Experimental evaluation of the non-classical relation between measurement errors using entangled photon pairs as a probe

TL;DR

This paper experimentally investigates the non-classical relationship between measurement errors in joint polarization measurements using entangled photons, revealing inherently quantum correlations that defy classical explanation.

Contribution

It introduces a novel method to evaluate the non-classical relation between measurement errors in non-commuting observables using entangled photon pairs.

Findings

Squared visibilities of local measurements are obtained directly from data.

The squared product visibility is negative, indicating non-classical correlations.

Experimental results demonstrate the quantum nature of measurement error relations.

Abstract

We have experimentally evaluated the non-classical relation between measurement errors in a joint measurement of two non-commuting polarizations by using entangled photon pairs as a probe. The joint measurement was realized by filtering polarization directions that are sensitive to both of the two target polarizations and the same filtering procedures were applied independently to the two photons of an entangled pair. Since the statistically independent measurement errors of two identical measurements performed on entangled pairs will reduce an overall visibility of the correlation by the square of the local visibilities, the squared visibilities of the local measurements can be obtained directly from the measurement data. We apply this method to determine the visibility of the correlation between the products of the two non-commuting polarizations, a characteristic of the measurement errors that can not be obtained locally since there is no self-adjoint operator that describes this product of measurement outcomes as a single photon observable. The experimental results clearly show that the square of the product visibility is negative, indicating the non-classical nature of the statistical relation between the measurement errors of non-commuting polarizations.