Optimal States and Almost Optimal Adaptive Measurements for Quantum Interferometry
Author(s)
Berry, DW
Wiseman, HM
Griffith University Author(s)
Year published
2000
Metadata
Show full item recordAbstract
We derive the optimal N-photon two-mode input state for obtaining an estimate f of the phase difference between two arms of an interferometer. For an optimal measurement [B. C. Sanders and G. J. Milburn, Phys. Rev. Lett. 75, 2944 (1995)], it yields a variance (?f)2?p2/N2, compared to O(N-1) or O(N-1/2) for states considered by previous authors. Such a measurement cannot be realized by counting photons in the interferometer outputs. However, we introduce an adaptive measurement scheme that can be thus realized, and show that it yields a variance in f very close to that from an optimal measurementWe derive the optimal N-photon two-mode input state for obtaining an estimate f of the phase difference between two arms of an interferometer. For an optimal measurement [B. C. Sanders and G. J. Milburn, Phys. Rev. Lett. 75, 2944 (1995)], it yields a variance (?f)2?p2/N2, compared to O(N-1) or O(N-1/2) for states considered by previous authors. Such a measurement cannot be realized by counting photons in the interferometer outputs. However, we introduce an adaptive measurement scheme that can be thus realized, and show that it yields a variance in f very close to that from an optimal measurement
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Journal Title
Physical Review Letters
Volume
85
Issue
24
Publisher URI
Copyright Statement
© 2000 American Physical Society. Reproduced in accordance with the copyright policy of the publisher. This journal is available online - use hypertext links.
Subject
Mathematical sciences
Physical sciences
Engineering
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