Post on 09-Feb-2016
description
Atom Interferometer Gyroscope
James GreenbergUniversity of Arizona Physics
Motivation: Precision Inertial Measurements
Test General RelativityNavigation
Reproduced from Jentsch et al. Gen. Relativ. Gravit. (2004)
From http://marsrover.nasa.gov/
From http://www.jhartfound.org/
http://www.nasa.gov/mission_pages/gpb/
Atom Interference Fringes
1G 2G 3G
Atom Beam
p = grating period =
Measurements: Phase and Contrast
ΔΦ
V
𝐶=max−minmax+min
Atom Beam
1G 2G 3G
1G 2G 3G
𝑣<𝑣0𝑣=𝑣0𝑣>𝑣0
Dispersion Contrast Loss𝑣0
large
𝜃∝ 1𝑣Velocity Distribution
𝜃
Dispersion Compensation
Φ𝐶𝑚𝑎𝑥≠0
Measured Contrast vs. Change in Phase
= Rotation RateL = grating separationp = grating period
Φ𝑆𝑎𝑔𝑛𝑎𝑐=4𝜋 𝐿2Ω𝑣𝑝
Reproduced from Lenef et al. PRL (1997)
Sagnac Phase (Shift)
Φ𝐶𝑚𝑎𝑥<0
From http://www.physicalgeography.net/
= 73rad/s 2.4rad shift
= Rotation RateL = grating separationp = grating period
Φ𝑆𝑎𝑔𝑛𝑎𝑐=4𝜋 𝐿2Ω𝑣𝑝
= 73rad/s 2.4rad shift
Reproduced from Lenef et al. PRL (1997)
Sagnac Phase (Shift)
From http://www.physicalgeography.net/
Acceleration Phase (Shift)Φ𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛=
2𝜋 𝐿2𝑔sin 𝜃𝑏𝑡 𝑣2𝑝
�⃗�𝜃𝑏𝑡
∆ 𝑥
1G
2G
3Gx
z
y
1 board tilt 4 radian phase shift
= Board tilt angleL = grating separationp = grating period
L
Model and Results
-20 mrad -1.15
10% uncertainty
Earth Rotation Rate
If board tilt assumed to be -20 mrad, then:
73 rad/s
13% Uncertainty
Summary of Work
• Determined inertial phase shifts from C() for multiple beam conditions
• Modeled C() data to fit measured • Measured board tilt and Earth rotation rate
codependently with 10% and 13% precision respectively
Thank You!
• Special thanks to:– Dr. Alex Cronin – Maxwell Gregoire– Raisa Trubko– Tyler St. Germaine– UA NASA Space Grant Staff
• Funding from:– NSF– NASA Space Grant