QUANTUM-NONDEMOLITION SCHEMES TO MEASURE QUADRATURE PHASES USING INTRACAVITY HARMONIC-GENERATION

In this paper, we present a theoretical investigation into the quantum -nondemolition (QND) properties of a system which utilizes intracavity harmonic generation. It is found that a nearly ideal QND measurement of the amplitude of a signal can be performed using second-harmonic ge neration, while subharmonic generation can be utilized to give a nearl y ideal QND measurement of a phase. The results show a significant imp rovement over the QND properties of other systems studied previously a nd should be accessible to experiment.