QUROPE Quantum Information Processing and Communication in Europe

Date: 23  May  2013

Place: Reading, UK

Main leader organizer: UK Crypto Developers Forum

Title of the talk: Quantum Key Distribution

Speaker: Grégoire Ribordy (IDQ)

We report on the experimental demonstration of an optical spin-wave memory, based on the atomic frequency comb (AFC) scheme, where the storage efficiency is strongly enhanced by an optical cavity. The cavity is of low finesse, but operated in an impedance matching regime to achieve high absorption in our intrinsically low-absorbing Eu3+:Y2SiO5 crystal.

Motivated by very recent experiments, we consider a scenario "\`a la Bell" in which two protagonists test the Clauser-Horne-Shimony-Holt (CHSH) inequality using a photon-pair source based on spontaneous parametric down conversion and imperfect photon detectors.

Quantum optics experiments frequently involve interfering single photons and coherent states. In the case of multi-photon experiments this requires that all photons are frequency degenerate. We report a simple and practical approach to generate coherent states that can be readily tuned to any wavelength required, for example by non-degenerate photon pair creation.

Harnessing nonlinearities strong enough to allow two single photons to interact with one another is not only a fascinating challenge but is central to numerous advanced applications in quantum information science. Currently, all known approaches are extremely challenging although a few have led to experimental realisations with attenuated classical laser light.

The program of the 6th winterschool on quantum communications deals with quantum cryptography, quantum computing and quantum repeaters. The goal of this event is to introduce this exciting topic in a relaxed and stimulating atmosphere to a general audience of physicists and computer scientists with little or no background in practical quantum communications. Special emphasis will be placed on practical aspects of quantum communications, such as the implementation of quantum key distribution systems and quantum repeaters, as well as concrete steps towards a quantum computer.

The program of the 6th winterschool on practical quantum communications deals with quantum cryptography, quantum computing and quantum repeaters. The goal of this event is to introduce this exciting topic in a relaxed and stimulating atmosphere to a general audience of physicists and computer scientists with little or no background in practical quantum communications. Special emphasis will be placed on practical aspects of quantum communications, such as the implementation of quantum key distribution systems and quantum repeaters, as well as concrete steps towards a quantum computer.