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

• Final Report Year: 2017

Final Report Abstract

In this project we developed a novel scheme for analyzing the security of quantum key distribution of continuous variable quantum protocols. Our scheme is based on the application of the entropic uncertainty relation and can be used to certify security against the most general coherent attacks under experimentally feasible conditions. The security proof accounts for finite size effects, i.e., deviations from the ideal situation of infinite repetition of the protocol. The security does furthermore not depend on any assumptions on the devices of the receiver, so the security is one-sided device independent. In collaboration with experimental physicists we were able to demonstrate the feasibility of the protocol in a table-top experiment using squeezed Gaussian quantum states. The implementation was done at a light wavelength of 1550nm, which makes the use of standard telecom technology possible. To the best of our knowledge, this was the first implementation of continuous variable QKD secure against collective attacks with finite key analysis and an actually performed post processing.

Publications

• Strong Einstein- Podolsky-Rosen entanglement from a single squeezed light source. Phys. Rev. A, 83:052329 (2011)
  T. Eberle, V. Händchen, J. Duhme, T. Franz, R.F. Werner, and R. Schnabel
  
• Continuous variable quantum key distribution: Finite-key analysis of composable security against coherent attacks. Phys. Rev. Lett., 109:100502 (2012)
  F. Furrer, T. Franz, M. Berta, A. Leverrier, V.B. Scholz, M. Tomamichel, and R.F. Werner
  
• Security of continuous-variable quantum key distribution and aspects of device-independent security, Dissertation, Leibniz University Hannover (2012)
  Fabian Furrer
  
• Gaussian entanglement for quantum key distribution from a single-mode squeezing source. New Journal of Physics 15 (5), 053049 (2013)
  T. Eberle, V. Händchen, J. Duhme, T. Franz, R.F. Werner, and R. Schnabel
  
• Implementation of continuous-variable quantum key distribution with composable and one-sided-device-independent security against coherent attacks, Nature Communications, 6:8795. (2015)
  T. Gehring, V. Händchen, J. Duhme, F. Furrer, T. Franz, C. Pacher, R.F. Werner und R. Schnabel
  
• Quantum key security: theory and analysis of experimental realisations, Dissertation, Leibniz University Hannover (2015)
  Jörg Duhme