squeezed light in present and future gw observatories · alexander khalaidovski squeezed light in...

Squeezed light in present and future GW observatories Alexander Khalaidovski 1

Squeezed light

in present and future GW observatories

Alexander Khalaidovski for the AEI Quantum Interferometry group

(Roman Schnabel)

13th Marcel Grossman Meeting – MG13 – Stockholm University

Albert Einstein Institute

Max Planck Institute for Gravitational Physics

Institute for Gravitational Physics of the Leibniz University Hannover

http://www.qi.aei-hannover.de


ET sensitivity curves


Coherent state


Michelson interferometer – bright port


Vacuum state (0-point fluctuations of EM field)


Origin of the quantum noise


Squeezed vacuum state


Injecting squeezed vacuum


How to do?


Generation of squeezing

LiNbO3 or

PPKTP

BASED ON OPTICAL PARAMETRIC AMPLIFICATION (OPA)

Squeezed field:

Pump field: 532 nm cw

1064 nm cw

For GW observatories


squeezed-light lasers for

GW observatories


The GEO 600 squeezed-light laser


LIGO-H1 squeezed-light laser


Requirements

Squeezing in earth-bound GW detection band

(10 Hz – 10 kHz)

Stable control scheme

(allowing for long-term, independent operation)

Strong squeezing


Squeezing spectrum


Loss sources


Squeezing available for injection

maximal directly observed squeezing: 9.6 dB

up to 11.5 dB available for injection


Squeezing spectrum


Available well below 10 Hz


Long-term stability (automated exp. control)

Khalaidovski et al., Class. Quantum Grav. 29 (2012) 075001

duty cycle: 99.93 %


squeezed-light lasers are ready

the message concerning squeezed-light lasers


State-of-the-art


squeezing in GW observatories today


Squeezing-improved GEO 600 sensitivity

The LIGO Scientific Collaboration, Nature Phys. 7 (2011) 962-965

Factor 1.5

sensitivity improvement

Up to 3.5 dB

detected squeezing


H. Grote @ March LVC Meeting (MIT)


H1 with squeezed light

• 2.25 dB squeezing

enhancement

• squeezing

observable down to

100 Hz

• no noise added at

lower frequencies

• inspiral range

improved by 1 Mpc

Courtesy Lisa Barsotti for the LIGO Scientific Collaboration


the future


Einstein Telescope


Einstein Telescope

Goal: 10 dB squeezing detected

total allowed optical loss: 10 %


Loss sources

- Faraday isolators

- polarization optics

propagation loss, especially:

escape efficiency of the squeezed light source

detection loss

non-perfect mode-matching


Squeezing injection

ˆ X 1

ˆ X 2

Quantum noises

Shot-noise

dominated

Radiation

pressure noise

dominated


Filter cavities


Remaining challenges

very low round-trip loss required

deviation from design parameters


Filter cavities


Remaining challenges

very low round-trip loss required

mode-matching

deviation from design parameters tunable loss

filter cavity length control scheme (detuned from resonance!)


Conclusions

Squeezing is already used in the first detector generation (GEO 600, H1)

Squeezing will become a ‚standard‘ technique in future detector

Optical loss is squeezings‘ biggest enemy!!!

- better AR coatings

- lower crystal absorption

- lower propagation loss

(mainly polarization optics)

} higher squeezing contribution

generations


thank you


Experimental layout (scaled to reality)

• Breadboard: 113x135 cm

• Main Laser: InnoLight Mephisto

> 120 opt. components

• Aux. Lasers: Mephisto OEM

total weight ≈ 120 kg

• Optics: ATF (superpolished)

• Nonlinear medium: PPKTP

• Beam height: 50mm

• Compact design


LIGO-SQUEEZER

• generally similar to AEI device

• main differences:

- „off-the shelf“ optics used

- requires more space, beam height 4´´

- no cleanroom environment

higher stray light contribution

- no fast data acquisition channels

- SHG design

- doubly-resonant (1064 nm and 532 nm)

- bow-tie configuration

additional 42 dB isolation

- LO beam from PSL via fiber

excess phase noise, no MC

• AEI contributions

- balanced homodyne detector

(- control scheme)


Control scheme for audio-frequency squeezing


Origin of the quantum noise


Loss sources

r=T

T + L


Absorption


Loss sources


propagation loss (Faraday isolator, pol. optics, coatings)


Loss sources


propagation loss

detection loss (photo diodes, homodyne fringe visibility)


Loss sources


propagation loss

detection loss

< total loss during characterization: 10.5 %


how much squeezing can we inject in

GEO 600?

Injection of squeezed light


Sensitivity to optical loss


Sensitivity to optical loss

maximal squeezing: 9.6 dB

total identified loss: 10.5 %


Implementation in GEO 600


Optical loss


Expected squeezing impact

due to loss from injection to detection


near future


Next steps at GEO HF

• OMC

• propagation

reducing losses

• mode-matching } ca. 22 %

seem feasible


Goal

6 dB detected squeezing

Factor 2 sensitivity improvement

squeezed light in present and future gw observatories · alexander khalaidovski squeezed light in...

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