Driven-state relaxation of a coupled qubit-defect system in spin-locking measurements

TL;DR

This paper reveals that high-frequency two-level-system defects influence the relaxation rates in spin-locking noise spectroscopy of superconducting qubits, highlighting the need to consider both low- and high-frequency defects for accurate noise characterization.

Contribution

It demonstrates the impact of off-resonant high-frequency defects on driven-state relaxation in qubit-defect systems, expanding the understanding of noise mechanisms in superconducting qubits.

Findings

High-frequency defects affect spin-locking relaxation rates.

Both low- and high-frequency defects influence noise spectroscopy.

Interpretation of measurements must account for off-resonant defects.

Abstract

It is widely known that spin-locking noise-spectroscopy is a powerful technique for the characterization of low-frequency noise mechanisms in superconducting qubits. Here we show that the relaxation rate of the driven spin-locking state of a qubit can be significantly affected by the presence of an off-resonant high-frequency two-level-system defect. Thus, both low- and high-frequency defects should be taken into account in the interpretation of spin-locking measurements and other types of driven-state noise-spectroscopy.