A Quantum Enhanced Gravitational Wave Detector

Advanced gravitational wave detectors, currently under construction, are expected to be limited by quantum optical noise in much of their detection band; using squeezed states of light is the most promising way to further improve their sensitivity. I describe an experiment where squeezed light injection was used to reduce the shot-noise limit in the LIGO 4-km-long interferometric detector, leading to the best broadband sensitivity achieved to date in a gravitational wave detector; I will also present results on my investigation of potential noise sources and limits for detected squeezing.