Squeezed light in present and future GW observatories · Alexander Khalaidovski Squeezed light in...
Transcript of 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
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ET sensitivity curves
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Coherent state
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Michelson interferometer – bright port
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Vacuum state (0-point fluctuations of EM field)
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Origin of the quantum noise
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Squeezed vacuum state
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Injecting squeezed vacuum
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How to do?
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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
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squeezed-light lasers for
GW observatories
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The GEO 600 squeezed-light laser
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LIGO-H1 squeezed-light laser
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Requirements
Squeezing in earth-bound GW detection band
(10 Hz – 10 kHz)
Stable control scheme
(allowing for long-term, independent operation)
Strong squeezing
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Squeezing spectrum
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Loss sources
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Loss sources
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Squeezing available for injection
maximal directly observed squeezing: 9.6 dB
up to 11.5 dB available for injection
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Squeezing spectrum
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Available well below 10 Hz
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Long-term stability (automated exp. control)
Khalaidovski et al., Class. Quantum Grav. 29 (2012) 075001
duty cycle: 99.93 %
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squeezed-light lasers are ready
the message concerning squeezed-light lasers
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State-of-the-art
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squeezing in GW observatories today
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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
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H. Grote @ March LVC Meeting (MIT)
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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
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the future
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Einstein Telescope
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Einstein Telescope
Goal: 10 dB squeezing detected
total allowed optical loss: 10 %
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Loss sources
- Faraday isolators
- polarization optics
propagation loss, especially:
escape efficiency of the squeezed light source
detection loss
non-perfect mode-matching
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Squeezing injection
ˆ X 1
ˆ X 2
Quantum noises
Shot-noise
dominated
Radiation
pressure noise
dominated
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Filter cavities
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Remaining challenges
very low round-trip loss required
deviation from design parameters
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Filter cavities
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Remaining challenges
very low round-trip loss required
mode-matching
deviation from design parameters tunable loss
filter cavity length control scheme (detuned from resonance!)
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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
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thank you
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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
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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)
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Control scheme for audio-frequency squeezing
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Origin of the quantum noise
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Loss sources
r=T
T + L
escape efficiency of the squeezed light source
Absorption
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Loss sources
escape efficiency of the squeezed light source
propagation loss (Faraday isolator, pol. optics, coatings)
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Loss sources
escape efficiency of the squeezed light source
propagation loss
detection loss (photo diodes, homodyne fringe visibility)
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Loss sources
escape efficiency of the squeezed light source
propagation loss
detection loss
< total loss during characterization: 10.5 %
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how much squeezing can we inject in
GEO 600?
Injection of squeezed light
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Sensitivity to optical loss
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Sensitivity to optical loss
maximal squeezing: 9.6 dB
total identified loss: 10.5 %
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Implementation in GEO 600
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Optical loss
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Expected squeezing impact
due to loss from injection to detection
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near future
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Next steps at GEO HF
• OMC
• propagation
reducing losses
• mode-matching } ca. 22 %
seem feasible
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Goal
6 dB detected squeezing
Factor 2 sensitivity improvement