J.-C. Boileau^1, K. Tamaki^2, J. Batuwantudawe^1, R. Laflamme^(1,2), J. M. Renes^(3,4)
1: Institute for Quantum Computing, University of Waterloo, Waterloo, ON, N2L 3G1, Canada. 2: Perimeter Institute for Theoretical Physics, 35 King Street North, Waterloo, ON, N2J 2W9, Canada. 3: Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131--1156, USA 4: IAKS Prof.Beth, Arbeitsgruppe Quantum Computing, Universität Karlsruhe, Am Fasanengarten 5, D-76131 Karlsruhe, Germany
Quantum key distribution (QKD) protocols are novel cryptographic techniques with security dependent only on the laws of quantum mechanics. Two prominent QKD schemes are the BB84 and B92 protocols that use four and two quantum states, respectively. A new family of three state protocols offering advantages over these was proposed in 2000 by Phoenix et al. [1], among them the symmetric trine spherical code. Until now, an error rate threshold for security of the trine QKD protocol has only been shown for the trivial intercept/resend eavesdropping strategy. I outline a recent proof of the unconditional security of the trine spherical code QKD protocol in the case of a bit error rate lower than 9.81% [2]. I explain how this proof applies to a version of the trine spherical code QKD protocol where the error rate is evaluated from the number of inconclusive events. I discuss some advantages of the symmetric trine spherical code and conclude with some simple experimental schemes for it.
[1] S. Phoenix, S. Barnett and A. Chefles, J. Mod. Opt., 47, 507 (2000). [2] J.C.B., K. Tamaki, J. Batuwantudawe, R. Laflamme, J. M. Renes, arXiv:quant-ph/0408085.