The ability to distribute secret keys with information-theoretic security is undoubtedly one of the most important achievements of the field of quantum information processing and communications. Quantum key distribution (QKD) protocols in which the key information is encoded on quantum continuous variables, such as the values of quadrature components of coherent states of light, present the major advantage that they only require standard telecommunication technology, and in particular, that they do not use photon counters. After introducing such protocols, we present the state-of-the-art in long-distance fiber optic experiments for continuous-variable quantum key distribution (CV-QKD). Furthermore, we discuss the resistance of CV-QKD systems to eavesdropping attacks based on auxiliary information channels that are typically not taken into account in security proofs, as well as avenues to exploit the standard components employed in such systems with the goal of developing silicon photonic chips, opening the way to the widespread use of this technology for high-security applications. We will also present other important quantum cryptographic tasks that will be at the heart of future quantum communication networks and will conclude with the main challenges in the field.
Eleni DIAMANTI
Laboratoire d’Informatique de Paris 6 (LIP6)
4 place Jussieu
75252 PARIS cedex 05
https://www.lip6.fr/
