Demonstrating an absolute quantum advantage in direct absorption measurement

Paul-Antoine Moreau; Javier Sabines-Chesterking; Rebecca Whittaker; Siddarth K. Joshi; Patrick Birchall; Alex McMillan; John G. Rarity; Jonathan C. F. Matthews

arXiv · 1611.07871

Demonstrating an absolute quantum advantage in direct absorption measurement

Paul-Antoine Moreau·Javier Sabines-Chesterking·Rebecca Whittaker·Siddarth K. Joshi·Patrick Birchall·Alex McMillan·John G. Rarity·Jonathan C. F. Matthews

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Abstract

Engineering apparatus that harness quantum theory offers practical advantages over current technology. A fundamentally more powerful prospect is the long-standing prediction that such quantum technologies could out-perform any future iteration of their classical counterparts, no matter how well the attributes of those classical strategies can be improved. Here, we experimentally demonstrate such an instance of \textit{absolute} advantage per photon probe in the precision of optical direct absorption measurement. We use correlated intensity measurements of spontaneous parametric downconversion using a commercially available air-cooled CCD, a new estimator for data analysis and a high heralding efficiency photon-pair source. We show this enables improvement in the precision of measurement, per photon probe, beyond what is achievable with an ideal coherent state (a perfect laser) detected with $100\%$ efficient and noiseless detection. We see this absolute improvement for up to $50\%$ absorption, with a maximum observed factor of improvement of 1.46. This equates to around $32\%$ reduction in the total number of photons traversing an optical sample, compared to any future direct optical absorption measurement using classical light.

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Paul-Antoine Moreau, Javier Sabines-Chesterking, Rebecca Whittaker, Siddarth K. Joshi, Patrick Birchall, Alex McMillan, John G. Rarity, Jonathan C. F. Matthews. 2016-11-23. Demonstrating an absolute quantum advantage in direct absorption measurement. https://arxiv.org/abs/1611.07871

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