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Phys. Rev. A 71, 012309 (2005) [8 pages]

Quantum tomographic cryptography with Bell diagonal states: Nonequivalence of classical and quantum distillation protocols

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Dagomir Kaszlikowski1, Jenn Yang Lim1, D. K. L. Oi2, Frederick H. Willeboordse1, Ajay Gopinathan1,3, and L. C. Kwek3,1
1Department of Physics, National University of Singapore, Singapore 117 542, Singapore
2Centre for Quantum Computation, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom
3National Institute of Education, Nanyang Technological University, Singapore 639 798, Singapore

Received 1 September 2004; published 7 January 2005

We present a generalized tomographic quantum key distribution protocol in which the two parties share a Bell diagonal mixed state of two qubits. We show that if an eavesdropper performs a coherent measurement on many quantum ancilla states simultaneously, classical methods of secure key distillation are less effective than quantum entanglement distillation protocols. We also show that certain classes of Bell diagonal states are resistant to any attempt at incoherent eavesdropping.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevA.71.012309
DOI:
10.1103/PhysRevA.71.012309
PACS:
03.67.Dd, 89.70.+c
 
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