arXiv subjects

Javier Sabines-Chesterking

Publications and source records attributed to Javier Sabines-Chesterking.

3 recordsLinked to original sources

arXiv2019

Quantum Absorbance Estimation and the Beer-Lambert Law

The utility of transmission measurement has made it a target for quantum enhanced measurement strategies. Here we find if the length of an absorbing object is a controllable variable, then via the Beer-Lambert law, classical strategies can be optimised to reach within 83% of the absolute quantum limit. Our analysis includes experimental losses, detector noise, and input states with arbitrary photon statistics. We derive optimal operating conditions for both classical and quantum sources, and observe experimental agreement with theory using Fock and thermal states.

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arXiv2016

Beating the Shot-Noise Limit with Sources of Partially-Distinguishable Photons

Quantum metrology promises high-precision measurements beyond the capability of any classical techniques, and has the potential to be integral to investigative techniques. However, all sensors must tolerate imperfections if they are to be practical. Here we show that photons with perfectly overlapped modes, which are therefore fully indistinguishable, are not required for quantum-enhanced measurement, and that partially-distinguishable photons do not have to be engineered to mitigate the adverse effects of distinguishability. We quantify the effect of distinguishability on quantum metrology experiments, and report results of an experiment to verify that two- and four-photon states containing partially-distinguishable photons can achieve quantum-enhanced sensitivity with low-visibility quantum interference. This demonstrates that sources producing photons with mixed spectral states can be readily utilized for quantum metrology.

quant-ph↗

arXiv2016

Demonstrating an absolute quantum advantage in direct absorption measurement

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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