Knott, P A, Proctor, T J, Hayes, A J, Ralph, J F, Kok, P and Dunningham, J A (2016) Local versus global strategies in multi-parameter estimation. Physical Review A, 94 (6). a2312. ISSN 1050-2947

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Abstract

We consider the problem of estimating multiple phases using a multi-mode interferometer. In this setting we show that while global strategies that estimate all the phases simultaneously can lead to high precision gains, the same enhancements can be obtained with local strategies where each phase is estimated individually. A key resource for the enhancement is shown to be a large particle-number variance in the probe state, and for states where the total particle number is not fixed, this can be obtained for mode-separable states and the phases can be read out with local measurements. This has important practical implications because local strategies are generally preferred to global ones for their robustness to local estimation failure, flexibility in the distribution of resources, and comparatively easier state preparation. We obtain our results by analyzing two different schemes: the first uses a set of interferometers, which can be used as a model for a network of quantum sensors, and the second looks at measuring a number of phases relative to a reference, which is concerned primarily with quantum imaging.

Item Type:	Article
Schools and Departments:	School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups:	Atomic, Molecular and Optical Physics Research Group
Subjects:	Q Science > QC Physics
Depositing User:	Richard Chambers
Date Deposited:	22 Nov 2016 11:39
Last Modified:	09 Sep 2017 19:46
URI:	http://srodev.sussex.ac.uk/id/eprint/65580

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