Optimal input states and feedback for interferometric phase estimation

Berry, D. W., Wiseman, H. M. and Breslin, J. K. (2001) Optimal input states and feedback for interferometric phase estimation. Physical Review A, 63 5: 053804-053804. doi:10.1103/PhysRevA.63.053804

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Author Berry, D. W.
Wiseman, H. M.
Breslin, J. K.
Title Optimal input states and feedback for interferometric phase estimation
Journal name Physical Review A   Check publisher's open access policy
ISSN 1050-2947
Publication date 2001
Sub-type Article (original research)
DOI 10.1103/PhysRevA.63.053804
Open Access Status File (Publisher version)
Volume 63
Issue 5
Start page 053804
End page 053804
Total pages 11
Editor B. Crasemann
Place of publication United States
Publisher American Physical Society
Collection year 2001
Language eng
Subject C1
240201 Theoretical Physics
780102 Physical sciences
Abstract We derive optimal N-photon two-mode input states for interferometric phase measurements. Under canonical measurements the phase variance scales as N-2 for these states, as compared to N-1 or N-1/2 for states considered bq previous authors. We prove, that it is not possible to realize the canonical measurement by counting photons in the outputs of the interferometer, even if an adjustable auxiliary phase shift is allowed in the interferometer. However. we introduce a feedback algorithm based on Bayesian inference to control this auxiliary phase shift. This makes the measurement close to a canonical one, with a phase variance scaling slightly above N-2. With no feedback, the best result (given that the phase to be measured is completely unknown) is a scaling of N-1. For optimal input states having up to four photons, our feedback scheme is the best possible one, but for higher photon numbers more complicated schemes perform marginally better.
Keyword Optics
Physics, Atomic, Molecular & Chemical
Optimal Quantum Measurements
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mathematics and Physics
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Citation counts: TR Web of Science Citation Count  Cited 36 times in Thomson Reuters Web of Science Article | Citations
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Created: Tue, 14 Aug 2007, 16:14:28 EST