Observation of twin beam correlations and quadrature entanglement by frequency doubling in a two-port resonator

Department of Physics, University of Wisconsin - 1150 University Avenue, Madison, WI 53706, USA

Received: 12 February 2007
Accepted: 10 April 2007

Abstract

We demonstrate production of short wavelength beams with nonclassical intensity correlations and quadrature entanglement using second harmonic generation in a nonlinear resonator with two output ports. The two output beams at the harmonic frequency have no direct interaction but are both nonlinearly coupled to a common pump beam. The nonlinear coupling produces amplitude and phase correlations between the beams which results in quadrature entanglement. The output beams at are shown to exhibit 0.6 dB of amplitude quadrature squeezing, 0.9 dB of nonclassical intensity correlations, and of entanglement using about 30 mW of pump power.