Experimental implementation of the Quantum Private Queries
F. De Martini, Vittorio Giovannetti, Seth Lloyd, Lorenzo Maccone, Eleonora Nagali, Linda Sansoni, Fabio Sciarrino · arXiv (Cornell University) · 2009
The Quantum Private Query is a quantum cryptographic protocol to recover information from a database, preserving both user and data privacy: the user can test whether someone has retained information on which query was asked, and the database provider can bound the quantity of information released. Here we propose an optical scheme of this protocol which takes advantage of the different degrees of freedom of a single photon: it employs the photon's momentum as address qubits and its polarization as bus qubit. A proof-of-principle implementation of the scheme is carried out.