Experimental investigation of criteria for continuous variable entanglement

Phys Rev Lett. 2003 Jan 31;90(4):043601. doi: 10.1103/PhysRevLett.90.043601. Epub 2003 Jan 29.

Abstract

We generate a pair of entangled beams from the interference of two amplitude squeezed beams. The entanglement is quantified in terms of EPR paradox and inseparability criteria, with both results clearly beating the standard quantum limit. We experimentally analyze the effect of decoherence on each criterion and demonstrate qualitative differences. We also characterize the number of required and excess photons present in the entangled beams and provide contour plots of the efficacy of quantum information protocols in terms of these variables.