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GEO600: The First Application of Squeezed Light PowerPoint Presentation

GEO600: The First Application of Squeezed Light

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### GEO600: The First Application of Squeezed Light

Roman Schnabel, for the GEO600 group, the Quantum Interferometry Group, and the LSC

Albert-Einstein-Institut (AEI)

Institut für Gravitationsphysik

Leibniz Universität Hannover

Outline

- Introduction to Squeezed Light
- The first squeezed-light laser for GW detectors
- Sensitivity improvement of GEO600 with squeezed light
- Squeezed light as a key-technology for GW astronomy

Gravitational Waves

h:

Gravitational wave astronomy requires observatories that can detect

h < 10-23

(over a band from e.g. 100Hz - 200Hz)

- Merging neutron stars. Numerical relativity simulation of gravitational waves emitted from two neutron stars which are about to merge in 4 ms [Rezzolla, AEI].

3

Mirror 2

Laser

50% Beam splitter

Photo diode

Gravitational Wave Detection1) Test masses

> km

2) Laser light

3) Interference

Photo-electric current

modulated at GW frequency

4) Photo-electric effect

4

Photo-Electric Current

(No signal, but photon shot noise)

Photons per time interval

Time intervals

5

Photon Counting Statistics

Coherent state

Relative shot-noise

Probability [rel. units]

Photon number N

7

Photo diode

Increasing the Light PowerMirror 1

Power-recycling mirror

High power laser

Mirror 2

Photo-electric current

8

- Is there a possibility to increase the signal/quantum noise–ratio without increasing the laser power?

Yes, by squeezed laser light!

9

Shot-Noise in an Interferometer noise–ratio without increasing the laser power?

Mirror

Beam splitter

Laser

Due to zero point fluctuations

(vacuum noise)

Photo

diode

[Caves, Phys. Rev. D 23, 1693 (1981)]

10

Squeezing the Shot-Noise noise–ratio without increasing the laser power?

Mirror

C. M. Caves (1981):

Reduction of quantum noise with squeezed light

Beam splitter

Laser

Squeezed

light laser

Faraday

Rotator

Photo

diode

[Caves, Phys. Rev. D 23, 1693 (1981)]

11

“Squeezed” Counting Statistics noise–ratio without increasing the laser power?

Squeezing factor: 10 dB

Noise squeezing

Probability [rel. units]

Squeezing factor: 3 dB

Photon number N

12

N noise–ratio without increasing the laser power?

Photo-Electric Current(No signal)

Photons per time interval

Time intervals

13

N noise–ratio without increasing the laser power?

Photo-Electric Current - SqueezedSqueezing the noise of a random process without a measurement!?

Quantum mechanics:

Squeezing requires time/energy (and amplitude/phase quadrature) entangled photons

Photons per time interval

Time intervals

14

Squeezing in the Wave Picture noise–ratio without increasing the laser power?

X1

Quadrature squeezing at sideband frequency W1

+

+

Wc-W1

+

Wc+W1

Wc

X2

W

+

15

The GEO600 Squeezed Light Laser noise–ratio without increasing the laser power?

16

Generation of Squeezed Light (PDC) noise–ratio without increasing the laser power?

c2-nonlinear crystal:

MgO:LiNbO3

Pump field input

(cw, 532nm)

Squeezed field output

(cw, 1064nm) by parametric down-conversion (PDC)

Standing wave cavity

17

History of Squeezed Light Generation noise–ratio without increasing the laser power?

First squeezed light: [Slusher et al., PRL 55, 2409 (1985)]

Research labs with squeezed light (not complete):

- Kimble (CalTech): teleportation: [Furuzawa et al., SCIENCE 282, 706 (1998)]
- Grangier (Orsay); kitten: [Ourjoumtsev et al., SCIENCE, 312, 83 (2006)]
- Schiller and Mlynek (Konstanz): tomography: [Nature 387, 471 (1997).]
- Bachor and Lam (Canberra): 6dB at 1064nm [J. Opt. B 1, 469 (1999).]
- Leuchs (Erlangen); ~7 dB pulsed [Opt. Lett. 33, 116 (2008).]
- Polzik (Copenhagen), [Neergaard-Nielsen et al., PRL 97, 083604 (2006)]
- Furusawa (Tokyo); 9 dB: [Takeno et al., Opt. Express 15, 4321 (2007).]
- Fabre (Paris), Zhang, Peng (Shanxi);
- Andersen (Copenhagen); Mavalvala (MIT),...

18

History of Squeezed Light Generation noise–ratio without increasing the laser power? Recent review: [R.S. et al., Nature Comm. 1:121 doi: 10.1038/ncomms1122 (2010)]

Research & development towards the first application of squeezed light

- McClelland (ANU), power-recycling [McKenzie et al., PRL 88, 231102 (2002)]
- McClelland (ANU), audio-band [McKenzie et al., PRL 93, 161105 (2004)]
- RS (LUH), signal-recycling [Vahlbruch et al., PRL 95, 211102 (2005)]
- RS (LUH), control scheme [Vahlbruch et al., PRL 97, 011101 (2006)]
- RS (LUH), full band-width [Vahlbruch et al., New Journal of Phys. 9, 371 (2007)]
- Mavalvala (MIT), suspended mirrors [Goda et al., Nature Phys. 4, 472 (2008)]
- RS (LUH), 10dB [Vahlbruch et al., PRL 100, 033602 (2008)]
- RS (LUH), turn-key source [Vahlbruch et al., CQG 27, 084027 (2010)]

19

Transport to the GEO600 GW Detector noise–ratio without increasing the laser power?

20

GEO600: Squeezed Light in Application noise–ratio without increasing the laser power?

Observatory noise

without squeezed light

With squeezed light

Squeezing the Shot-Noise (SN) noise–ratio without increasing the laser power?and the Radiation Pressure Noise (PRN)

[Jaekel and Reynaud,

Europhys. Lett. 13, 301 (1990)]

Laser

Filter cavities

Faraday

Rotator

Squeezed

light laser

[Kimble et al., Phys. Rev. D 65, 022002 (2001)]

22

QND-Regime noise–ratio without increasing the laser power?

Squeezing SN and RPN[Jaekel, Reynaud 1990]

Shot noise

Squeezed Light Input

(8dB)

Radiation pressure noise

(SQL)

Summary noise–ratio without increasing the laser power?

- GEO600 now uses squeezed light and achieves its best ever sensitivity (at shot-noise limited frequencies)
- A real application of entangled photons in squeezed light has been realized
- Squeezing is mature and might become a key-technology in all future GW observatories, such as ET

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