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Gaussian systems for quantum-enhanced multiple phase estimation
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Gagatsos, Christos N., Branford, Dominic and Datta, Animesh (2016) Gaussian systems for quantum-enhanced multiple phase estimation. Physical Review A, 94 (4). 042342. doi:10.1103/PhysRevA.94.042342 ISSN 1050-2947.
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Official URL: http://doi.org/10.1103/PhysRevA.94.042342
Abstract
For a fixed average energy, the simultaneous estimation of multiple phases can provide a better total precision than estimating them individually. We show this for a multimode interferometer with a phase in each mode, using Gaussian inputs and passive elements, by calculating the covariance matrix. The quantum Cram\backslash'{e}r-Rao bound provides a lower bound to the covariance matrix via the quantum Fisher information matrix, whose elements we derive to be the covariances of the photon numbers across the modes. We find our simultaneous strategy to yield no more than a factor of two improvement in total precision. In spite of the Gaussian nature of the problem, these elements require the calculation of non-Gaussian integrals, which we accomplish analytically. We prove that this bound can be saturated. Our work shows that no modal entanglement is necessary for simultaneous quantum-enhanced estimation of multiple phases.
Item Type: | Journal Article | ||||||||
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Subjects: | Q Science > QA Mathematics Q Science > QC Physics |
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||||
Library of Congress Subject Headings (LCSH): | Quantum theory , Gaussian processes | ||||||||
Journal or Publication Title: | Physical Review A | ||||||||
Publisher: | American Physical Society | ||||||||
ISSN: | 1050-2947 | ||||||||
Official Date: | 28 October 2016 | ||||||||
Dates: |
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Volume: | 94 | ||||||||
Number: | 4 | ||||||||
Article Number: | 042342 | ||||||||
DOI: | 10.1103/PhysRevA.94.042342 | ||||||||
Status: | Peer Reviewed | ||||||||
Publication Status: | Published | ||||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||||
Date of first compliant deposit: | 31 October 2016 | ||||||||
Date of first compliant Open Access: | 3 November 2016 | ||||||||
Funder: | Engineering and Physical Sciences Research Council (EPSRC) | ||||||||
Grant number: | (EP/K04057X/2), (EP/M01326X/1), (EP/M013243/1) | ||||||||
Open Access Version: |
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