Holographic Noise in GEO600?

1. Holographic Noise in GEO600? Stefan Hild for the GEO600 team 16th ILIAS WG1 meeting, July 2008, Birmingham

2. Articles on Holographic Noise available on arXiv: arXiv:astro-ph/0703775v4 arXiv:0706.1999v2 arXiv:0709.0611v1 arXiv:0710.4153v2 arXiv:0806.0665v2 ILIAS WG1, March 2008

3. Published article on Holographic Noise ILIAS WG1, March 2008

4. Contents of this presentation • Attempt to explain: “What is holographic noise?” • Craig’s predictions • Points we (experimentalists) do not understand • Comparison of Craig’s prediction with noise measured in GEO600 • How to go on from here … ILIAS WG1, March 2008

5. Spacetime • Space time is not continuous, but quantized. • Assumption:smallest length is the Planck wavelength • This gives a fundamental limit for measurements ILIAS WG1, March 2008

6. Holographic principle • Some recent findings suggest that all information of a 3D world can be encoded in a 2D surface at Planck resolution. • Example: black hole theory suggest that the entropy scales proportional to its area (not its volume!) • Hypothesis: Quantum geometry (spacetime) has only 2+1 dimesions. ILIAS WG1, March 2008

7. Indeterminancy of transverse Positions • Angles are indeterminate at Planck scale: • Relative Transverse Positions are uncertain. Uncertainty increases at larger separation: ILIAS WG1, March 2008

8. Holographic shear noise PRD 77, 104031 ILIAS WG1, March 2008

9. Characteristic of a random walk Time series of a random walk PSD of random walk time series • The spectrum of a random walk is 1/f in ASD. ILIAS WG1, March 2008

10. Contents of this presentation • Attempt to explain: “What is holographic noise?” • Craig’s predictions • Points we (experimentalists) do not understand • Comparison of Craig’s prediction with noise measured in GEO600 • How to go on from here … ILIAS WG1, March 2008

11. Craigs Predictions from arXiv:0806.0665v2 • Zero-parameter estimates • GEO600: • LIGO: f < 550Hz f > 550Hz f < 150Hz f > 150Hz ILIAS WG1, March 2008

12. Contents of this presentation • Attempt to explain: “What is holographic noise?” • Craig’s predictions • Points we (experimentalists) do not understand • Comparison of Craig’s prediction with noise measured in GEO600 • How to go on from here … ILIAS WG1, March 2008

13. Points we (experimentalists) do not understand Here should some brainstorming take place … We could try to assemble a list of open issues we want to discuss with Craig… For instance: • Isn’t there any averaging (since we use large amounts of photons)? • GEO-spectrum of Holo noise: The Signal-Recycling cavity does not really change the storage times of the light… ILIAS WG1, March 2008

14. Contents of this presentation • Attempt to explain: “What is holographic noise?” • Craig’s predictions • Points we (experimentalists) do not understand • Comparison of Craig’s prediction with noise measured in GEO600 • How to go on from here … ILIAS WG1, March 2008

15. GEO’s Mystery noise • For a long time we observe a unexplained noise component in GEO600. • Shows up as a gap between the sum of all known noises (yellow) and the actual senstivity (black). • Details available at: • Mystery-noise-Wiki http://www.sr.bham.ac.uk/dokuwiki/doku.php?id=geonoise:home • http://www.ego-gw.it/ILIAS-GW/WP1docs/hild_231007.ppt • http://www.ego-gw.it/ILIAS-GW/WP1docs/hild1_050308.ppt ILIAS WG1, March 2008

16. Noise projection including Holographic Noise • Using Holographic noise prediction from arXiv:0806.0665v2 1.6e-22/sqrt(Hz) for f>550 Hz and 1/f below for f<550 Hz. • If Holographic noise prediction is correct, it could explain most of the mystery noise. ... but ... ILIAS WG1, March 2008

17. ... but ... Please keep in mind: • Eventhough we worked very hard to ensure the correctness of the projections, they might not represent the full truth: • Projections only account for linear noise coupling • Some projections might underestimate the actual noise contribution (frequency noise) • Some noise sources might still be undiscovered • Holographic noise is only one of several potential candidates that might be able to mystery noise… ILIAS WG1, March 2008

18. Projection including increasedBS thermo refractive noise • Using a BS thermo refactive noise 3.4 times higher than we believe it to be seems to explain the mystery noise as well. ILIAS WG1, March 2008

19. Contents of this presentation • Attempt to explain: “What is holographic noise?” • Craig’s predictions • Points we (experimentalists) do not understand • Comparison of Craig’s prediction with noise measured in GEO600 • How to go on from here … ILIAS WG1, March 2008

20. How can we go on from here? • The two main contributor to the GEO sensitivity are mystery noise and shot noise • We can change the tuning of the Signal-Recycling mirror change the shape of the shot noise. Shot noise in GEO600 for different SR detunings ILIAS WG1, March 2008

21. Statistical analysis • Need to do noise projections at several SR detunings. • Derive shape of mystery noise for the different detunings. • Use Baysian statistics to put a hard number on how well Craigs predictions explain the mystery noise and compare this to numbers how well a 1/f noise or a flat noise can reproduce the mystery noise. Example of earlier mystery noise mea- surements or different SR detunings ILIAS WG1, March 2008

22. EXTRA SLIDES ILIAS WG1, March 2008

23. Holographic spacetime • “Relative spacetime positions of events are indeterminate.” • “Spacetime positions defined to the precision of information propagation and measurement allowed by the capacity of Planck wavelength radiation.” • (Planck radiation: UV cutoff at Planck kength) ILIAS WG1, March 2008

24. L-shape versus triangle arXiv:0706.1999v2 ILIAS WG1, March 2008