Progress toward squeeze injection in Enhanced LIGO Gravitational wave detectors Squeeze-enhanced AdLIGO Nergis Mavalvala @ LVC, September 2009 LIGO-G0900849-00

Advanced LIGO with squeeze injection Radiation pressure Shot noise Power higher by 4x OR 6 dB squeeze injection

Quantum Noise in an Interferometer Radiation pressure noise Quantum fluctuations exert fluctuating force  mirror displacement X1 X2 Laser X1 X2 Shot noise limited  (number of photons)1/2 Arbitrarily below shot noise X1 X2 X1 X2 Vacuum fluctuations Squeezed vacuum

Squeezed state generation

How to squeeze? My favorite way A tight hug

Squeezing injection Second harmonic generator (SHG) Laser Convert 1064 nm  532 nm with ~50% efficiency Optical parametric oscillator (OPO) Few 100 mW pump field (532 nm) correlates upper and lower quantum sidebands around carrier (1064 nm)  squeezing Balanced homodyne detector Beat local oscillator at 1064nm with squeezed field Laser IFO OPO Faraday rotator ASPD SHG

Squeezed injection in LIGO (after S6)

Goals of H1 test Inject 6 dB of squeezing into the antisymmetric (AS) port of H1 Measure 3 dB of improved SNR at frequencies where interferometer is shot noise limited Ensure that no deleterious effects at all other frequencies in detection band Low noise performance test is remaining critical step to implementation in Advanced LIGO

The H1 squeezer components Initial LIGO 10 W MOPA pumps… AEI-designed SHG  300 to 500 mW of 532 nm (green) ANU-designed and built traveling wave OPO LIGO-designed and built electronics Integration and testing at MIT and LHO

Control System Interferometer S0 Fiber (PSL) Faraday S4 Laser 0 SHG Homodyne Detector Faraday S4 Laser 0 SHG OPO S3 S1 S5 S2 OMC Auxiliary Laser 1 AS Port Squeezer DC 10

Servo Model S0 Frequency lock Laser 0 to PSL using FSS S1  Frequency lock Laser 1 (auxiliary ) to Laser 0 using FSS S2  Phase lock Laser 1 to green light using feedback to PZT & Laser 1 additive offset S3  Phase lock squeeze angle to AS port light using feedback to PZT & Laser 0 additive offset (LO lock) S4  Lock SHG to Laser 0 with PDH to cavity PZT S5  Lock OPO to green with PDH to cavity PZT

Simulink Model LIGO-T0900325-v1 Sigg, Dwyer et al.

Fiber Stabilization not needed Servo Model Servo Description Bandwidth Crossover Laser 0 500kHz 10kHz 1 Laser 1 2 Coherent field 100kHz ~2kHz 3 Local oscillator 4 SHG length ~1kHz — 5 OPO length Fiber Stabilization not needed Laser 0 is frequency locked to main interferometer laser (PSL) and phase locked to AS port light

Noise couplings

Noise Model Highlights Acoustic couplings Direct back scattering under control Requirement OMC has Require second in-vacuum Faraday OPO ring topology is very helpful Motion of scatterer Backscatter reflectivity

Noise Model Highlights Phase noise requirement < 50 mrad rms Squeeze angle deviation Remaining RF sidebands transmitted through OMC are important Detected quadrature Anti-squeeze projection PCR is the total carrier after OMC  10 mW for ELIGO PCD is carrier due to contrast defect  0.4 mW (rest is from length offset) The total amplitude of the phase modulation is related to the total power in the RF sidebands and the amount of carrier power that is the same phase as the contrast defect. Total rms phase fluctuations are sqrt[TSB*PSB*PCD/PCR^2] Phase Noise (°) Squeeze angle deviation PCR/PCD

Noise Model Highlights Other noise couplings Laser frequency noise not important due to large servo bandwidth (500 kHz) Path length variations not important due to large servo bandwidth (few kHz) Shot noise: 1 mW per detector should be enough OPO length fluctuations are not suppressed by Local Oscillator (LO) servo

ANU Traveling Wave OPO 150 mm 200 mm PZT Actuator Squeezing Out Oven/ Temperature Sensor Crystal Squeezing Out Pump light In PZT Actuator 150 mm 200 mm 18

ANU OPO Squeezing Performance Electronics Mains harmonics Cross coupling from Coherent Lock Quantum noise Electronic Noise? Lab environment Acoustic Noise 6dB Observed squeezing 8dB Inferred squeezing H1 Squeezer Status 19

Schedule and Planning Reviewed, approved and funded (08/2009) ANU will continue on development of OPO On track for Spring 2010 delivery MIT will continue with SHG & laser locking On track to begin integration with OPO in Spring 2010 Electronics production at LHO moving forward RF, PDs, TTFFS and length servos (common mode board) to arrive at MIT December 2009 Planning for installation in Feb. 2011 Depends on Advanced LIGO commissioning sequence and S6

Highlights and summary Outstanding team assembled Graduate students Sheila Dwyer (MIT), Sheon Chua (ANU) and Michael Stefsky (ANU), Alexander Khalaidovski (AEI) Led by Daniel Sigg at LHO Impressive progress on OPO development at ANU 6 dB of squeezing observed Traveling wave bowtie design works Laser, optical table and clean room installed at MIT AEI loaner SHG at MIT producing green Entering optimization phase In the process of building our own (copy of AEI design) Noise model and simulation done Electronics design done for RF distribution Shared with advanced LIGO

The End GW Detector Laser Faraday isolator Homodyne Detector GW Signal SHG Faraday isolator OPO Homodyne Detector Squeeze Source GW Signal