Entanglement Purification of Gaussian Continuous Variable Quantum States
L.-M. Duan, G. Giedke, J. I. Cirac, P. Zoller · Physical Review Letters · 2000
We describe an entanglement purification protocol to generate maximally entangled states with high efficiencies from two-mode squeezed states or from mixed Gaussian continuous entangled states. The protocol relies on a local quantum nondemolition measurement of the total excitation number of several continuous variable entangled pairs. We propose an optical scheme to do this kind of measurement using cavity enhanced cross-Kerr interactions.