Adaptive Phase Measurements in Linear Optical Quantum Computation

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Title Adaptive Phase Measurements in Linear Optical Quantum Computation
Author Ralph, T C; Lund, A P; Wiseman, Howard Mark
Journal Name Journal of Optics B: Quantum and semiclassical optics
Year Published 2005
Place of publication Bristol, UK
Publisher Institute of Physics Publishing Ltd
Abstract Photon counting induces an effective non-linear optical phase shift in certain states derived by linear optics from single photons. Although this non-linearity is non-deterministic, it is sufficient in principle to allow scalable linear optics quantum computation (LOQC). The most obvious way to encode a qubit optically is as a superposition of the vacuum and a single photon in one mode-so-called 'single-rail' logic. Until now this approach was thought to be prohibitively expensive (in resources) compared to 'dual-rail' logic where a qubit is stored by a photon across two modes. Here we attack this problem with real-time feedback control, which can realize a quantum-limited phase measurement on a single mode, as has been recently demonstrated experimentally. We show that with this added measurement resource, the resource requirements for single-rail LOQC are not substantially different from those of dual-rail LOQC. In particular, with adaptive phase measurements an arbitrary qubit state α|0> + β|1> can be prepared deterministically.
Peer Reviewed Yes
Published Yes
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Copyright Statement Copyright 2005 Institute of Physics Publishing. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher.Please refer to the journal's website for access to the definitive, published version.
Volume 7
Page from S245
Page to S249
ISSN 1464-4266
Date Accessioned 2006-02-23
Language en_AU
Research Centre Centre for Quantum Dynamics
Faculty Faculty of Science
Subject PRE2009-Quantum Optics and Lasers
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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