Fluctuations of Energy-Relaxation Times in Superconducting Qubits

TL;DR

This paper investigates the unpredictable fluctuations in energy-relaxation times of superconducting qubits, identifying two-level-system defects as a primary cause, and aims to improve qubit stability through better calibration, design, and fabrication.

Contribution

It provides direct evidence linking two-level-system defects to relaxation time fluctuations in superconducting qubits, offering insights for stabilization strategies.

Findings

Two-level-system defects cause significant relaxation time fluctuations.

Qubits can be used as probes to identify defect contributions.

Insights enable potential stabilization of qubit performance.

Abstract

Superconducting qubits are an attractive platform for quantum computing since they have demonstrated high-fidelity quantum gates and extensibility to modest system sizes. Nonetheless, an outstanding challenge is stabilizing their energy-relaxation times, which can fluctuate unpredictably in frequency and time. Here, we use qubits as spectral and temporal probes of individual two-level-system defects to provide direct evidence that they are responsible for the largest fluctuations. This research lays the foundation for stabilizing qubit performance through calibration, design, and fabrication.