title: Interference at the Single Photon Level Along Satellite-Ground Channels.
abstract: Quantum interference arising from the superposition of states is striking evidence of the validity of quantum mechanics, confirmed in many experiments and also exploited in applications. However, as for any scientific theory, quantum mechanics is valid within the limits in which it has been experimentally verified. In order to extend such limits, it is necessary to observe quantum interference in unexplored conditions such as moving terminals at large distances in space. Here, we experimentally demonstrate single photon interference at a ground station due to the coherent superposition of two temporal modes reflected by a rapidly moving satellite a thousand kilometers away. The relative speed of the satellite induces a varying modulation in the interference pattern. The measurement of the satellite distance in real time by laser ranging allows us to precisely predict the instantaneous value of the interference phase. We then observed the interference patterns with a visibility up to 67% with three different satellites and with a path length up to 5000 km. Our results attest to the viability of photon temporal modes for fundamental tests of physics and quantum communication in space.
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, Università degli Studi di Padova, Padova 35131, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vallone
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, Università degli Studi di Padova, Padova 35131, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Dequal
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, Università degli Studi di Padova, Padova 35131, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Tomasin
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, Università degli Studi di Padova, Padova 35131, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Vedovato
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, Università degli Studi di Padova, Padova 35131, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Schiavon
authors.affiliation: e-GEOS spa, Matera 75100, Italy.
authors.forename: Vincenza
authors.initials: V
authors.lastname: Luceri
authors.affiliation: Matera Laser Ranging Observatory, Agenzia Spaziale Italiana, Matera 75100, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bianco
authors.affiliation: Dipartimento di Ingegneria dell'Informazione, Università degli Studi di Padova, Padova 35131, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Villoresi