S. Chelkowski Slide 1WG1 Meeting, Birmingham 07/2008

Overview Quantum noise in gravitational wave detectors

Generation of squeezed states

Using squeezing in a gravitational wave detector

Frequency dependent squeezing

Generation of squeezing in the gravitational wave frequency band

Best squeezing measurements so far

Squeezed light in GEO600

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 2

A simple gravitational wave detector

3S. Chelkowski WG1 Meeting, Birmingham 07/2008

S. Chelkowski WG1 Meeting, Birmingham 07/2008 4

Quantum noise limited sensitivity

Shot Noise Radiation Pressure Noise

factor 100 in power= factor 10 in sensitivity= factor 1000 in event rate

S. Chelkowski WG1 Meeting, Birmingham 07/2008 5

Squeezed light enhanced interferometer

S. Chelkowski WG1 Meeting, Birmingham 07/2008 6

Squeezed light enhanced interferometer

20dB of squeezing= factor 10 in sensitivity= factor 1000 in event rate

S. Chelkowski WG1 Meeting, Birmingham 07/2008 7

Amplitude-Quadrature

Phase-Quadrature

Heisenberg uncertainty relation

An explanation of squeezing

coherent state

squeezed state

S. Chelkowski WG1 Meeting, Birmingham 07/2008 8

Vacuum Noise

S. Chelkowski WG1 Meeting, Birmingham 07/2008 9

Squeezed Vacuum

S. Chelkowski WG1 Meeting, Birmingham 07/2008 10

• Strong interaction between seed- and pump field

• MgO:LiNbO3 – crystal as nonlinear material

• Phase matching via temperature

• Fractions in phase get amplified, out of phase deamplified

OPA - optical parametric amplification

1064nm532nm

S. Chelkowski WG1 Meeting, Birmingham 07/2008 11

• MgO:LiNbO3 2 x 2.5 x 6.5mm• 7% doping• bikonvex or plane/konvex rc=8mm• coatings @ 1064 and 532nm

Side A: AR (R < 0.05%)Side B: HR (R > 99.98%)

• hemilithic Resonator @ 1064nm coupling mirror R = 96.7%Finesse = 180

FSR = 3.9GHz• phasematching temp. ~65°C• temp. stabilized via peltier elements

New oven design

S. Chelkowski WG1 Meeting, Birmingham 07/2008 12

Dark Noise

Broadband squeezing up to 30MHz

Relaxation oscillation of the Laser

Vacuum noise

Squeezing results from a normal OPA

Squeezing in a real gravitational wave detector

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 13

S. Chelkowski WG1 Meeting, Birmingham 07/2008 14

GEO600

S. Chelkowski WG1 Meeting, Birmingham 07/2008 15

Quantum noise in GEO600

S. Chelkowski WG1 Meeting, Birmingham 07/2008 16

Reducing the quantum noise

S. Chelkowski WG1 Meeting, Birmingham 07/2008 17

amplitude squeezing

Reducing the quantum noise

S. Chelkowski WG1 Meeting, Birmingham 07/2008 18

Reducing the quantum noise

S. Chelkowski WG1 Meeting, Birmingham 07/2008 19

Effect of a detuned filter cavity

Squeezed Vacuum Interaction with a cavity

S. Chelkowski WG1 Meeting, Birmingham 07/2008 20

amplitude squeezing

+45°-45°

Reducing the quantum noise

S. Chelkowski WG1 Meeting, Birmingham 07/2008 21

Reducing the quantum noise

Frequency-dependent squeezed light

How can we create it?

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 22

S. Chelkowski WG1 Meeting, Birmingham 07/2008 23

Chelkowski et al.,PRA 71, 013806 (2005)

Frequency-dependent squeezing

Detuned locked to +15MHz

S. Chelkowski WG1 Meeting, Birmingham 07/2008 24

Chelkowski et al.,PRA 71, 013806 (2005)

Squeezing

Vacuum Noise

Anti-Squeezing

Phase quadrature

Amplitude quadrature

Frequency-dependent squeezing

A rotating squeezing ellipse – FC detuning +15MHz

S. Chelkowski WG1 Meeting, Birmingham 07/2008 25

Chelkowski et al.,PRA 71, 013806 (2005)

A rotating squeezing ellipse – FC detuning +15MHz

S. Chelkowski WG1 Meeting, Birmingham 07/2008 26

Chelkowski et al.,PRA 71, 013806 (2005)

S. Chelkowski WG1 Meeting, Birmingham 07/2008 27

Chelkowski et al.,PRA 71, 013806 (2005)

+15 MHz -15 MHz

Angle of the squeezing ellipse

Generation of squeezed light on the gravitational wave frequency

band

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 28

S. Chelkowski WG1 Meeting, Birmingham 07/2008 29

Generic squeezing from an OPA

Dark Noise

broadband Squeezing up to 30MHz

Relaxation oscillation of the Lasers

Vacuum noise

S. Chelkowski WG1 Meeting, Birmingham 07/2008 30

• Seed field carries technical noise from the laser.

• Technical noise is imprinted onto the squeezed field.

• Seed field is needed for the generation of error signals.

OPA – optical parametric amplification

S. Chelkowski WG1 Meeting, Birmingham 07/2008 31

Seed field is a control field

S. Chelkowski WG1 Meeting, Birmingham 07/2008 32

OPA without seed turns into an OPO

S. Chelkowski WG1 Meeting, Birmingham 07/2008 33

Setup for low frequency squeezing

homodyne angle

squeezing angle

S. Chelkowski WG1 Meeting, Birmingham 07/2008 34

Setup for low frequency squeezing

homodyne angle

squeezing angle

S. Chelkowski WG1 Meeting, Birmingham 07/2008 35

Setup for low frequency squeezing

homodyne angle

squeezing angle

S. Chelkowski WG1 Meeting, Birmingham 07/2008 36

Setup for low frequency squeezing

homodyne angle

squeezing angle

Measured vacuum noise

37

vacuum noise for 176µWvacuum noise for 88µWvacuum noise for 44µW

3dB3dB

S. Chelkowski WG1 Meeting, Birmingham 07/2008

Measured squeezed vacuum noise

38

vacuum noise for 88µW

squeezed vacuum noise

Chelkowski et al., PRA 75, 043814 (2007)

~6dB

S. Chelkowski WG1 Meeting, Birmingham 07/2008

Squeezed vacuum enhanced Michelson interferometer

S. Chelkowski WG1 Meeting, Birmingham 07/2008 39

Best squeezing measurements so far

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 40

Optical layout

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 41

Vahlbruch et al. PRL 100, 033602 (2008)

Measured squeezing

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 42

Vahlbruch et al. PRL 100, 033602 (2008)

Squeezed light in GEO600

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 43

S. Chelkowski WG1 Meeting, Birmingham 07/2008 44

GEO HF: Detuned Signal Recycling

S. Chelkowski WG1 Meeting, Birmingham 07/2008 45

GEO HF: Tuned Signal Recycling

S. Chelkowski WG1 Meeting, Birmingham 07/2008 46

Do we need a filter cavity?

Conclusion

Squeezed light can be used to reduces the quantum noise in gravitational wave detectors

Reflection at a detuned cavity creates frequency dependent light

Without a filter cavity, tuned signal recycling is the best choice

All needed techniques for the implementation of squeezed light into a gravitational wave detector are developed

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 47

Appendix

S. Chelkowski WG1 Meeting, Birmingham 07/2008 Slide 48

49

GEO 600 Layout

GEO 600:

50

3dB SQZ:

6dB SQZ:

GEO HF Layout: short 8m Filter Cavity

51

3dB SQZ:

6dB SQZ:

GEO HF Layout: long 1200m Filter Cavity