What is quantum communication? Why quantum repeaters are important? What are quantum repeaters?

Quantum communication is the art of transferring a The distribution of quantum states over long distances is In the same way that classical communication uses
quantum state from one place to another. Traditionally, the essential for future applications such as quantum key amplifiers, it is possible to extend the distance over which
sender is named Alice and the receiver Bob. The basic distribution and quantum networks. The direct distribution of entanglement, & hence quantum information, is distributed
motivation is that quantum states code quantum information quantum states is limited by unavoidable transmission by chaining several quantum repeaters, one after the other,
- called qubits in the case of 2-dimensional Hilbert spaces losses of the channel used to transmit these quantum over successive fibre optic communication links.
and that quantum information allows one to perform tasks states. The direct approaches are limited to much less than
that could only be achieved far less efficiently, if at all, using 500 km, even under the most optimistic assumptions for
classical information. The best known example is Quantum technology evolution. In practice this has seen real world
Key Distribution (QKD). QKD implementations up to 150km, performed by the
Geneva group in Switzerland.
Quantum communication is built on a set of disruptive
concepts and technologies. It is driven by fascinating
physics and by promising applications. It requires a new
mix of competencies, from telecom engineering to
theoretical physics, from theoretical computer science to
mechanical and electronic engineering. First applications
have already found their way into niche markets, and many
university labs are working on futuristic quantum networks, The QuReP Quantum Repeater technology is centred
but most of the surprises are still ahead of us. Quantum around quantum light-matter interactions at the quantum
communication, and more generally quantum information level in ensembles of rare earth ions frozen in a crystal that
science and technologies, are here to stay and will have a store quantum information by coherent control of the
profound impact on the 21st century. quantum degrees of freedom.
The storage of quantum states allows us to wait for
successful transmission of a photon over an extended
What is Quantum Key Distribution? distance, thus overcoming the problems of loss.

This technology allows one to distribute sequence of The combination of entangled photons, quantum memories
random bit whose randomness and secrecy are guaranteed and high-performance singe-photon detectors is at the
by the laws of quantum physics. These sequences can then heart of the QuReP project and one of the key challenges
be used as secret keys with conventional cryptography for the commercial realisation of quantum repeaters.
techniques to guarantee the confidentiality of data
transmissions.
QuRep aims to:
Bring the device & system performance & specifications
to a mature, engineering-ready level
Integrate all of these elements into a coherent &
functional system
Ensure that the system is compatible with standard
optical fibre transmission systems
Demonstrate key generation over concatenated
quantum repeaters
The QuReP Consortium Contact
University of Geneva, Switzerland Project Coordinator
Nicolas Gisin Name: Prof. Nicolas Gisin
Lunds Universitet, Sweden Tel: +41 22 379 6597
Stefan Krll Fax: +41 22 379 3980
Universitt Paderborn, Germany E-mail: nicolas.gisin@unige.ch
Wolfgang Sohler Project Manager
CNRS, Centre National de la The aim of QuReP
Name: Dr Rob Thew
is to
Recherche Scientifique, France Tel: +41 22 379 6929
develop a Quantum Repeater:
Laboratoire Aim Cotton Fax: +41 22 379 3980 The elementary building block required to
Jean-Louis Le Guoet E-mail: robert.thew@unige.ch overcome current distance limitations for
Laboratoire de Chimie de la Matire Affiliation and Address long-distance quantum communication.
Condense de Paris
Universit de Genve
Philippe Goldner
20 rue de l'cole de mdecine
ID Quantique SA, Switzerland
1211 Genve Switzerland
Grgoire Ribordy
Web
The consortium competencies extend from fundamental
aspects of spectroscopy (CNRS (LCMCP)) to 3 groups that http://quantumrepeaters.eu
have already shown AFC memory functionality in different
systems (Uni Geneva, CNRS (LAC), Uni Lund), Uni Project reference: 247743
Paderborn is probably the leading applied physics groups in
Europe working on integrated photonic sources based on Instrument: Photonics STREP
nonlinear materials. Uni Geneva is one of the few groups in
Europe, and indeed the world, whose expertise covers all Timeline
aspects of quantum communication, from single photon
Start Date: 01/01/2010
detectors, photon sources, and quantum memories to the
theory of quantum communication architectures and End Date: 31/12/2012
security. The industrial partner IDQ, are the world leaders in
the commercialisation of quantum communication. They Budget
have a proven experience in industrialising advanced
quantum technologies and are ready to exploit the next Overall Cost: 2 481 878,00
generation of entanglement-enabled technologies that Funding: 1 900 000,00
should arise from this project.