Optimal input states and feedback for interferometric phase estimation

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Title Optimal input states and feedback for interferometric phase estimation
Author Berry, D. W.; Wiseman, Howard Mark; Breslin, J. K.
Journal Name Physical Review A: Atomic, Molecular and Optical Physics
Editor Bernd Crasemann
Year Published 2001
Place of publication USA
Publisher American Physical Society
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 by 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.
Peer Reviewed Yes
Published Yes
Publisher URI http://prola.aps.org/abstract/PRA/v63/i5/e053804
Copyright Statement Copyright 2001 American Physical Society. Reproduced in accordance with the copyright policy of the publisher. This journal is available online - use hypertext links.
Volume 63
Issue Number 5
Page from 053804.1
Page to 053804.11
ISSN 1050-2947
Date Accessioned 2002-04-15
Language en_AU
Research Centre Centre for Quantum Dynamics
Faculty Faculty of Science
Subject Theoretical Physics
URI http://hdl.handle.net/10072/3791
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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