QUANTUM CORRELATIONS IN DUAL QUANTUM MEASUREMENTS

We analyze the quantum measurement properties of dual non-degenerate p arametric amplifers in the twin-beam configuration, in the cascaded ba ck-action-evasion configuration, and in Kerr-type photon-number quantu m non-demolition measurements. It is found that Einstein-Podolsky-Rose n correlations can be obtained between the quadrature components of an idler mode and the sum of the readout of two signal modes. Furthermor e, we discuss dual-mode quantum non-demolition measurements on the com bination of two light modes, and the generation of number-state entang lement.