On QuantumCryptography and Secure Data Communication

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					   On Quantum Cryptography and Secure Data Communication
                                             Santanu Ganguly∗

    This work contrasts quantum information theory [1] and cryptography with the disciplines of steganog-
raphy, traffic security and classical cryptosystems as applied towards discreet communication. In quantum
computing, the laws of physics protect the information using the properties of quantum mechanics. Open-
air quantum key distribution with single photon source (SPS) has been demonstrated in experimental
conditions [2, 3, 4]. In the area of Quantum Cryptography, in particular, it has been shown that there
are intrinsic properties in Quantum Mechanics that will enable a Quantum Computer to produce results
not possible with a classical computer [5, 6, 7].
    In this paper we investigate the concept of development of Internet technologies based on the quantum
principles [8] of cryptography, secret sharing and teleportation. In particular, this paper is intended as
an introduction to the possibility of quantum optics giving birth to a new generation of communication
protocols over internet. It also addresses the complications arising from the atomic level structure of
a quantum computing system such as: decoherence, entanglement, quantum teleportation [9], unitary
transformations, and reversible universal gate structures. In the end, an analysis of a quantum full adder
constructed from these gates is presented along with suggestions for the creation of other elementary
Boolean gates.

[1] Shor, P. (2000), Quantum Information Theory: Results and Open Problems. Geom. Funct. Anal.
    (GAFA), Special Volume – GAFA 2000, 816-838.
[2] All´aume, R., Treussart, F., Messin, G., Dumeige, Y., Roch, J-F., Beveratos, A., Brouri-Tualle,
    R., Poizat, J-P., and Grangier, P. (2004), Experimental open-air quantum key distribution with a
    single-photon source. New Journal of Physics 6, 92.
[3] O’Brien, J.L. (2007), Optical Quantum Computing. Science (7 December) 318, no. 5856, 1567–1570.
[4] Kok, P., Munro, W.J., Nemoto, K., Ralph, T.C., Dowling, J.P. and Milburn, G.J. (2007), Linear
    optical quantum computing with photonic qubits. Reviews of Modern Physics (January 2007) 79,
    Issue 1, 135–174.
[5] Bennett, C.H., Brassard, G. and Ekert, A.K. (1992), Quantum cryptography. Scientific American,
    October 1992, 50–57.
[6] Shor, P.W. (1994), Algorithms for quantum computation: discrete logarithms and factoring. Proceed-
    ings 35th Annual Symposium on Foundations of Computer Science, 124–134.
[7] Bennett, C.H., Bessette, F., Brassard, G., Salvail, L. and Smolin, J. (1992), Experimental Quantum
    Cryptography. Journal of Cryptology 5, no. 1, 3–28.
[8] Slusher, D. (2006), Lecture at ARDA. http://www.cleoconference.org/materials/slusher.pdf
[9] Barrett, M.D., Chiaverini, J., Schaetz, T., Britton, J., Itano, W.M., Jost, J.D., Knill, E., Langer, C.,
    Leibfried, D., Ozeri, R. and Wineland, D.J. (2004), Deterministic quantum teleportation of atomic
    qubits. Nature (17 June) 429, 737–739.
[10] Hanson, R., Kouwenhoven, L.P., Petta, J.R., Tarucha, S. and Vandersypen, L.M.K. (2007), Spins in
    few-electron quantum dots. Reviews of Modern Physics (October 2007) 79, Issue 4, 1217–1265.
[11] Vazirani, U. (1994), Quotation from a newspaper article by Tom Siegfried, Science Editor of the
    Dallas Morning News.
   ∗ Swisscom AG, IPSS Laboratory, Binzring 17, 8045 Zurich, Switzerland; e-mail: santanu.ganguly@swisscom.com and

alternate e-mail: santanu.gangoly@gmail.com