Information is usually extracted from a photon when a photodetector clicks. On the other hand, a single particle encloses part of the information it is carrying in its wavefunction which is usually lost in a single click. The wavefunction shape may be recovered reconstructing it with many detections, but there is no way to reconstruct it with a single detector’s click….
….in all but one case : when the wavefunction is localized.
If a photon wavefunction is localized the click on the detector also pinpoints the photon location so that much more information may be extracted.
In a recently published paper we demonstrate how to exploit this additional information in an optical fiber supporting transverse localization. Moreover by exploiting position and momentum complementarity we are able to encrypt information with a quantum key distribution protocol.