Superconducting quantum circuits are microwave circuits that display macroscopic quantum phenomena.
Like their classical counterparts, they can be designed by combining lumped or distributed elements—such
as inductors and resonators—but with degrees of freedom governed by the laws of quantum mechanics. By
incorporating Josephson junctions, which are nonlinear superconducting elements, these circuits can realize
two-level quantum systems, or qubits. In recent years, this approach has laid the foundation—pursued by
many companies—for the development of large-scale quantum computers.

Beyond quantum computing, the precise control and measurement of individual quanta, as well as the ability
to engineer their interactions with each other and with multilevel (N-level) systems, are opening new
frontiers in fundamental physics. These include the detection of dark matter and fifth forces, as well as the
study of quantum many-body systems.

Quantum sensing with superconducting qubits has advanced from proof-of-principle demonstrations to
practical applications in fundamental physics experiments, delivering unprecedented improvements in
sensitivity. Quantum superposition and entanglement have enabled key breakthroughs such as Quantum
Non-Demolition (QND) detection of single photons and the detection of itinerant photons—two essential
capabilities for microwave-photon detectors in light dark matter experiments.

Moreover, quantum many-body physics is now being explored through analog quantum simulations. These
simulations mimic the dynamics of complex quantum systems by using quantum circuits whose
Hamiltonians closely replicate those of the systems under investigation.

In this seminar, I will present recent advances in quantum sensing and outline our plans for analog quantum
simulation using superconducting circuits at INFN.