Violation of the Cauchy-Schwarz Inequality in the Macroscopic Regime

摘要

We have observed a violation of the Cauchy-Schwarz inequality in themacroscopic regime by more than 8 standard deviations. The violation has beenobtained while filtering out only the low frequency noise of thequantum-correlated beams that results from the technical noise of the laserused to generate them. We use bright intensity-difference squeezed beamsproduced by four-wave mixing as the source of the correlated fields. We alsodemonstrate that squeezing does not necessarily imply a violation of theCauchy-Schwarz inequality.