Observation of the Thermal Fluctuations of a Gravitational-Wave Detector

Abstract

We report operation of apparatus to measure the Fourier transform of the Riemann curvature tensor at sensitivity limited by the thermal fluctuations. The gravitational interaction drives a mechanical system which in turn is coupled to the electromagnetic field. Strains as small as a few parts in ${10}^{16}$ are observable for a compressional mode of a large cylinder.