Learning the noise fingerprint of quantum devices

In the quantum technologies context, no quantum device can be considered an isolated (ideal) quantum system. For this reason, the acronym Noisy Intermediate-Scale Quantum (NISQ) technology has been recently introduced [1] to identify the class of early devices in which noise in quantum gates dramatically limits the size of circuits and algorithms that can be reliably performed [2, 3]. As early quantum devices become more widespread, a question that naturally arises is to understand, at the experimental level, whether in a generic quantum device the signature left by inner noise processes exhibits universal features or is characteristic of the specific quantum platform. Moreover, one may wonder to determine if such a noise signature has a time-dependent profile or can be effectively considered stable, in the sense of constant over time, while the device is operating. The answers to these questions are expected to be crucial in defining a proper strategy to mitigate the influence of noise and systematic errors [4-8], possibly going beyond standard quantum sensing techniques [9-14] and overcoming current limitations on probes dimension and resolution [9, 10, 15-18].