New directions for terrestrial detectors

Transcription

1 New directions for terrestrial detectors The next ten years Nergis Mavalvala (just a middle child) Rai s party, October 2007

2 Rai-isms Zacharias s picture This isn t half stupid = brilliant! What do you know how to do? Well, I ve taken 8.07, 8.08,, Oh come off it, what do you really know? Err, I can machine. You re alright Squash or swimming?

3 Rai-isms I gotta pee, walk with me to the boy s room. (At door) Err Unh, you can t come with me. I ll be right out (1991) Rai, I can t read your annotation here (Long pause, staring at page) I can t read it either (1996) Q: What s a reasonable start-up to ask for, Rai? A: I think it ll be hard to go for more than $50,000 (2001)

4 Why do we need new directions? Because Rai is never really going to retire

5 The ideas out there Will they work, or are we crazy? Sub-quantum-limited interferometers Novel classical readouts Quantum mechanical antics Subterranean interferometers Cryogenic detectors

6 Quantum noise limited Shot noise h( f ) 1 P Weiss LIGO Radiation pressure noise P h( f ) M f 2 4 Advanced LIGO

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8 Sub-quantum interferometers

9 Quantum mechanics of light Heisenberg Uncertainty Principle for EM field ˆ + ˆ ΔX ΔX 1 Coherent state (laser light) Squeezed state Two complementary observables Make on noise better for one quantity, BUT it gets worse for the other X + and X associated with amplitude and phase McKenzie

10 Quantum Noise in an Interferometer Laser X X + X X + First proposed C.M. Caves, PR D (1981) Proof-of-principle demonstration M. Xiao et al., PRL (1987) More realistic configurations demonstrated Power Recycled Michelson K. McKenzie et al., PRL (2002) Power and Signal Recycled Michelson H. Vahlbruch et al., PRL (2005) Suspended prototype Goda et al. (2007)

11 Squeezed input

12 Squeezed Input Interferometer Laser GW Detector Squeeze Squeeze Source Source Faraday isolator Homodyne Detector GW Signal

13 Sub-quantum-limited interferometer Standard config. Broadband config. with squeezing Broadband config. without squeezing h(f) (1/ Hz 1/2 ) Narrowband unsqueezed Broadband unsqueezed Broadband Squeezed f (Hz) X Quantum correlations Input squeezing X +

14 Squeezing the 40m Caltech Goda et al. (2007)

15 40m squeezing gang

16 High laser power radiation pressure mechanical oscillator coupling

17 Radiation-mirror coupling 1. Light with amplitude fluctuations ΔA incident on mirror Movable mirror 3. Phase of reflected light Δφ depends on mirror position and hence light amplitude, i.e ΔΑ Δx Δφ Remember LLAMA? 2. Radiation pressure due to ΔA causes mirror to move by Δx

18 Key ingredients Low mass, low noise mechanical oscillator mirror 1 gm with 1 Hz resonant frequency High circulating power 10 kw High finesse cavities Differential measurement common-mode rejection to cancel classical noise Optical spring noise suppression and frequency independent squeezing A radiation pressure dominated interferometer laser source 1 W end mirror (1 gm) 10 kw input mirror (250 gm) BS squeezed light (vacuum)

19 Observable quantum effects Squeezed states of light Entanglement due to mirror motion Quantum radiation pressure noise Squeezed states of the mirror Figure of merit for quantumness Thermal occupation number N = Like atoms kt Optical cooling and trapping of the mini-mirror B hω eff eff

20 Classical radiation pressure effects Stiffer than diamond 6.9 mk Stable OS Radiation pressure dynamics Optical cooling

21 Quantum radiation pressure effects Entanglement Squeezing Mirror-light entanglement Squeezed vacuum generation

22 Radiation pressure gang Nick Smith Tim Bodiya Dave Ottaway Rai s door art

23 Novel readouts Evading the back action noise radiation pressure

24 Novel readouts Speedmeters Measure momentum, not position Optical bar and optical lever configurations Use radiation pressure to transfer the motion of end masses to vertex for local readout Intra-cavity readouts Potential to operate at high sensitivity with much lower power than conventional interferometers

25 Subterranean detectors

26 Get off the ground! Density perturbations fluctuating gravitational forces You can t walk but roller skates are fine

27 Cryogenic detectors

28 Beating down thermal noise F th 4 ktφ ω, T B mat M ( ) Intrinsic material loss LCGT Optical coatings I. Martin et al (2006)

29 In closing Very much in the future Cryogenics Subterranean or space observatories Coming soon(er) to an observatory near you Quantum radiation pressure manipulation Squeezing The best kind of squeezed state

30 The best kind of squeezed states

31 Annual Lab Hike Tomorrow White Mountains All are invited