Physical approaches and perspectives
State of the art
Dealing with implementation issues at an applied level requires close collaboration between quantum hackers and those building, and even selling, the QKD systems and technologies. This approach has been well demonstrated for recent detection attacks [2]. DI-QKD, on the other hand, is a relatively new concept and its experimental application requires unprecedented performance of the systems and component technologies. Nonetheless, a couple of recent papers have started to bring this into the realms of experimental feasibility [3, 4]. Central to this was the concept of heralded photon amplifiers [5], which have also been realised experimentally in the visible [6, 7] and more recently, telecom regimes[8]. Self-Testing is another related concept where the effort is to minimise assumptions and to help better characterise quantum systems and technologies. To date this has primarily been a theoretical effort for the moment [9-11]. The adaptation and demonstration of DI-QKD will also be important for future secure networks. In a further extension of this idea, heralded photon amplifiers have been proposed in a recent quantum repeater protocol [12] that is not only one of the most efficient but it also hints at the potential for DI scenarios across quantum networks.
Challenges
Both quantum hacking and device independent security have similar goals, but approach the task from opposite directions: Both have the aim of minimising the assumptions involved in secure quantum communication systems and to bridge the gap between the theoretical proofs and the security of the final implementation. European theory groups have been a driving force in this area, especially for the later, although experimental initiatives have already started in several European groups, as well as in Singapore, Canada and Australia. Some of the key challenges are:
Key references
[1] A. Ekert, Phys. Rev. Lett. 67, 661 (1991)
[2] L. Lydersen et al., Nature Photonics 4, 686 (2010)
[3] A. Acin et al., Phys. Rev. Lett. 98, 230501 (2007)
[4] N. Gisin, S. Pironio and N. Sangouard, Phys. Rev. Lett. 105, 070501 (2010)
[5] T. Ralph and A. Lund, Quantum Communication Measurement and Computing Proceedings of 9th International Conference, Ed. A.Lvovsky, 155 (AIP, New York 2009) - arXiv:0809.0326v1 (2009)
[6] G. Y. Xiang et al., Nature Photonics 4, 316 (2010)
[7] F. Ferreyrol et al. Phys. Rev. Lett. 104, 123603 (2010)
[8] C. I. Osorio et al., Phys. Rev. A 86, 023815 (2012)
[9] D. Mayers and A. Yao, Quantum Inform. Comput. 4 (2004)
[10] M. McKague, T. H. Yang, V. Scarani, arXiv:1203.2976v1 (2012)
[11] C. C. W. Lim et al., arXiv:1208.0023 (2012)
[12] J. Minar, H. de Riedmatten and N. Sangouard, Phys. Rev. A 85, 032313 (2012)