Inseparability Criterion for Continuous Variable Systems

Phys Rev Lett. 2000 Mar 20;84(12):2722-5. doi: 10.1103/PhysRevLett.84.2722.


An inseparability criterion based on the total variance of a pair of Einstein-Podolsky-Rosen type operators is proposed for continuous variable systems. The criterion provides a sufficient condition for entanglement of any two-party continuous variable states. Furthermore, for all Gaussian states, this criterion turns out to be a necessary and sufficient condition for inseparability.