Jason Hogan May 22, 2014
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Transcript of Jason Hogan May 22, 2014
Jason Hogan
May 22, 2014
LISA Symposium X
Single-arm gravitational wave detectors based on atom interferometry
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
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
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 ))
Simple Example: Two Atomic Clocks
TimePhase evolved by atom after time T
Simple Example: Two Atomic Clocks
Time GW changes light travel time
Phase difference
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.
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).
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).
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)
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
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:
Satellite GW Antenna
Common interferometer laser
L ~ 100 - 1000 km
Atoms Atoms
JMAPS bus/ESPA deployed
Potential Strain Sensitivity
J. Hogan, et al., GRG 43, 7 (2011).
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)
Ground-based GW technology development
4 cm• Long duration• Large wavepacket separation
10 m Drop Tower Apparatus
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)
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)
Atom Lens
position
time
Geometric Optics:
Atom Lens:
Atom Lens Cooling
Optical Collimation:
Atom Cooling:
position
time
Radial Lens Beam“point source”
AC Stark LensApply transient optical potential (“Lens beam”) to collimate atom cloud in 2D
Time
2D Atom Refocusing
Without Lens
With Lens
Lens
Record Low Temperature
North
West
Vary Focal Length
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 (?)
Future GW workSingle photon AI gradiometer proof of concept
Ground based detector prototype work
MIGA; ~1 km baseline (Bouyer, France)
10 m tower studies
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
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)