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Phys. Rev. A 71, 022318 (2005) [10 pages]

Implementation of projective measurements with linear optics and continuous photon counting

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Masahiro Takeoka and Masahide Sasaki
Quantum Information Technology Group, National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-kitamachi, Koganei, Tokyo 184-8795, Japan and CREST, Japan Science and Technology Agency, 1-9-9 Yaesu, Chuoh-ku, Tokyo 103-0028, Japan

Peter van Loock
Quantum Information Science Group, National Institute of Informatics (NII), 2-1-2 Hitotsubashi, Chiyoda, Tokyo 101-8430, Japan

Norbert Lütkenhaus
Quantum Information Theory Group, Zentrum für Moderne Optik, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany

Received 18 October 2004; published 23 February 2005

We investigate the possibility of implementing a given projection measurement using linear optics and arbitrarily fast feedforward based on the continuous detection of photons. In particular, we systematically derive the so-called Dolinar scheme that achieves the minimum-error discrimination of binary coherent states. Moreover, we show that the Dolinar-type approach can also be applied to projection measurements in the regime of photonic-qubit signals. Our results demonstrate that for implementing a projection measurement with linear optics, in principle, unit success probability may be approached even without the use of expensive entangled auxiliary states, as they are needed in all known (near-)deterministic linear-optics proposals.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevA.71.022318
DOI:
10.1103/PhysRevA.71.022318
PACS:
03.67.Hk, 03.65.Ta, 42.50.Dv
 
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