Force metrology using quantum correlations of light due to a room-temperature mechanical oscillator

We report on the observation of quantum correlations developed in a light beam that has interacted with a room-temperature nanomechanical oscillator. The vacuum fluctuations of the light drive the mechanical oscillator via the radiation pressure interaction, so that the phase of the transmitted light carries imprints of its own amplitude. We detect these subtle correlations, at the 5% level, using broadband measurements of the transmitted light in a homodyne detector tuned close to the amplitude quadrature. We also show how such correlations can be used for quantum-enhanced force metrology at room-temperature.