Systematic Characterization of Transmon Qubit Stability with Thermal Cycling.

Area of Science:

• Quantum Computing
• Superconducting Circuits
• Materials Science

Background:

• Qubit stability is crucial for quantum processors.
• Superconducting qubits are sensitive to environmental changes.
• Longitudinal studies are needed to understand qubit parameter drift.

Purpose of the Study:

• To characterize the long-term temporal stability and reproducibility of superconducting transmon qubit parameters.
• To investigate the impact of thermal cycling on qubit performance and environmental factors.
• To establish a hierarchy of stability for superconducting hardware components.

Main Methods:

• Longitudinal characterization of 27 frequency-tunable transmon qubits over one year.
• Analysis across four thermal cycles.
• Frequency-dependent relaxation spectroscopy and T1 Spectral Topography Fidelity metric.

Main Results:

• Intrinsic qubit parameters (frequency, T1) show high robustness against thermal stress (deviations <0.5%).
• Environmental variables (magnetic flux offsets, TLS defects) reconfigure stochastically after each thermal cycle.
• Thermal cycling acts as a 'hard reset' for the defect environment, causing spectral randomization.

Conclusions:

• Fabrication quality of superconducting qubits is preserved across thermal cycles.
• The specific noise realization is statistically distinct after each cycle.
• Automated recalibration strategies are essential for large-scale quantum systems.