Perspectives and Progress in Qubit-Based Noise Characterization

Accurate characterization and control of open quantum systems exposed to realistic, spatio-temporally correlated noise are vital for exploiting the full potential of quantum technologies. Thanks to their exquisite sensitivity to the surrounding environment, qubits can be naturally considered as “spectrometers”, or sensors, of their own noise. Over the past decade, this realization has led to the development of quantum control techniques - collectively referred to as quantum noise spectroscopy (QNS) - for determining the noise spectral properties in a variety of qubit platforms. In this talk, I will survey the main QNS methods available for characterizing spectral properties of the noise in the frequency domain, and highlight some recent results. I will then discuss how important limitations of these approaches may be overcome by moving beyond the frequency domain, leveraging a recently introduced formalism for characterization and control based on the general mathematical notion of a frame. In particular, I will outline recent theoretical and experimental advances in digital QNS, including characterization of non-Gaussian noise.