  Entanglement drives nearly all proposed quantum information technologies. By
up-converting part of a 1550 nm two-mode squeezed vacuum state to 532 nm, we
demonstrate the generation of strong continuous-variable entanglement between
widely separated frequencies. Nonclassical correlations were observed in joint
quadrature measurements of the 1550 and 532 nm fields, showing a maximum noise
suppression 5.5 dB below vacuum. Our versatile technique combines strong
nonclassical correlations, large bandwidth, and in principle, the ability to
entangle the telecommunication wavelength of 1550 nm with any optical
wavelength.
