Continuous-Variable Spatial Entanglement for Bright Optical Beams
  A light beam is said to be position squeezed if its position can be determined to an accuracy beyond the standard quantum limit. We identify the position and momentum observables for bright optical beams and show that position and momentum entanglement can be generated by interfering two position, or momentum, squeezed beams on a beam splitter. The position and momentum measurements of these beams can be performed using a homodyne detector with local oscillator of an appropriate transverse beam profile. We compare this form of spatial entanglement with split detection-based spatial entanglement. 
Magnus T.L. Hsu, Warwick P. Bowen, Nicolas Treps and Ping Koy Lam