jason hogan may 22, 2014
DESCRIPTION
Single-arm gravitational wave detectors based on atom interferometry. LISA Symposium X. Jason Hogan May 22, 2014. Single Baseline Gravitational Wave Detection. frequency. L (1 + h sin( ω t )). strain. Are multiple baselines required?. Motivation Formation flying: 2 vs. 3 spacecraft - PowerPoint PPT PresentationTRANSCRIPT
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Jason Hogan
May 22, 2014
LISA Symposium X
Single-arm gravitational wave detectors based on atom interferometry
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Are multiple baselines required?
L (1 + h sin(ωt ))
strain
frequency
Single Baseline Gravitational Wave Detection
Motivation• Formation flying: 2 vs. 3 spacecraft• Reduce complexity, potentially costLaser
interferometer GW detector
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Atom interference
Light interferometer
Atom interferometer
Atom
http://scienceblogs.com/principles/2013/10/22/quantum-erasure/http://www.cobolt.se/interferometry.html
Light fringes
Beamsplitter
Beamsplitter
Mirror
Atom fringes
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Measurement Concept
Essential Features
1. Atoms are good clocks2. Light propagates across the baseline at a constant speed
AtomClock
AtomClock
L (1 + h sin(ωt ))
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Simple Example: Two Atomic Clocks
TimePhase evolved by atom after time T
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Simple Example: Two Atomic Clocks
Time GW changes light travel time
Phase difference
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Phase Noise from the Laser
The phase of the laser is imprinted onto the atom.
Laser phase noise, mechanical platform noise, etc.
Laser phase is common to both atoms – rejected in a differential measurement.
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Single Photon Accelerometer
Three pulse accelerometer
Long-lived single photon transition (e.g. clock transition in Sr, Yb, Ca, Hg, etc.)
Graham, et al., PRD 78, 042003, (2008).Yu, et al., GRG 43, 1943, (2011).
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Two-photon vs. single photon configurations2 photon transitions 1 photon transitions
Rb Sr
How to incorporate LMT enhancement?
Graham, et al., PRD 78, 042003, (2008).Yu, et al., GRG 43, 1943, (2011).
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Laser frequency noise insensitive detector
Graham, et al., arXiv:1206.0818, PRL (2013)
Laser noise is common
Excitedstate
Pulses from alternating sides allow for sensitivity enhancement (LMT atom optics)
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LMT enhancement with single photon transition
Graham, et al., arXiv:1206.0818, PRL (2013)
Example LMT beamsplitter (N = 3)
Each pair of pulses measures the light travel time across the baseline.
Excitedstate
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Reduced Noise Sensitivity
Differential phase shifts (kinematic noise) suppressed by Dv/c < 3×10-11
1. Platform acceleration noise da2. Pulse timing jitter dT3. Finite duration Dt of laser pulses4. Laser frequency jitter dk
Leading order kinematic noise sources:
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Satellite GW Antenna
Common interferometer laser
L ~ 100 - 1000 km
Atoms Atoms
JMAPS bus/ESPA deployed
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Potential Strain Sensitivity
J. Hogan, et al., GRG 43, 7 (2011).
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Technology development for GW detectors
1) Laser frequency noise mitigation strategies
2) Large wavepacket separation (meter scale)
3) Ultra-cold atom temperatures (picokelvin)
4) Very long time interferometry (> 10 seconds)
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Ground-based GW technology development
4 cm• Long duration• Large wavepacket separation
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10 m Drop Tower Apparatus
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Interference at long interrogation time
2T = 2.3 secNear full contrast6.7×10-12 g/shot (inferred)
Interference (3 nK cloud)
Wavepacket separation at apex (this data 50 nK)
Dickerson, et al., PRL 111, 083001 (2013).
Demonstrated statistical resolution: ~5 ×10-13 g in 1 hr (87Rb)
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Preliminary LMT in 10 m apparatus
7 cm wavepacket separation10 ħk
4 cm wavepacket separation6 ħk
LMT using sequential Raman transitions with long interrogation time.
LMT demonstration at 2T = 2.3 s (unpublished)
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Atom Lens
position
time
Geometric Optics:
Atom Lens:
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Atom Lens Cooling
Optical Collimation:
Atom Cooling:
position
time
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Radial Lens Beam“point source”
AC Stark LensApply transient optical potential (“Lens beam”) to collimate atom cloud in 2D
Time
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2D Atom Refocusing
Without Lens
With Lens
Lens
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Record Low Temperature
North
West
Vary Focal Length
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Extended free-fall on Earth
Lens
Launch Lens Relaunch Detect
Launched to 9.375 metersRelaunched to 6 meters
Image of cloud after 5 seconds total free-fall
time
Towards T > 10 s interferometry (?)
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Future GW workSingle photon AI gradiometer proof of concept
Ground based detector prototype work
MIGA; ~1 km baseline (Bouyer, France)
10 m tower studies
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27AOSense 408-735-9500AOSense.comSunnyvale, CA
6 liter physics package
As built view with front panel removed in order to view interior.
Sr compact optical clock
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CollaboratorsNASA GSFC
Babak SaifBernard D. Seery Lee FeinbergRitva Keski-Kuha
Stanford Mark Kasevich (PI)Susannah DickersonAlex SugarbakerTim KovachyChristine DonnellyChris Overstreet
Theory:Peter GrahamSavas DimopoulosSurjeet Rajendran
Former members:David Johnson Sheng-wey Chiow
Visitors:Philippe Bouyer (CNRS)Jan Rudolph (Hannover)
AOSenseBrent Young (CEO)