  Sensing and metrology play an important role in fundamental science and
applications, by fulfilling the ever-present need for more precise data sets,
and by allowing to make more reliable conclusions on the validity of
theoretical models. Sensors are ubiquitous, they are used in applications
across a diverse range of fields including gravity imaging, geology,
navigation, security, timekeeping, spectroscopy, chemistry, magnetometry,
healthcare, and medicine. Current progress in quantum technologies inevitably
triggers the exploration of quantum systems to be used as sensors with new and
improved capabilities. This perspective initially provides a brief review of
existing and tested quantum sensing systems, before discussing future possible
directions of superconducting quantum circuits use for sensing and metrology:
superconducting sensors including many entangled qubits and schemes employing
Quantum Error Correction. The perspective also lists future research directions
that could be of great value beyond quantum sensing, e.g. for applications in
quantum computation and simulation.
