Continuous-Variable Nonclassicality Detection under Coarse-Grained Measurement

TL;DR

This paper demonstrates that coarse-grained measurements, often considered imperfect, can effectively detect nonclassicality in continuous-variable quantum states, surpassing traditional methods in sensitivity and significance.

Contribution

The study experimentally shows that coarse-grained measurements can outperform fine-grained ones in detecting nonclassicality, offering a practical approach for quantum technology applications.

Findings

Coarse-grained measurement detects nonclassicality beyond variance criteria.

It exhibits stronger statistical significance than high-order moments methods.

Effective for both Gaussian and non-Gaussian states.

Abstract

Coarse graining is a common imperfection of realistic quantum measurement, obstructing the direct observation of quantum features. Under highly coarse-grained measurement, we experimentally detect the continuous-variable nonclassicality of both Gaussian and non-Gaussian states. Remarkably, we find that this coarse-grained measurement outperforms the conventional fine-grained measurement for nonclassicality detection: it detects nonclassicality beyond the reach of the variance criterion, and furthermore, it exhibits stronger statistical significance than the high-order moments method. Our work shows the usefulness of coarse-grained measurement by providing a reliable and efficient way of nonclassicality detection for quantum technologies.