Jason Hogan May 22, 2014 LISA Symposium X Single-arm
gravitational wave detectors based on atom interferometry
Slide 2
Are multiple baselines required? L (1 + h sin(t )) strain
frequency Single Baseline Gravitational Wave Detection Motivation
Formation flying: 2 vs. 3 spacecraft Reduce complexity, potentially
cost Laser interferometer GW detector
Slide 3
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
Mirror Atom fringes
Slide 4
Measurement Concept Essential Features 1.Atoms are good clocks
2.Light propagates across the baseline at a constant speed Atom
Clock Atom Clock L (1 + h sin(t ))
Slide 5
Simple Example: Two Atomic Clocks Time Phase evolved by atom
after time T
Slide 6
Simple Example: Two Atomic Clocks Time GW changes light travel
time Phase difference
Slide 7
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.
Slide 8
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).
Slide 9
Two-photon vs. single photon configurations 2 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).
Slide 10
Laser frequency noise insensitive detector Graham, et al.,
arXiv:1206.0818, PRL (2013) Laser noise is common Excited state
Pulses from alternating sides allow for sensitivity enhancement
(LMT atom optics)
Slide 11
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.
Excited state
Slide 12
Reduced Noise Sensitivity Differential phase shifts (kinematic
noise) suppressed by v/c < 310 -11 1. Platform acceleration
noise a 2. Pulse timing jitter T 3. Finite duration of laser pulses
4. Laser frequency jitter k Leading order kinematic noise
sources:
Slide 13
Satellite GW Antenna Common interferometer laser L ~ 100 - 1000
km Atoms JMAPS bus/ESPA deployed
Slide 14
Potential Strain Sensitivity J. Hogan, et al., GRG 43, 7
(2011).
Slide 15
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)
Slide 16
Ground-based GW technology development 4 cm Long duration Large
wavepacket separation
Slide 17
10 m Drop Tower Apparatus
Slide 18
Interference at long interrogation time 2T = 2.3 sec Near full
contrast 6.710 -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 ( 87 Rb)
Slide 19
Preliminary LMT in 10 m apparatus 7 cm wavepacket separation 10
k 4 cm wavepacket separation 6 k LMT using sequential Raman
transitions with long interrogation time. LMT demonstration at 2T =
2.3 s (unpublished)
Slide 20
Atom Lens position time Geometric Optics: Atom Lens:
Slide 21
Atom Lens Cooling Optical Collimation: Atom Cooling: position
time
Slide 22
Radial Lens Beam point source AC Stark Lens Apply transient
optical potential (Lens beam) to collimate atom cloud in 2D
Time
Slide 23
2D Atom Refocusing Without Lens With Lens Lens
Slide 24
Record Low Temperature North West Vary Focal Length
Slide 25
Extended free-fall on Earth Lens Launch Lens Relaunch Detect
Launched to 9.375 meters Relaunched to 6 meters Image of cloud
after 5 seconds total free-fall time Towards T > 10 s
interferometry (?)
Slide 26
Future GW work Single photon AI gradiometer proof of concept
Ground based detector prototype work MIGA; ~1 km baseline (Bouyer,
France) 10 m tower studies
Slide 27
27 AOSense 408-735-9500 AOSense.com Sunnyvale, CA 6 liter
physics package As built view with front panel removed in order to
view interior. Sr compact optical clock
Slide 28
Collaborators NASA GSFC Babak Saif Bernard D. Seery Lee
Feinberg Ritva Keski-Kuha Stanford Mark Kasevich (PI) Susannah
Dickerson Alex Sugarbaker Tim Kovachy Christine Donnelly Chris
Overstreet Theory: Peter Graham Savas Dimopoulos Surjeet Rajendran
Former members: David Johnson Sheng-wey Chiow Visitors: Philippe
Bouyer (CNRS) Jan Rudolph (Hannover) AOSense Brent Young (CEO)