Violation of the Cauchy-Schwarz Inequality in the Macroscopic Regime

Abstract

We have observed a violation of the Cauchy-Schwarz inequality in the macroscopic regime by more than 8 standard deviations. The violation has been obtained while filtering out only the low frequency noise of the quantum-correlated beams that results from the technical noise of the laser used to generate them. We use bright intensity-difference squeezed beams produced by four-wave mixing as the source of the correlated fields. We also demonstrate that squeezing does not necessarily imply a violation of the Cauchy-Schwarz inequality.

5 pages, 4 figures

References in corpus (2)

• Strong relative intensity squeezing by 4-wave mixing in Rb vapor
• Ultraslow propagation of matched pulses by four-wave mixing in an atomic vapor

Cited by in corpus (9)

• Violation of the Cauchy-Schwarz inequality with matter waves
• Sub-Poissonian number differences in four-wave mixing of matter waves
• Violation of classical inequalities by photon frequency-filtering
• Hot atomic vapors for nonlinear and quantum optics
• Quantum noise correlations of an optical parametric oscillator based on a non-degenerate four wave mixing process in hot alkali atoms
• All-optical mode conversion via spatially-multimode four-wave mixing
• A matter wave Rarity-Tapster interferometer to demonstrate non-locality
• Transmission Estimation at the Fundamental Quantum Cramér-Rao Bound with Macroscopic Quantum Light
• Observation of a Multimode Displaced Squeezed State in High-Harmonic Generation