Thanks to the recent advances in quantum systems generation, manipulation and measurement, the new millennium witnessed the passage from the first to the second quantum revolution. Today, fundamental aspects of quantum theory, such as entanglement and the superposition principle, are at the core of many technologies able to outperform their classical counterparts (e.g., quantum information, metrology and sensing).
However, our comprehension of reality remains partial and veiled; a long debate is still ongoing on the peculiar aspects of quantum theory foundational axioms, like the nonlocality of quantum correlations, the ontological nature of the wave function and its collapse, the measurement process, the macro-objectivation problem (i.e., the transition from a microscopic probabilistic world to a macroscopic deterministic one).
Hence, although quantum mechanics looks almost mature, fundamental questions are still open, with implications also on quantum technologies. We address this topic through advanced experiments in quantum optics, such as the study of the concept of time in quantum mechanics (for example through the simulation of quantum particles traveling in time), the reconciliation between macroscopic irreversibility and quantum laws of the microscopic world ( temporally reversible) or the study of phenomena such as the quantum Zeno effect and its use in noise sensing techniques.
Furthermore, we develop and experimentally realize new quantum measurement paradigms in various regimes, from strong (projective) to “weak” (sequential weak measurements, protective measurement) characterized by peculiar properties overcoming the current limits of quantum measurements, paving the way for new research on the foundations of physics and innovative applications in the field of quantum technologies.