Experimental demonstration of a gravitational wave detector configuration below the shot noise limit

Abstract

Unprecedented sensitivity of measurement is required to detect gravitational waves. Although the first generation of interferometric gravitational wave detectors are the most sensitive devices ever built, it is expected they will not be sensitive enough to regularly detect gravitational waves. The precision of the optical measurement used in gravitational wave detectors is ultimately limited by the quantum mechanical fluctuations of the light, called quantumnoise. The first generation of interferometric gravitational wave detectors have reached the quantum noise limit at some frequencies. Second generation interferometric gravitational wave detectors are expected to be limited by quantum noise across most of the detection frequency band. This thesis presents the first experimental demonstration of a gravitational wave detector configuration with sensitivity below the quantum noise limit. The configuration demonstrated is a power recycled Michelson interferometer with the addition of squeezed light. The control of the configuration and the method for injection of squeezed light are compatible with current gravitational wave detectors. A model for the configuration is derived using linearized operators for the optical fields. The results obtained demonstrate the improvement below the shot noise limit using squeezed light, and the interaction of power recycling with squeezed light is investigated. The predictions made using the model show excellent agrement with the experimental results. The entire system maintains stable lock for long periods.