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Nanofiber Quantum Networks (NanoQuaNt)
Date du début: 1 juin 2014, Date de fin: 31 mai 2019 PROJET  TERMINÉ 

We propose to establish nanofiber-based atom-light interfaces as quantum-enabled fiber-optical components for quantum information processing and communication (QIPC). The key ingredient of this interface is a nanofiber-based optical dipole trap which stores laser-cooled atoms in the evanescent field surrounding the nanofiber. In this evanescently coupled atom-waveguide-system, even a few hundred atoms are already optically dense for near-resonant photons propagating through the nanofiber. In combination with the proven good coherence properties of nanofiber-trapped atoms, these highly efficient light-matter interfaces are thus perfectly suited for the implementation of practical QIPC devices. More specifically, the first goal of this project is to realize quantum memories which allow one to directly store and retrieve the quantum state of fiber-guided photons. The efficiency of the retrieval process will highly benefit from the fact that conservation of energy and momentum stabilizes the emission of the stored light into the nanofiber-guided mode. Furthermore, nanofiber-coupled atomic ensembles can provide a strong optical non-linearity which, due to the waveguide-geometry, scales with the square root of the length of the sample and can be much larger than for freely propagating light beams. The second goal of this project is to explore and to maximize this non-linearity until it prevails down to the single photon level. This single-photon non-linearity would enable optical quantum switches and photon-photon quantum gates which are essential for implementing deterministic optical quantum computation. The final goal is then to interconnect these components in order to demonstrate three different fiber-optical quantum network applications: highly efficient photon counting using fiber-coupled quantum memories, highly efficient heralded entanglement of two fiber-coupled quantum memories, and a non-linear interaction between two single-photon pulses.