An article published in the scientific journal Optica describes the development of a new experimental device that explores the boundary between classical and quantum physics, allowing the simultaneous observation and investigation of phenomena from both worlds. The instrument was developed in Florence and is the result of collaboration within the extended partnership of the National Quantum Science and Technology Institute (NQSTI), involving the Department of Physics and Astronomy at the University of Florence, the National Institute of Optics of the National Research Council (CNR-INO), as well as the European Laboratory for Nonlinear Spectroscopy (LENS) and the Florence branch of the National Institute for Nuclear Physics (INFN).
It is well known that the study of matter, as we progress to increasingly smaller scales, shows radically different behaviors from those observed at the macroscopic scale: this is where quantum physics comes into play, helping to understand the properties of matter in the world of the infinitely small. While these phenomena have been studied separately until now, the instrument developed by CNR-INO researchers allows for the experimental exploration of matter's behavior from both perspectives.
The device takes advantage of the phenomenon of levitating nano-objects within a tightly focused laser beam, that is, the surprising ability of light to "trap" individual microscopic particles, a phenomenon first observed in the 1980s and further refined, in particular, by the American physicist Arthur Ashkin, who was awarded the Nobel Prize in Physics in 2018.
The Italian team, led by Francesco Marin (University of Florence and CNR-INO), has applied this technique to simultaneously trap, using beams of light of different colors, a pair of glass nanospheres. Within the optical trap, these spheres oscillate around their equilibrium point with very specific frequencies, allowing for the observation of both "classical" and "quantum" behaviors, the latter often being decidedly counterintuitive.
"These nano-oscillators are among the rare systems in which we can investigate the behavior of macroscopic objects in a highly controlled manner," says Marin. "The spheres are electrically charged and interact with each other, so the trajectory followed by one sphere is strongly dependent on the other. This opens the way for the study of collectively interacting nanosystems in both the classical and quantum regimes, thus allowing the experimental exploration of the subtle boundary between these two worlds."
The study is also made possible thanks to the support of two initiatives financed by the Ministry of University and Research with European Union funds as part of the #NextGenerationEU program (PNRR – National Recovery and Resilience Plan): the "National Quantum" partnership Science and Technology Institute" (NQSTI) and the "Integrated Infrastructure Initiative in Photonic and Quantum Science" (IPHOQS) infrastructure.
