Article abstract
Nature Physics 5, 134 - 140 (2009)
Published online: 7 December 2008 | doi:10.1038/nphys1150
Subject Categories: Quantum physics | Optical physics | Information theory and computation
Simplifying quantum logic using higher-dimensional Hilbert spaces
Benjamin P. Lanyon1, Marco Barbieri1, Marcelo P. Almeida1, Thomas Jennewein1,2, Timothy C. Ralph1, Kevin J. Resch1,3, Geoff J. Pryde1,4, Jeremy L. O'Brien1,5, Alexei Gilchrist1,6 & Andrew G. White1
Abstract
Quantum computation promises to solve fundamental, yet otherwise intractable, problems across a range of active fields of research. Recently, universal quantum logic-gate sets—the elemental building blocks for a quantum computer—have been demonstrated in several physical architectures. A serious obstacle to a full-scale implementation is the large number of these gates required to build even small quantum circuits. Here, we present and demonstrate a general technique that harnesses multi-level information carriers to significantly reduce this number, enabling the construction of key quantum circuits with existing technology. We present implementations of two key quantum circuits: the three-qubit Toffoli gate and the general two-qubit controlled-unitary gate. Although our experiment is carried out in a photonic architecture, the technique is independent of the particular physical encoding of quantum information, and has the potential for wider application.
- Department of Physics and Centre for Quantum Computer Technology, University of Queensland, Brisbane 4072, Australia
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanng. 3, A-1090 Vienna, Austria
- Institute for Quantum Computing and Department of Physics & Astronomy, University of Waterloo, N2L 3G1, Canada
- Centre for Quantum Dynamics, Griffith University, Brisbane 4111, Australia
- Centre for Quantum Photonics, H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, University of Bristol, Merchant Venturers Building, Woodland Road, Bristol BS8 1UB, UK
- Physics Department, Macquarie University, Sydney 2109, Australia
Correspondence to: Benjamin P. Lanyon1 e-mail: lanyon@physics.uq.edu.au
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