Quantum metrology in the presence of limited data

Rubio Jiménez, Jesús and Dunningham, Jacob A (2019) Quantum metrology in the presence of limited data. New Journal of Physics. ISSN 1367-2630

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Abstract

Quantum metrology protocols are typically designed around the assumption that we have an abundance of measurement data, but recent practical applications are increasingly driving interest in cases with very limited data. In this regime the best approach involves an interesting interplay between the amount of data and the prior information. Here we propose a new way of optimising these schemes based on the practically-motivated assumption that we have a sequence of identical and independent measurements. For a given probe state we take our measurement to be the best one for a single shot and we use this sequentially to study the performance of different practical states in a Mach-Zehnder interferometer when we have moderate prior knowledge of the underlying parameter. We find that we recover the quantum Cramér-Rao bound asymptotically, but for low data counts we find a completely different structure. Despite the fact that intra-mode correlations are known to be the key to increasing the asymptotic precision, we find evidence that these could be detrimental in the low data regime and that entanglement between the paths of the interferometer may play a more important role. Finally, we analyse how close realistic measurements can get to the bound and find that measuring quadratures can improve upon counting photons, though both strategies converge asymptotically. These results may prove to be important in the development of quantum enhanced metrology applications where practical considerations mean that we are limited to a small number of trials.

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
Q Science > QC Physics
Depositing User: Alice Jackson
Date Deposited: 28 Feb 2019 10:48
Last Modified: 01 Jul 2019 19:47
URI: http://sro.sussex.ac.uk/id/eprint/82178

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Project NameSussex Project NumberFunderFunder Ref
UK Quantum Technology Hub: NQIT-Networked Quantum Information TechnologiesG1503EPSRC-ENGINEERING & PHYSICAL SCIENCES RESEARCH COUNCILEP/M013243/1