Extracting Spatial Information from Noise Measurements of Multi-Spatial-Mode Quantum States

TL;DR

This paper demonstrates how spatial quantum correlations in twin beams can be used to extract mask shape information with enhanced sensitivity, surpassing classical limits, especially in low-photon regimes, using noise measurements via homodyne detection.

Contribution

It introduces a method leveraging quantum correlations in twin beams for spatial information extraction, showing sensitivity enhancement over classical states in low-photon regimes.

Findings

Quantum states improve shape estimation sensitivity.

Quantum correlations provide non-classical enhancement.

Method effective in low-photon detection regimes.

Abstract

We show that it is possible to use the spatial quantum correlations present in twin beams to extract information about the shape of a mask in the path of one of the beams. The scheme, based on noise measurements through homodyne detection, is useful in the regime where the number of photons is low enough that direct detection with a photodiode is difficult but high enough that photon counting is not an option. We find that under some conditions the use of quantum states of light leads to an enhancement of the sensitivity in the estimation of the shape of the mask over what can be achieved with a classical state with equivalent properties (mean photon flux and noise properties). In addition, we show that the level of enhancement that is obtained is a result of the quantum correlations and cannot be explained with only classical correlations.