Ricerc@Sapienza

The vastly growing field on quantum computers highlights ever more that current classical communication might soon no longer meet the stringent security requirements for data transfer, making the development of new communication systems a pressing need. A promising solution is the transfer from classical networks to quantum networks based on information encoding in single photons, which would allow the exploitation of the already established communication infrastructure consisting of fibers and satellites. Long-distance communication, however, suffers from signal loss, pointing out the need for signal amplification and repetition. Since classical amplification is no longer feasible in quantum networks - due to the no-cloning theorem - quantum repeaters need to be developed. We propose a quantum repeater based on entanglement, to build up a quantum network by stringing together multiple quantum repeaters. The encrypted signal can then be transferred from quantum repeater to quantum repeater via entanglement swapping. The implementation of entanglement swapping sets stringent requirements on the efficiency, degree of entanglement, photon/indistinguishability as well as wavelength/tunability, of the entangled photon source. All these requirements have already been demonstrated using semiconductor quantum dots, thus making them promising candidates for future quantum repeaters. However, the requirements have only been achieved individually and an ultimate source combining all, in order to achieve remote entanglement swapping, is still missing. In this project we propose the first deomstration of remote entanglement swapping, enabled by a semiconductor-based quantum repeater device, and thus, setting a milestone for the generation of quantum networks.