Roman Schnabel for the AEI-Division Karsten Danzmann Measurement and Observation at the Quantum Limit at the Albert-Einstein Institute Hannover Roman Schnabel for the AEI-Division Karsten Danzmann

AEI-Division Prof. Karsten Danzmann Dr. Hartmut Grote Gravitational wave detector GEO600 Dr. Harald Lück GEO600+HF and Einstein Telescope Priv.-Doz. Dr. Benno Willke Laser Development, and Advanced LIGO Dr. Stefan Goßler 10 m Prototype facility* Priv.-Doz. Dr. Gerhard Heinzel Space Interfero-metry Prof. Roman Schnabel Quantum Interfero-metry * Led by external member Prof. Ken Strain, Glasgow

The GEO600 Project Michelson Laser Interferometer (600m) for GW detection German-British collaboration, location Hannover / Germany Limited by quantum noise U Birmingham U Mallorca Glasgow

GEO 600 GEO-HF: - 30kW - DC readout - OMC - Tuned, broadband SR H. Grote GEO 600 GEO-HF: - 30kW - DC readout - OMC - Tuned, broadband SR - Squeezed Light C. Caves (1981): Replace the vacuum state (zero-point fluctuations) by a squeezed state! 4 4

Shot noise squeezed

This is not just a proof of principle! GEO600 regularly uses squeezed light during its observational runs. An application of quantum metrology today! Regular use: [Grote, Danzmann, Dooley, Schnabel, Vahlbruch, Phys. Rev. Lett., accepted (2013)]

The Einstein-Telescope H. Lück The Einstein-Telescope 10 km arms under ground Cryo-cooled silicon mirrors 500 W @ 1064 nm Squeezed light at 1064 nm and 1550 nm (~10 dB) [M. Punturo et al., Class. Quantum Grav. 084007 (2010)] European conceptual design study, delivered May 2011 7

The Advanced LIGO 180 W-Laser B. Willke The Advanced LIGO 180 W-Laser LIGO Livingston Design and fabrication at the AEI/LZH. Three pre-stabilized 180 W- systems installed at LIGO. [Winkelmann et al., Appl. Phys. B. (2011); Kwee et al., Opt. Express (2012)] 8

Light Power Stabilisation B. Willke Light Power Stabilisation Relative power noise (shot-noise limited): 2 10-9 Hz- 1/2 4 Photodiodes, 50mA each, aligned for lowest pointing coupling 9

Light Power Stabilisation (>MHz) B. Willke Light Power Stabilisation (>MHz) Relative power noise of 150W: RPN=10-10 Hz-1/2 corresponding to 32 A photo current. 10

134 W of TEM00 green light B. Willke 1064nm (in) 130W @ 1064nm (out) 134W @532nm (130W in TEM00), single frequency, single mode, 90% conversion efficiency, stable for more than 48 hours. [T. Meier et al., Opt. Lett. 35, 3742 (2010)] 11

82 W of light in the LG33 Mode B. Willke Transfer of 140W HG00 into 82W LG33 with 95% mode purity. Offers reduction of thermal noise in future GW detectors. On-going collaboration with University of Birmingham. 12

The 10m-AEI-Prototype Facility S. Goßler / K. Strain The 10m-AEI-Prototype Facility UHV system, 180° view 100 m3 volume, currently @ about 5 x10-8 mbar (dominated by water vapour, air in 10-9 mbar region) 13

The 10m-AEI-Prototype Facility S. Goßler / K. Strain The 10m-AEI-Prototype Facility Suspended Tables, fres < 300 mHz 14

Vertical Isolation Performance S. Goßler / K. Strain Vertical Isolation Performance 101 100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-1 100 101 102 Vertical ground motion Noise spectral density [ mm / Hz -1/2 ] Vertical table motion Theoretical model Frequency [Hz] 15

Monolithic Mirror Suspensions S. Goßler / K. Strain Monolithic Mirror Suspensions First blade spring stage Design: IGR Glasgow Monolithic Stages: Mechanics: AEI Hannover Upper mass with second blade spring stage Penultimate mass 20µm suspension fibers 100g mirror 16

Squeezed Light R. Schnabel Wigner function of >10dB squeezed vacuum state Parametric down-conversion in c2-nonlinear crystal in standing-wave cavity [Vahlbruch et al., Phys. Rev. Lett. (2008)] [Vahlbruch et al., New J. Phys. (2007)] [Eberle et al., Phys. Rev. Lett. (2010)] [Mehmet et al., Opt. Express (2011)] [Ast et al., Opt. Lett. (2012)] 17

Squeezed Light R. Schnabel Observed squeezing: Up to 12.7 dB @ 1064 nm Spectrum down to 1 Hz / up to 1 GHz The GEO600 Squeezer: Fully controlled, automated source of up to 10 dB from 10 Hz to > 10 kHz Parametric down-conversion in c2-nonlinear crystal in standing-wave cavity [Vahlbruch et al., Phys. Rev. Lett. (2008)] [Vahlbruch et al., New J. Phys. (2007)] [Eberle et al., Phys. Rev. Lett. (2010)] [Mehmet et al., Opt. Express (2011)] [Ast et al., Opt. Lett. (2012)] 18

The GEO600 Squeezed Light Laser R. Schnabel The GEO600 Squeezed Light Laser 19

Entangled Light for Metrology R. Schnabel Entangled Light for Metrology Einstein- Podolsky- Rosen entangled light beams [S. Steinlechner et al., arXiv:1211.3570] 20

Nano-Structured Mirrors R. Schnabel Nano-Structured Mirrors On-going collaboration with Jena University and IGR Glasgow Goal: reduction of mirror thermal noise Up to 100% Reflection (surface waveguide mirror) 0th -1st +1st 0th Finesse ~ 3000 Si crystal Destruktive Interference [Brückner, RS, Tünnermann et al., Phys. Rev. Lett. 104, 163903 (2010)] 21

Nano-Structured Mirrors R. Schnabel Nano-Structured Mirrors On-going collaboration with Jena University and IGR Glasgow Goal: reduction of mirror thermal noise Joint publications on nano-structured mirrors, suspended in the Glasgow 10m prototype facility Barr, Strain, Tünnermann, RS et al., Opt. Lett. 36, 2746 (2011). Friedrich, Strain, Tünnermann, RS et al., Opt. Express 19, 14955 (2011). Edgar, Strain, Tünnermann, RS et al., Class. Quantum Grav. 27, 084029 (2010). Edgar, Strain, Tünnermann, RS et al., Opt. Lett. 34, 3184 (2009). Hallam, Strain, RS et al., J. Opt. A: Pure Appl. Opt. 11, 085502 (2009). 22

Absorption Measurements on Silicon R. Schnabel Absorption Measurements on Silicon T = 300 K [J. Steinlechner et al., submitted to Class. Quantum Grav. (2013)] 23

Opto-Mechanics R. Schnabel 40 nm thickness meff = 80 ng Q-factor = 500.000 fres = 130 kHz R = 17 % @ 1064 nm J. D. Thompson, … & J. G. E. Harris, Nature 452, 72-75 (2008) T.J. Kippenberg and K.J. Vahala, Science 321, 1172 (2008) 24

Optically cooled membrane resonance: R. Schnabel Opto-Mechanics Optically cooled membrane resonance: From 300K to 8K 25

Proposal for an AEI / IGR IMPP Topic: “Ultra-quite Mirror Test Masses” Goals: Design and test of novel low-noise kg-sized mirror systems Possibly based on silicon For GW detectors operated at low temperatures For quantum physical experiments with massive objects Further strengthening the GWD related expertise in north Europe GEO600: 5 kg fused silica mirror with monolithic fibre suspension 26

Proposal for an AEI / IGR IMPP Topic: “Quantum Non-Demolition Interferometry” Goals: Design and test of novel interferometer techniques to surpass the standard quantum limit of gravitational wave detection generating entangled motion of kg-sized test masses (conditional states) A. Franzen, AEI Michelson interferometer with two readouts proposed for the generation of entangled mirrors 27

A B X1com(t) X2diff(t) BHD: Low finesse Michelson Interferometer with 2x balanced homodyne detection (BHD): ® Information on which the mechanical state can be conditioned* *also: [M. Haixing, S. Danilishin, H. Müller-Ebhardt, Y. Chen, New J. Phys. 12, 083032 (2010)] 28

Conditionally Pure Mirror States pA(t) − pB(t) xA(t) − xB(t) Problem: Thermal occupation number of mechanical oscillator: For pendulum with period 1s: W = 2p Hz n<1 ! ® T < 4∙10-10 K ! 29

Summary The AEI’s expertise: Operation and improvement of GEO600 Design activity on the Einstein Telescope Ultra-stable high-power laser light Squeezed and entangled light A new low-noise 10m prototype facility Research on nano-structured and silicon mirrors Opto-mechanics with micro-oscillators Combining these with the expertise in Scotland (IGR Glasgow) on GW detectors, low noise mirror suspensions, and low temperature experiments will provide an outstanding position for R&D for GW detectors and quantum physical experiments with massive objects.