einstein gravitational wave telescope which optical topologies are suitable for et? andreas freise...
TRANSCRIPT
Einstein gravitational wave Telescope
Which optical topologies are suitable for ET?
Andreas Freisefor the ET WG3 working group
15.07.2009 MG12 Paris
A. Freise A Freise MG12 15/07/2009 Slide 2
How will ET look like?
How many interferometers per site?
What type of interferometer do we need?
Investigating new topologies
Practical considerations
Overview
The working group WP3 must select an interferometer topology for ET, we will present examples from the ongoing research:
A. Freise A Freise MG12 15/07/2009 Slide 3
What will be the shape of ET?
A. Freise A Freise MG12 15/07/2009 Slide 4
LL
45°
Fully resolve polarizations
5 end caverns
4×L long tunnels
45° stream generated by virtual interferometry
Null stream
Redundancy
7 end caverns
6×L long tunnels
60°
L’=L/sin(60°)=1.15×L
Fully resolve polarizations by virtual interferometry
Null stream
Redundancy
3 end caverns
3.45×L long tunnels L
Equivalent to
[Ruediger et al (1985), Freise et al, Class. Quantum Grav. 26 (2009)]
A. Freise A Freise MG12 15/07/2009 Slide 5
Multiple Interferometers: the Triangle
Both solutions have an integrated tunnel length of 30 km, they can resolve both GW polarisations, feature redundant interferometers and have equivalent sensitivity.
The triangle reduces the number of end stations and the enclosed area!
[P Jaranowski et al, Phys Rev D 58 1998]
A. Freise A Freise MG12 15/07/2009 Slide 6
Today's Michelsons in a Triangle
[S Hild]
A. Freise A Freise MG12 15/07/2009 Slide 7
How Many Interferometers Arms per Tunnel?
Picture by Jason Bacon used under a Creative Commons License
Rüdiger, Aspen 2007
A. Freise A Freise MG12 15/07/2009 Slide 8
Multiple Interferometers: a Xylophone
Low power (no thermal effects), cooled, long suspensions
High power, squeezing, LG modes, room temperature, `normal' suspensions
Maybe we can reach the target sensitivity easier by splitting the frequency range?
[S Hild et al, arXiv:0906.2655]
A. Freise A Freise MG12 15/07/2009 Slide 9
Reduction of Quantum Noise
[S. Hild et al, arxiv:0810.0604]
A. Freise A Freise MG12 15/07/2009 Slide 10
Quantum Noise Reduction
Optimised SR
[H. Rehbein und H. Mueller-Ebhardt, ET note ET-010-09 2009]
[S Chelkowski]
A. Freise A Freise MG12 15/07/2009 Slide 11
Quantum Noise Reduction
10dB frequency-dependentsqueezing
[H. Rehbein und H. Mueller-Ebhardt, ET note ET-010-09 2009]
[S Chelkowski]
A. Freise A Freise MG12 15/07/2009 Slide 12
Quantum Noise Reduction
Variational output and10 dB squeezing
[H. Rehbein und H. Mueller-Ebhardt, ET note ET-010-09 2009]
A. Freise A Freise MG12 15/07/2009 Slide 13
Quantum Noise Reduction
Sagnac with SR, variationaloutput and 10dB squeezing
[H. Rehbein und H. Mueller-Ebhardt, ET note ET-010-09 2009]
[S Chelkowski]
A. Freise A Freise MG12 15/07/2009 Slide 14
Several QND topologies seem feasible: Micheslon with SR, variational output, squeezing Sagnac or Mach Zehnder Interferometer with SR, … Optical bars, optical levers, double optical spring, …
All can be build using the L-shape form factor!
QND Topologies
Optical Lever
A. Freise A Freise MG12 15/07/2009 Slide 15
Additional noise couplings: For Example: The Sagnac topology
Non-zero area Sagnac Near-zero area Sagnac
A. Freise A Freise MG12 15/07/2009 Slide 16
Sagnac effect in ET
Analysis involves two effects
1.Static effects due to Earth’s rotation
Much more sensitive than current Laser gyros
2.Noise couplings• Frequency noise• Seismic noise• Beam jitter noise
[S. Chelkowski, talk at WP3 meeting 01/2009]
A. Freise A Freise MG12 15/07/2009 Slide 17
Example: Seismic noise
Non-zero area Sagnac requirements on lateral mirror motion:
Zero area Sagnac requirements:
[S. Chelkowski, talk at WP3 meeting 01/2009]
A. Freise A Freise MG12 15/07/2009 Slide 18
Practical Considerations: Example, Beam Size
A. Freise A Freise MG12 15/07/2009 Slide 19
Interferometer topology selection will be driven by the quantum noise reduction scheme
All topologies can be build as an L-shape
We can assemble 3 L-shapes efficiently as a triangle
Multiple interferometers per site are beneficial for the sensitivity, yield redundancy and robust data analysis methods (null streams)
Technical details and noise couplings need to be investigated further before a topology can be selected
Conclusion
A. Freise A Freise MG12 15/07/2009 Slide 20
…end