Extremal quantum correlations and cryptographic security

• Applicant: Professor Dr. Reinhard F. Werner
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 199440898

Quantum cryptography is an established field of quantum information science and cryptographic security of quantum communication has been shown for a number of different protocols. Still, the fundamental structures of security against eavesdropping have not been fully examined. In a recent paper we identified a geometric feature, namely the extremality of quantum probability distributions, as a necessary and sufficient condition for device independent security. This is the strongest kind of security which does not rely on assumptions on the proper functioning of the physical devices. In the proposed research we want to develop new methods for the study and certification of secure probability distributions. We will also investigate approximately extremal correlations, aiming to show that these can still be used to generate secure keys with a positive rate.

• DFG Programme: Research Grants