Observation of twin beam correlations and quadrature entanglement by frequency doubling in a two-port resonatorO.-K. Lim, B. Boland and M. Saffman
Department of Physics, University of Wisconsin - 1150 University Avenue, Madison, WI 53706, USA
received 12 February 2007; accepted in final form 10 April 2007; published May 2007
published online 9 May 2007
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.
03.67.Mn - Entanglement production, characterization and manipulation .
42.50.Dv - Nonclassical states of the electromagnetic field, including entangled photon states; quantum state engineering and measurements .
42.65.Ky - Frequency conversion; harmonic generation, including higher-order harmonic generation .
© Europhysics Letters Association 2007