit reset has become a key requirement for large-scale superconducting quantum processors, as initialization fidelity increasingly lags behind gate performance and quantum error correction demands rapid, high-fidelity state re-initialization. This work proposes a compact on-chip dissipator consisting of two transmon dissipation modes and a thin-film resistor, and experimentally demonstrates an unconditional reset protocol. With no additional control lines and negligible impact on the qubit $T_1$, the effective temperature of the transmon qubit is reduced from $49$~mK to $35$~mK. Quantum process tomography is employed to benchmark the reset process, achieving a process error of $0.0028$. This reset protocol is robust to pulse parameter deviations, thereby relaxing calibration requirements. The dissipator architecture provides a practical, calibration-friendly reset solution for large-scale superconducting quantum processors.