Physical Society Colloquium

From noisy qubits to qubit sensors: Highlights in quantum noise spectroscopy

Lorenza Viola

Department of Physics and Astronom
Dartmouth College

Accurate characterization of the noise influencing a quantum system of interest has far-reaching implications across fundamental quantum science and device technologies, ranging from microscopic modeling of decoherence dynamics to noise-optimized quantum control and quantum error correction. Thanks to their exquisite sensitivity to the surrounding environment, qubit systems can be naturally considered as “spectrometers”, or sensors, of their own noise. In this Colloquium, I will explain how formalizing this intuition has led, over the past decade, to the development of quantum control techniques - collectively referred to as “quantum noise spectroscopy” - for determining the noise spectral properties in a variety of settings and qubit platforms. I will then highlight some of our contributions, by describing in particular how protocols inspired by “spin-locking relaxometry” from nuclear magnetic resonance may be exploited for characterizing spatiotemporally correlated noise in qubit pairs, as experimentally demonstrated using a superconducting qubit circuit. I will conclude with an outlook on ongoing work and open problems in the field.