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 cost Laser interferometer GW detector

Atom interference Light interferometer Atom interferometer Atom Light fringes Beamsplitter Mirror Atom fringes

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(ωt ))

Simple Example: Two Atomic Clocks Time Phase 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, , (2008). Yu, et al., GRG 43, 1943, (2011).

Two-photon vs. single photon configurations 2 photon transitions 1 photon transitions Rb Sr How to incorporate LMT enhancement? Graham, et al., PRD 78, , (2008). Yu, et al., GRG 43, 1943, (2011).

Laser frequency noise insensitive detector Graham, et al., arXiv: , PRL (2013) Laser noise is common Excited state Pulses from alternating sides allow for sensitivity enhancement (LMT atom optics)

LMT enhancement with single photon transition Graham, et al., arXiv: , PRL (2013) Example LMT beamsplitter (N = 3) Each pair of pulses measures the light travel time across the baseline. Excited state

Reduced Noise Sensitivity Differential phase shifts (kinematic noise) suppressed by  v/c < 3× 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:

Satellite GW Antenna Common interferometer laser L ~ km 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 sec Near full contrast 6.7× g/shot (inferred) Interference (3 nK cloud) Wavepacket separation at apex (this data 50 nK) Dickerson, et al., PRL 111, (2013). Demonstrated statistical resolution: ~5 × g in 1 hr ( 87 Rb)

Preliminary LMT in 10 m apparatus 7 cm wavepacket separation 10 ħk 4 cm wavepacket separation 6 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 Lens Apply 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 meters Relaunched to 6 meters Image of cloud after 5 seconds total free-fall time Towards T > 10 s interferometry (?)

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

27 AOSense AOSense.com Sunnyvale, CA 6 liter physics package As built view with front panel removed in order to view interior. Sr compact optical clock

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)