Arxiv:Quant-Ph/0512071V2 14 Mar 2006 I Ulo:Byn Ieroptics Linear Beyond Outlook: VI
Linear optical quantum computing 1,2, 2 3 4 5, 6 4 Pieter Kok, ∗ W.J. Munro, Kae Nemoto, T.C. Ralph, Jonathan P. Dowling, and G.J. Milburn 1Department of Materials, Oxford University, Oxford OX1 3PH, UK 2Hewlett-Packard Laboratories, Filton Road Stoke Gifford, Bristol BS34 8QZ, UK 3National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan 4Centre for Quantum Computer Technology, University of Queensland, St. Lucia, Queensland 4072, Australia 5Hearne Institute for Theoretical Physics, Department of Physics and Astronomy, LSU, Baton Rouge LA, 70803, USA 6Institute for Quantum Studies, Department of Physics, Texas A&M University, 77843-4242, USA (Dated: February 1, 2008) Linear optics with photon counting is a prominent candidate for practical quantum computing. The protocol by Knill, Laflamme, and Milburn [Nature 409, 46 (2001)] explicitly demonstrates that efficient scalable quantum computing with single photons, linear optical elements, and projective measure- ments is possible. Subsequently, several improvements on this protocol have started to bridge the gap between theoretical scalability and practical implementation. We review the original theory and its improvements, and we give a few examples of experimental two-qubit gates. We discuss the use of realistic components, the errors they induce in the computation, and how these errors can be corrected. PACS numbers: 03.67.Hk, 03.65.Ta, 03.65.Ud Contents I. QUANTUM COMPUTING WITH LIGHT I. Quantum computing with light 1 Quantum computing has attracted much attention over A. Linear quantum optics 2 B. N port interferometers and optical circuits 4 the last ten to fifteen years, partly because of its promise C.
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