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Several Fun Research Projects at NAOJ for the Future GW Detectors

Picture: Sora Kawamura. Several Fun Research Projects at NAOJ for the Future GW Detectors. LIGO Seminar @ Caltech Aug. 8, 2006 Seiji Kawamura National Astronomical Observatory of Japan. National Astronomical Observatory of Japan (NAOJ). NAOJ is located in Tokyo.

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Several Fun Research Projects at NAOJ for the Future GW Detectors

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  1. Picture: Sora Kawamura Several Fun Research Projectsat NAOJfor the Future GW Detectors LIGO Seminar @ Caltech Aug. 8, 2006 Seiji Kawamura National Astronomical Observatory of Japan

  2. National Astronomical Observatory of Japan (NAOJ) NAOJ is located in Tokyo. TAMA300 is located on the NAOJ campus.

  3. Other research projectsat NAOJ • Displacement-noise free Interferometer • RSE • DECIGO • MHz GW detection • QND

  4. Displacement-noise free Interferometer

  5. Motivation • Displacement noise: seismic Noise, thermal noise, radiation pressure noise • Cancel displacement noise  shot noise limited sensitivity • Increase laser power  sensitivity improved indefinitely Diplacement noise Displacement noise Cancel displacement noise Shot noise Sensitivity Increase laser power PD Laser Frequency

  6. Principle 1: GW and mirror motion interact with light differently Difference outstanding for GW wavelength  distance between masses GW On reflection On propagation Light Mirror motion Mirror motion

  7. Principle 2: Mirror motion can be cancelled by combining interferometer outputs • Increase # of mirrors • Implement many interferometers • Take combination outputs  cancel mirror motion Laser Mirror motion PD Laser Mirror motion PD Bi-directional MZ

  8. Example of DFI • Two 3-d bi-directional MZ • Take combination of 4 outputs • Mirror motion completely cancelled • GW signal remains (f 2)

  9. Experiment (Ideal) • One bi-directional MZ GW Laser Mirror motion PD Extract GW  Mirror motion

  10. ～ ～ Experiment (Practical) • EOM used for GW and mirror motion Simulated mirror motion Simulated GW Mirror motion GW Laser Laser PD PD IdealPractical

  11. Results • Mirror motion cancels out • GW signal remains GW signal to output Difference Mirror motion to output Difference Mirror motionGW signal

  12. Next step • Implement cavity to reduce the effective frequency • Demonstrate the cancellation of the BS motion using two bi-directional MZ References • Kawamura and Chen, PRL, 93, (2004) 211103 • Chen and Kawamura, PRL, 96 (2006) 231102 • Chen, Pai, Somiya, Kawamura, Sato, Kokeyama, Ward, submitted to PRL (gr-qc/0603054) • Sato, Kawamura, Kokeyama, Ward, Chen, Pai, and Somiya, to be submitted to PRL

  13. RSE

  14. 4m RSE • Supended mass RSE • Miniature suspension system

  15. Previous Accomplishments • Tuned RSE (w/o PRM) locked • Detuned RSE (w/o PRM) locked • Optical spring effect observed • Miyakawa, Somiya, Heinzel, and Kawamura, Class. and Quantum Grav., 19 (2002) p.1555-1560 • Somiya, Beyersdorf, Arai, Sato, Kawamura, Miyakawa, Kawazoe, Sakata, Sekido, Mio, Appl. Opt. 44 (2005) pp. 3179-3191

  16. Current Activity • Try new signal extraction method • Backup for Advanced LIGO • Baseline for LCGT • Lock RSE (w/ PRM)

  17. New Signal Extraction Method

  18. ls diagonal lp Signal Matrix Black: Analytic results Red: Numerical simulation using “FINESSE” ls orthogonal Baseline Design for LCGT lp

  19. Delocation • Option for LCGT - Could have potential advantages

  20. Current Status • MZ locked only w/ PM • FP Michelson locked • Suspension system improved

  21. DECIGO

  22. 10-18 10-20 10-22 10-24 What is DECIGO? Deci-hertz Interferometer Gravitational Wave Observatory - bridges the gap between LISA and terrestrial detectors. - could attain high sensitivity because of lower confusion noise. LISA Terrestrial Detectors Strain [Hz-1/2] DECIGO Confusion Noise 10-4 102 100 104 10-2 Frequency [Hz]

  23. Pre-conceptual Design FP-Michelson interferometer Arm length: 1000 km Laser power: 10 W Laser wavelength: 532 nm Mirror diameter: 1 m Mirror mass: 100 kg Finesse: 10 Orbit and constellation: TBD Drag-free satellite Arm cavity PD Laser Arm cavity Kawamura, et al., CQG 23 (2006) S125-S131 PD Drag-free satellite Drag-free satellite

  24. Drag-free and FP Cavity Displacement Signal between S/C and Mirror Local Sensor Mirror Thruster Thruster Actuator Displacement signal between the two Mirrors

  25. Requirements [Practical force noise] • 4x10-17 N/Hz per mirror [Frequency Noise] @ 1 Hz • First-stage stabilization： 1 Hz/Hz • Stabilization gain by common-mode arm length： 105 • Common-mode rejection ratio： 105

  26. BH+BH(1000Msun) @z=1 NS+NS@z=1 Correlation for 3 years Science by DECIGO • NS-NS (1.4+1.4Msun) • z<1 (SN>26: 7200/yr) • z<3 (SN>12: 32000/yr) • z<5 (SN>9: 47000/yr) • IMBH (1000+1000Msun) • z<1 (SN>6000)

  27. Acceleration of Expansion of the Universe Expansion＋Acceleration? DECIGO GW NS-NS (z～1) Output Template (No Acceleration) Strain Real Signal ? Phase Delay～1sec (10 years) Time Seto, Kawamura, Nakamura, PRL 87, 221103 (2001)

  28. Roadmap for DECIGO 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 R&D Advanced R&D PF1 Observation Design & Fabrication PF2 Design & Fabrication Observation DECIGO 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

  29. DECIGO Pathfinder1 Objectives • Drag-free system • Cavity locking in space • Modest sensitivity at 0.1 – 1 Hz Local Sensor Thruster Actuator

  30. DECIGO Pathfinder2 Objectives • DECIGO with modest specification • Cavity locking between two satellites • Meaningful sensitivity Drag-free satellite Arm cavity PD Laser Arm cavity PD Drag-free satellite Drag-free satellite

  31. Release Hold Release Hold Release Hold DECIGO Simulator Objectives • Continual free-fall environment • Clamp release • Modest sensitivity down to 0.1Hz • Possibility of long arm Clamp 2m Vertical Position 1 sec Time

  32. DECIGO Demonstrator Thruster Thruster Satellite A Satellite B Mirror B Mirror A Actuator Local sensor Local sensor Air-hockey table Objectives • Lock acquisition

  33. Budget and Working Group • Will submit a budget request ($18M for 6 years) this fall • R&D for DECIGO • PF1 • w/ Pulsar Timing • DECIGO-WG: 120 members currently

  34. MHz GW detection

  35. Objectives and Scope • Detect GW at MHz • Develop technologies for synchronous recycling GW Sources at MHz • Inspiral of mini black holes • GW from inflation period

  36. Synchronous Recycling Recycling Mirror Laser BS Drever, 1983 Dark Fringe Photo detector

  37. Response of Synchronous Recycling x h t y y x GW l GW  4 l Laser BS GW effect synchronously enhanced! Photo detector

  38. Plan for Table-top Experiment Integration for 1 year h  10-26 Hz-1/2 F  105 h  10-21 Hz-1/2 l  75 cm fGW  100 MHz

  39. Current Status • Locked w/ low Finesse • Noise Spectrum taken F  100 f 1 Non 50:50 Beam splitter 1 DOF to control EOM f 1 f GW - f 1 - BW Output

  40. First Noise Spectrum

  41. QND

  42. Objectives and Scope • Beat SQL using ponderomotive squeezing • Use FP Michelson w/ super light mirrors Plan • Observe radiation pressure noise • Reduce radiation pressure noise w/ homodyne detection • Beat SQL • Expand the effective frequency range

  43. Ponderomotive Squeezing • Squeezed by phase change caused by reflection by free mass Squeezing: frequency dependent Cannot beat SQL w/ RF method Laser Noise Signal Caves, Walls & Milburn, Braginsky & Khalili, ... Vacuum

  44. Signal Noise Laser Local light Homodyne phase Homodyne Detection S/N can be improved by choosing appropriate homodyne phase!

  45. Quantum Noise • Radiation pressure noise can be completely cancelled at one frequency • The frequency depends on homodyne phase

  46. Strategy • Use super-light mirror • Use high finesse • Increase radiation pressure noise • Easier to detect • Use tuned IFO (no optical spring)

  47. Design Parameter and Noise Estimate

  48. Current Status • Homodyne detection method verified • Vacuum tank ready • Design of set-up complete • Fiber of 10 m drawn successfully

  49. The End

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