1. Center for Gravitational-wave Astrophysics David Reitze University of Florida

2. Vision A 3 rd generation gravitational-wave detector is absolutely essential for answering fundamental questions in physics and astronomy The Center for Gravitational-wave Astrophysics (CGA) will lead the R&D for a U.S. 3 rd generation gravitational-wave detector The CGA will deliver multi-disciplinary frontier science: – Precision measurement beyond the Standard Quantum Limit – Gravitational-wave physics and astrophysics – Novel optical materials and devices The PFC funding model is perfectly suited for the CGA 8/27/20152

3. Enabling frontier physics on many fronts 8/27/20153 Quantum Mechanics of Macroscopic Objects NOW: Mode selective cooling of a 10 kg LIGO mirror to 1.4 uK (234 quanta!) FUTURE: Cooling of 40 kg mirrors to quantum ground state Quantum Optics for Gravitational-wave detection NOW: Use of squeezed light for sub-shot noise limited sensing FUTURE: Novel interferometric sensing methods to go beyond the Standard Quantum Limit Precision Astrophysics NOW: Measuring the roundness of a neutron star to 1 part in 10 7 or 1 mm (PSR J0613−0200) FUTURE: Precisely measure the space-time geometry during binary black hole mergers State-of-the-Art Lasers and Optics NOW: Nd:YAG laser frequency stabilization to < 10 -22 ; large mirror surface figures with < 1 nm deviation FUTURE: development of cryogenic silicon optics; ultra- stabilized lasers at 1.55  m B. P. Abbott et al. 2010 Ap.J. 713 671Abbott et al 2009 New J. Phys. 11 073032Abadie et al 2011 submitted quantitatively determine nuclear matter equation of state

4. Gravitational Waves 8/27/20154 Gravitational waves or ‘ripples’ in space-time are miniscule dynamic strains (DL/L < 10 -21 ) which require extreme precision interferometry (DL) and very long arm lengths (L) Very strong yet indirect evidence: measurements of orbital decay of binary pulsar PSR1913+16 by Hulse and Taylor, and several additional similar systems Gravitational waves are unique probes of the most violent astrophysical events in the universe: black hole mergers, supernovae, Big Bang

5. GW-Detection schemes/detectors 8/27/20155 f [log 10 Hz] 4 1-9-15-18-6 Inflation Probe Pulsar Timing LISALIGO NANOGrav Collaboration Sources: Background from MBH-binaries Reach critical sensitivity: 2015 -5 LIGO, VIRGO, LCGT, GEO Sources: NS/BH mergers Supernovae Pulsars... Reach critical sensitivity: 2015 Sources: SMBH mergers EMRIs Galactic binaries Guaranteed signals Largest SNR Being re-scoped Polarization in  -Wave Background Source: Density Fluctuations Gravitational Waves 2020+

6. Third generation gravitational-wave astrophysics DUNCAN TO PROVIDE 8/27/20156

7. Why the time is right to fund the CGA now! The path from concepts and proof-of-principle experiments to an operational interferometer is 20 years long – Initial LIGO: first design study completed in 1983, construction proposal 1989, construction completed 1999, design sensitivity science run Nov 2005-Sept 2007 – Advanced LIGO: design study completed in 1998, construction proposal 2006, planned first data 2015, design sensitivity ~2016, discovery ~2017 Discovery will drive demand - worldwide call by astronomers and astrophysicists for higher SNR, more detections, better localization, broader frequency coverage, … as soon as the first gravitational wave is discovered! The path to a 3 rd generation gravitational wave detector might look like… – design study 2015 at the earliest, construction proposal 2020+, first light ~2030, design sensitivity ~2032 But only if we get started now! – European funded roadmap for 3 rd generation Einstein Telescope was just delivered, see http://blogs.nature.com/news/2011/05/post_78.htmlhttp://blogs.nature.com/news/2011/05/post_78.html 8/27/20157

8. But wait!! Shouldn’t we wait for results from Advanced LIGO?? We ’ ll surely learn important instrument science lessons from Advanced LIGO (not just discover gravitational waves!) – Advanced LIGO can make important new discoveries about the nature of gravitational waves and their sources. – Must address high power handling, thermal noise… We are certain that a 3 rd generation interferometer will need to use drastically different technologies in several areas. – Those technologies will need to be developed, no matter what. Some of the research programs we are proposing can be used in Advanced LIGO to improve sensitivity or as alternatives should there be a problem with Advanced LIGO – e.g., optical filter cavities, seismic arrays, low frequency suspensions. Note that there will plenty of time to incorporate any relevant technical lessons from aLIGO into the 3G interferometer design. 8/27/20158

9. 2015-2025: 2 nd Generation Gravitational Wave Detectors GEO HF Germany Advanced VIRGO Italy Advanced LIGO Louisiana, USA Advanced LIGO Washington, USA LCGT Japan Advanced LIGO Australia?

10. 8/27/2015 2011: Coordinated 3 rd Generation Research Programs

11. 8/27/2015 2030+: 3rd Generation Gravitational Wave Detectors Einstein Telescope Europe

12. Quantum-enhanced Precision Interferometry Heisenberg Uncertainty Principle – Imposes Interferometry Standard Quantum Limit (SQL) – Not a strict limit for strain sensing Goals: – Demonstrate technology that can surpass the SQL for O(100kg) test masses Techniques: – Mitigate thermal noise (Silicon & cryogenic) – Exploit quantum correlations Squeezed light sources Interferometer topology (filter cavity, speed-meter) 8/27/201512 Nature 464, 697-703, 2010 Nano-Mechanical oscillator in ground state (Nature 2009) Quantum mechanics with atoms (Schrödinger 1926) Quantum limited Interferometry for m=150kg (GCA)

13. CGA Major Activities and How They Fit Together DUNCAN TO PROVIDE 8/27/201513

14. CGA Education and Outreach Pipeline of activities spanning middle school to graduate school – including all CGA sites and partners – including postdocs as mentors and active participants APS Physics Quest  High School interns and teacher training,  College interns and women speakers series  graduate summer school in experimental physics 8/27/201514

15. CGA: a geographically dispersed PFC 7 Universities, 22 faculty investigators. Dispersion == strength. No single institution could focus 22 faculty lines in a single area. LIGO and LSC participation has taught most CGA faculty how to collaborate beyond campus walls. Communication is essential and built in. – biweekly telecons of each Major Activity (EVO, video, …) – monthly telecons of the entire CGA – twice yearly face-to-face meetings of CGA particpants – ad-hoc face-to-face meetings at the LSC meetings: “open to all” meetings to advertise the CGA to the LIGO community The Quiet Optical Test Facility -- a gathering place for experimenters. Affiliates, visiting fellows, national and international partners play an important role. A number of workshops each year. 8/27/201515

16. Change in PFC director Dave Reitze to become the Executive Director of the LIGO Laboratory – At Caltech this summer; will be on leave from UF and will remain affiliated with PFC researchers David Tanner to assume the role of CGA Director – Distinguished Professor at UF – former Physics Department Chair, – Chair of the APS Division of Condensed Matter Physics 2006-2007 – Associate director UF Microfabritech The CGA organizational structure will remain the same – UF will retain lead institution status; Campanelli will retain Associate Directorship The personnel and structure of the CGA are such that this change will not have a major impact – We have a ‘deep bench’ --- both technical and management. 8/27/201516

17. Why a Third Generation GW research needs a PFC now A PFC-type Center for Gravitational Astrophysics is essential to advance the field beyond Advanced LIGO Timely & forward-looking – must start now to achieve a working 3 rd generation detector in 2030 Aggressive – measurement precision beyond the standard quantum limit! – large-scale underground detector! Potential to lead to a major advance – the science case for a 3 rd generation gravitational-wave observatory is compelling – much technology to be developed. A mix of disciplines and talents – designing a 3 rd generation gravitational-wave observatory requires coordination among a broad spectrum of scientific disciplines 8/27/201517

18. Back up slides 8/27/201518

19. Why this group? Some of us have been involved with LIGO Faculty investigators working with but not consumed by aLIGO The Quiet Optical Test Facility 8/27/201519

20. Management Exec Board: Budgets; internal reviews; recommends adding or phasing out projects; selects director from among participants. Director: Liaison with NSF/Universities; report submission; facilities; organizes meetings; identifies problems to EB. 3 year terms for all, staggered in case of EB. 8/27/201520

21. Example 3G strain sensitivity 8/27/201521 Xylophone LF + HF detector 10x lower freq. 10x lower strain Sub-SQL sensitivity

22. Squeezed light source Quantum trade-off between phase and amplitude noise Strain sensing is only sensitive to one of them Can be generated in Optical Parametric Oscillator Technology at 1.6u not ready 8/27/201522 Wigner functions of squeezed states (Nature 387, 471 – 475, 1997) Schematic representation of Electric field, various states

23. Squeezed light source Conceptual layout of squeezer Light is frequency- doubled in SHG Squeezed vacuum created in OPO Control loops for cavity and phase locking 8/27/201523

24. Interferometer configurations Several layouts for sub-SQL interferometry have been proposed – None have been experimentally demonstrated – Technical challenges, sensitivity to real world losses, technical noise couplings, etc. 8/27/201524 Two very different speed-meter configurations

25. DUSEL Status Recent DUSEL developments have limited implications for the CGA activities. Homestake mine will continue to support scientific research over the coming 2-3 years (and likely longer) through a combination of private and federal funding. This period will be sufficient to complete the measurements we planned for the Homestake mine. Further, our interest is not limited to the Homestake location: –We will conduct a systematic survey of (surface and underground) locations across the US that could potentially host such a 3G detector. While Homestake appears promising, it remains to be seen whether the seismic noise levels and geological structure at Homestake are indeed optimal for a 3G gravitational-wave detector. 8/27/201525

26. Seismic and Newtonian Noise Seismic and Newtonian (gravity- gradient) noise sources dominate below 10 Hz in surface detectors. Newtonian noise sources: –Seismic waves (dominated by surface waves). –Atmospheric fluctuations. –Human factor (traffic etc). Newtonian (strain-equivalent) noise estimate: ~10 -20 Hz -1/2 at 1 Hz. –Need to suppress it by 10 3 –10 4 x. 8/27/201526

27. Mitigating Newtonian Noise Survey US locations in terms of seismic noise and atmospheric conditions. Underground option: –Controllable environment, atmospheric and human-induced effects suppressed. –Surface seismic waves exponentially suppressed with depth (10x at 1 Hz). Active suppression of seismic contribution: –Monitor the rock motion, feedback to interferometer mirrors. –Need a large array of underground seismic stations. –Testing the feasibility of this option at the Homestake mine. 8/27/201527 Average seismic levels at 1.1 Hz USArray seismometer data

28. Homestake Project 8/27/201528 Current 8-element array of seismic stations at Homestake. Propose to expand the array to ~30 stations, with a full 3D configuration. Seismic spectrum at 4100 ft depth. Homestake is remarkably quiet!

29. Underground vs Space Cost of boring multi-kilometer tunnels is certainly substantial. –Of order $100M-$300M, depending on length, geology etc. –For comparison, initial LIGO cost was $280M. Already being demonstrated by the LCGT project in Japan: L-shape interferometer, 3km arms. European design study for Einstein Telescope already completed, assumes underground environment: triangular shape, 10km sides. 3G detectors would be complementary to satellite-based interferometer, which will probe frequencies around 1 mHz. Cancellation of LISA leave the future of the US contribution to the satellite-based detectors rather uncertain. It is critical for the US to initiate a systematic and detailed design study for 3G gravitational wave detectors to maintain the leadership momentum and the competitive edge generated by LIGO. 8/27/201529

30. LCGT 8/27/201530 Large-scale Cryogenic Gravitational-wave Telescope Kamioka, Japan 3km arms, L-shaped Observations starting ~2017.

31. Einstein Telescope 8/27/201531 Artist’s impression of Einstein Telescope Marco Kraan, Nikhef, ET science team Triangular, 10 km arms, Cryogenic, 6x detectors. PFC research could contribute in an effective way Paper design so far Much enabling technology “to be” done

32. 8/27/201532 Low-Frequency Suspensions FmFm N N S S FgFg FmFm FgFg Pendulum suspension provides f -2 suppression of motion above resonant frequency. To operate at ~1 Hz, need resonant frequency ~0.1 Hz  25m long pendulum! Possible alternative: cancel the gravitational restoring force with magnetic or electrostatic forces, lowering the resonant frequency. Propose to investigate low-frequency pendulum designs.

33. 33 George Hobbs, CSIRO The Gravitational Wave Spectrum CMBpol Planck Ground-based Interferometers Advanced LIGO: 2015 Advanced Virgo: 2015 Einstein Telescope: 2025 ? Space-based Interferometers NGO: 2022 ? (formerly LISA) Ground-based Radio Astronomy NanoGrav: 2015 SKA: 2020 ?