SPAM-Robust Quantum Noise Spectroscopy*

Existing quantum noise spectroscopy (QNS) protocols allow for the reconstruction of the power spectral density of the noise experienced by a qubit. However, they are limited by the assumption that no state preparation and measurement (SPAM) errors are present, which is invalid in many of the current NISQ-era devices. We propose a modification to existing spin-locked based protocols that make them largely insensitive to the SPAM errors. Our modified protocol not only improves the reconstruction of the target noise spectra but, for noise sources that are non-classical, it also allows for the quantification of state preparation and measurement errors separately.