P. Verlot

Observation of Back-Action Noise Cancellation in Interferometric and Weak Force Measurements

We experimentally demonstrate a cancellation of back-action noise in optical measurements. Back-action cancellation was first proposed within the framework of gravitational-wave detection by dual resonators as a way to drastically improve their sensitivity. We have developed an experiment based on a high-finesse Fabry-Perot cavity to study radiation-pressure effects in ultrasensitive displacement measurements. Using an intensity-modulated intracavity field to mimic the quantum radiation-pressure noise, we report the first observation of back-action cancellation due to a coherent mechanical response of the mirrors in the cavity to the radiation-pressure noise. We have observed a sensitivity improvement by a factor larger than 20 both in displacement and weak-force measurements.

Backaction amplification and quantum limits in optomechanical measurements.

Optical interferometry is by far the most sensitive displacement measurement technique available, with sensitivities at the 10(-20) m/square root(Hz) level in the large-scale gravitational-wave interferometers currently in operation. Second-generation interferometers will experience a tenfold improvement in sensitivity and be mainly limited by quantum noise, close to the standard quantum limit (SQL), once considered as the ultimate displacement sensitivity achievable by interferometry. In this Letter, we experimentally demonstrate one of the techniques envisioned to go beyond the SQL: amplification of a signal by radiation-pressure backaction in a detuned cavity.

Quantum optomechanical correlations induced by radiation pressure between light and mirrors

Radiation pressure exerted by light in interferometric measurements is responsible for displacements of mirrors which appear as an additional back-action noise and limit the sensitivity of the measurement. We experimentally study these effects by monitoring in a very high-finesse optical cavity the displacements of a mirror with a sensitivity at the 10-20m/√Hz level. This unique sensitivity is a step towards the first observation of the fundamental quantum effects of radiation pressure and the resulting standard quantum limit in interferometric measurements. Our experiment may become a powerful facility to test quantum noise reduction schemes, and we already have demonstrated radiation-pressure induced correlations between two optical beams sent into the same moving mirror cavity. Our scheme can be extended down to the quantum level and has applications both in high-sensitivity measurements and in quantum optics.

Optomecanical correlations and sensitivity improvement by backaction amplification

We present our experiments devoted to the observation of quantum radiation-pressure effects and to quantum-noise reduction schemes. We have demonstrated optomechanical correlations between two independent laser beams, and a backaction amplification scheme.

Observation of radiation-pressure effects and back-action cancellation in interferometric measurements

Radiation pressure exerted by light in interferometric measurements is responsible for displacements of mirrors which appear as an additional back-action noise and limit the sensitivity of the measurement. We experimentally study these effects by monitoring in a very highfinesse optical cavity the displacements of a mirror with a sensitivity at the 10-20 m/√Hz level. This unique sensitivity is a step towards the first observation of the fundamental quantum effects of radiation pressure and the resulting standard quantum limit in interferometric measurements. Our experiment may become a powerful facility to test quantum noise reduction schemes, and we already report the first experimental demonstration of a back-action noise cancellation. Using a classical radiation-pressure noise to mimic the quantum noise of light, we have observed a drastic improvement of sensitivity both in position and force measurements.

Radiation-pressure effects and back-action cancellation in interferometric measurements

We report the first experimental demonstration of back-action cancellation of radiation pressure, with a setup based upon a high-finesse optical cavity with movable mirrors. Further improvement will allow to probe quantum effects of radiation pressure.