DELPHI · Deterministic Logical Photon-Photon Interactions

The main objective of this proposal is to design and implement a novel scheme for efficient, deterministic, lossless photon-photon interactions, and to exploit it to achieve logical processing and quantum measurements on optical light beams. For that purpose, we will create, study and exploit a new transparent medium, based on the transient excitation of Rydberg polaritons, where the optical non-linearities are so large that they can act at the single photon level. These techniques will be applied to perform quantum measurements and manipulations of light beams. This will include the deterministic generation of single photons and optical Schrödinger's cat states, the implementation of quantum non-demolition (QND) measurements for the photon number and the parity operators, and the demonstration of controlled-phase and controlled-not quantum gates. These operations will be implemented in the optical domain, where they can be combined with efficient propagation in free space or in optical fibers, and with high efficiency detectors already available, in order to open an avenue towards a fully deterministic quantum engineering of light.