Stefan Hild for the GEO600 team

16th ILIAS WG1 meeting, July 2008, Birmingham

Holographic Noise in GEO600?

Stefan Hild ILIAS WG1, March 2008 Slide 2

Articles on Holographic Noise available on arXiv:

arXiv:0806.0665v2

arXiv:0710.4153v2

arXiv:0709.0611v1

arXiv:0706.1999v2

arXiv:astro-ph/0703775v4

Stefan Hild ILIAS WG1, March 2008 Slide 3

Published article on Holographic Noise

Stefan Hild ILIAS WG1, March 2008 Slide 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 …

Stefan Hild ILIAS WG1, March 2008 Slide 5

Spacetime

Space time is not continuous, but quantized.

Assumption:smallest length is the Planck wavelength

This gives a fundamental limit for measurements

Stefan Hild ILIAS WG1, March 2008 Slide 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.

Stefan Hild ILIAS WG1, March 2008 Slide 7

Indeterminancy of transverse Positions

Angles are indeterminate at Planck scale:

Relative Transverse Positions are uncertain. Uncertainty increases at larger separation:

Stefan Hild ILIAS WG1, March 2008 Slide 8

Holographic shear noise

PRD 77, 104031

Stefan Hild ILIAS WG1, March 2008 Slide 9

Characteristic of a random walk

The spectrum of a random walk is 1/f in ASD.

Time series of a random walk PSD of random walk time series

Stefan Hild ILIAS WG1, March 2008 Slide 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 …

Stefan Hild ILIAS WG1, March 2008 Slide 11

Craigs Predictions from arXiv:0806.0665v2

Zero-parameter estimates

GEO600:

LIGO:

f < 550Hz

f > 550Hz

f > 150Hz

f < 150Hz

Stefan Hild ILIAS WG1, March 2008 Slide 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 …

Stefan Hild ILIAS WG1, March 2008 Slide 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…

Stefan Hild ILIAS WG1, March 2008 Slide 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 …

Stefan Hild ILIAS WG1, March 2008 Slide 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

Stefan Hild ILIAS WG1, March 2008 Slide 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.

Stefan Hild ILIAS WG1, March 2008 Slide 17

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…

Stefan Hild ILIAS WG1, March 2008 Slide 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.

Stefan Hild ILIAS WG1, March 2008 Slide 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 …

Stefan Hild ILIAS WG1, March 2008 Slide 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

Stefan Hild ILIAS WG1, March 2008 Slide 21

Statistical analysisNeed 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 earliermystery noise mea-surements or differentSR detunings

Stefan Hild ILIAS WG1, March 2008 Slide 22

EXTRA

SLIDES

Stefan Hild ILIAS WG1, March 2008 Slide 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)

Stefan Hild ILIAS WG1, March 2008 Slide 24

L-shape versus triangle

arXiv:0706.1999v2