title: Experimental observation of impossible-to-beat quantum advantage on a hybrid photonic system.
abstract: Quantum resources outperform classical ones for certain communication and computational tasks. Remarkably, in some cases, the quantum advantage cannot be improved using hypothetical postquantum resources. A class of tasks with this property can be singled out using graph theory. Here we report the experimental observation of an impossible-to-beat quantum advantage on a four-dimensional quantum system defined by the polarization and orbital angular momentum of a single photon. The results show pristine evidence of the quantum advantage and are compatible with the maximum advantage allowed using postquantum resources.
authors.affiliation: Dipartimento di Fisica della Sapienza Università di Roma, Roma 00185, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Nagali
authors.forename: Vincenzo
authors.initials: V
authors.lastname: D'Ambrosio
authors.forename: Fabio
authors.initials: F
authors.lastname: Sciarrino
authors.forename: Adán
authors.initials: A
authors.lastname: Cabello