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Multiparameter estimation in networked quantum sensors

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journal contribution
posted on 2023-06-09, 09:19 authored by Timothy J Proctor, Paul A Knott, Jacob DunninghamJacob Dunningham
We introduce a general model for a network of quantum sensors, and we use this model to consider the following question: When can entanglement between the sensors, and/or global measurements, enhance the precision with which the network can measure a set of unknown parameters? We rigorously answer this question by presenting precise theorems proving that for a broad class of problems there is, at most, a very limited intrinsic advantage to using entangled states or global measurements. Moreover, for many estimation problems separable states and local measurements are optimal, and can achieve the ultimate quantum limit on the estimation uncertainty. This immediately implies that there are broad conditions under which simultaneous estimation of multiple parameters cannot outperform individual, independent estimations. Our results apply to any situation in which spatially localized sensors are unitarily encoded with independent parameters, such as when estimating multiple linear or nonlinear optical phase shifts in quantum imaging, or when mapping out the spatial profile of an unknown magnetic field. We conclude by showing that entangling the sensors can enhance the estimation precision when the parameters of interest are global properties of the entire network.

Funding

UK Quantum Technology Hub: NQIT-Networked Quantum Information Technologies; G1503; EPSRC-ENGINEERING & PHYSICAL SCIENCES RESEARCH COUNCIL; EP/M013243/1

History

Publication status

  • Published

File Version

  • Accepted version

Journal

Physical Review Letters

ISSN

0031-9007

Publisher

American Physical Society

Issue

8

Volume

120

Article number

a080501

Department affiliated with

  • Physics and Astronomy Publications

Research groups affiliated with

  • Sussex Centre for Quantum Technologies Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2017-12-12

First Open Access (FOA) Date

2017-12-12

First Compliant Deposit (FCD) Date

2017-12-12

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