Exploring the Quantum-Classical Transition with Trapped Nanospheres

Researchers from the National Quantum Science and Technology Institute (NQSTI), in collaboration with the University of Florence, the National Institute of Optics (CNR-INO), the LENS Laboratory, and INFN, have developed a device capable of simultaneously observing classical and quantum phenomena. The study, published in Optica, investigates the boundary between these regimes using optically levitated glass nanospheres.

The instrument was developed through joint efforts at the European Laboratory for Nonlinear Spectroscopy (LENS), the Florence branch of the National Institute for Nuclear Physics (INFN), the Department of Physics and Astronomy at the University of Florence, the National Institute of Optics of the National Research Council (CNR-INO), and NQSTI.

Quantum mechanics describes the behavior of matter at microscopic scales, where physical properties deviate significantly from macroscopic classical systems. While classical and quantum behaviors have traditionally been studied separately, the device developed by CNR-INO researchers enables experimental investigation of both regimes within a single system.

The system utilizes optical levitation, a phenomenon in which tightly focused laser beams confine nanoscale objects in free space. First observed in the 1980s, this effect was further refined by Arthur Ashkin, who was awarded the 2018 Nobel Prize in Physics for his contributions to optical trapping.

The Italian research team, led by Francesco Marin from the University of Florence and CNR-INO, implemented this technique to trap two glass nanospheres simultaneously using laser beams of different wavelengths. The confined particles oscillate within the optical potential at well-defined frequencies, allowing for direct observation of both classical and quantum behaviors.

These nano-oscillators are among the rare systems in which we can investigate the behavior of macroscopic objects in a highly controlled manner. 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.

Francesco Marin, University of Florence