1. Ponderomotive amplifier to reduce shot noise GWADW @ Kyoto May. 2010 Kentaro Somiya 1 and Yanbei Chen 2 Waseda Inst. for Adv. Study 1 and Caltech 2

2. High-freq sensitivity of GWD RSE High Finesse anti-reso reso SR gain could be higher if the arms were shorter. Optical-bar regime by Braginsky and Khalili SRM PRM

3. Optical-bar regime locked by opt spring local-readout (high SRG) ITMETM Dual Recycling instead of PR+RSE (f<spring) Signal enhancement at spring frequency High power required to increase spring frequency [Braginsky 98][Rehbein 07] local-readout interpretation

4. Optical lever [Khalili 02] [Danilishin 06] Reasonable power on the small mirrors Chen-type optical lever is rather an amplifier GW signal converts to radiation pressure in PA interpretation more signal less power [Chen 03] Ponderomotive amplifier locked free 40kg 4km 1g 1m

5. Ponderomotive amplifier 40kg 4km 1g 1m sig (phase) sig (amp) pump (amp) RP sig (phase) RP sig (amp) sig (phase) carrier (amp) GW signal coupled with pump RP signal reenters coupled with carrier Vacuum enters from the pick-off Optimized combination of the two outputs in the best quadrature

6. Ponderomotive amplifier A B I1I1 I2I2 A= B= ………… I 1 x … + I 2 x … + … maximize SNR I 2 x [vacuum + signal + disp-noise] GWD Amp Shot noise Signal 4 T cos  I 1 (1-T)  : detune phase T : transmittance of input coupler input coupler If I 2 -term is dominant… Signal is amplified and SNR increases

7. Sensitivity gain GWD L=4km, m=40kg, I 0 =1kW, F=120 PA L=10cm, m=1g, I 0 =100W, F=6000 IC R=81%,  =1.5rad Big reduction of shot noise up to kHz Strong against PD losses Power on PA might be a bit high…

8. PA displacement noise The small-mirror IFO will be noisy The motion is suppressed by the optical spring

9. Sensitivity curve Not yet fully optimized Good sensitivity with low power PA noise limits the sensitivity at high freq

10. PBS Single-path ponderomotive amplifier I1I1 I2I2 GWD Amp vacuum (TF and QN of DRSE) It turns out this one doesn’t work Signal and noise increases at once Recall the situation with detuned RSE…

11. Summary Ponderomotive amplifier based on optical lever Reduction of shot noise Strong against optical losses PA displacement noise is suppressed by spring Possible combinations: LIGO + MIT 1g IFO Virgo + LKB micro-mirror GEO + membrane TAMA + NAO 20mg IFO… etc.

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14. Transfer function of signal/noise