Radiation pressure effects in interferometric measurements

Transcription

1 Laboratoire Kastler Brossel, Paris Radiation pressure effects in interferometric measurements A. Heidmann M. Pinard J.-M. Courty P.-F. Cohadon T. Briant O. Arcizet T. Caniard C. Molinelli P. Verlot

2 Quantum noises in interferometers Two conjugate quantum noises: Laser noise (shot noise) Mirror motion due to radiation pressure Quantum limits in interferometric measurements

3 Quantum noises in advanced configurations Advanced Virgo sensitivity curve, M. Punturo (2004)

4 Quantum noise reduction Many proposals to reduce quantum noises: Injection of squeezed states QND detection Dynamical effects with detuned interferometer Buonanno et al, PRD (2001) Quantum locking of mirrors Courty et al, PRL (2003)

5 Study of quantum noises in interferometers Application of quantum optics techniques to GW interferometers Adaptation of squeezing (low frequency, wideband effects) Constraints on the interferometer (losses, ) Objectives: Efficient and robust schemes Kimble et al, PRD (2002) Experimental tests of quantum noises

6 Experimental tests of quantum noises Injection of squeezing in an interferometer: McKenzie et al, PRL (2002) In dual-recycled interferometer: R. Schnabel et al, PRL (2005) No demonstration of quantum effects of radiation pressure!

7 Experimental test of radiation pressure Very sensitive optomechanical sensor based on a high-finesse cavity Current finesse: Model system to study the coupling between light and moving mirrors Current sensitivity: Dynamical effects of radiation pressure (parametric instability, optical damping) Quantum noises and noise reduction schemes

8 Quantum noises in optomechanical sensor Compromise between phase and radiation pressure noises Standard quantum limit Mass: Cavity: Cryostat:

9 Constraints on the moving mirror Elimination of technical noises: No pendular motion Large radiation pressure effects: Reduction of thermal noise: Mirrors coated on micro-resonators Working in vacuum and at low temperature

10 Micro-resonators Micro-fabrication at ESIEE Optical coating at LMA Optical metrology at ESPCI

11 Micro-mirror and cavity Precise translation mechanism preserving the parallelism

12 Experimental setup Highly stable YAG laser source High finesse cavity in vacuum and thermally stabilized Pound-Drever-Hall detection: frequency locking displacement sensing Possibility to apply an electrostatic force:

13 Thermal noise spectrum at 300 K Observation of sharp and high mechanical resonances Sensitivity: O. Arcizet et al, PRL 97, (2006)

14 Optomechanical characterization of a mode Thermal noise - modulation Vibration profile

15 Radiation pressure and mirror dynamics Cavity detuning induces a binding or repulsive radiation pressure force Optical spring, bistability Cavity storage time comparable to mechanical oscillation period Optical damping Cooling or heating of the mirror Parametric instabilities

16 Optical cooling Observation of the dynamics on the thermal noise Negative detunings Positive detunings O. Arcizet et al, Nature 444, 71 (2006)

17 Optical cooling Observation of the dynamics on the thermal noise Effective temperature ranging from 10 K to 2000 K O. Arcizet et al, Nature 444, 71 (2006)

18 Optical damping Optical damping for different incident light powers 3.2 mw 2.2 mw 1.6 mw 0.9 mw 0.5 mw Theoretical curves: optical damping is only due to radiation pressure

19 Parametric instability Airy peaks in ϕ P plane: Spontaneous oscillation in the unstable domain with amplitude ~ 10 pm

20 Conclusion Low-loss mirror coated on a Si micro-resonator High-sensitivity displacement measurement First observation of dynamical effects of radiation pressure: optical spring, optical damping and parametric instability Next objectives : Low temperature operation Observation of quantum effects of radiation pressure