Post on 28-Jan-2021
Jason HoganJuly 24, 2018
Undergraduate Summer Research
Seminar
Precision atom interferometry for
fundamental physics
Atom interference
Light interferometer
Atom interferometer
Atom
http://scienceblogs.com/principles/2013/10/22/quantum-erasure/
http://www.cobolt.se/interferometry.html
Light fringes
Beam
splitte
r
Beam
splitte
r
Mirro
r
Atom fringes
Light
Atom optics using light
ħkv = ħk/m
ħk
(1) Light absorption:
(2) Stimulated emission:
Atom optics using light
ħkv = ħk/m
ħk
(1) Light absorption:
(2) Stimulated emission:
Rabi oscillations
Time
In practice, typically 2-photon Raman or Bragg transitions
Atom
Beam
splitte
r
Beam
splitte
r
Mirro
r
Light Pulse Atom Interferometry
p/2 pulse “beamsplitter”
p pulse “mirror”
“beamsplitter”p/2 pulse
•Interior view |p+k>
|p >
Time
Posi
tion
Light Pulse Atom Interferometry
• Long duration
• Large wavepacket separation
10 meter scale atomic fountain
Interference at long interrogation time
Wavepacket separation at apex (this data 50 nK)
Dickerson, et al., PRL 111, 083001 (2013).
Interference (3 nK cloud)
Port 1
Port 2
2T = 2.3 seconds
1.4 cm wavepacket separation
54 cm
Large space-time area atom interferometry
Long duration (2 seconds), large separation (>0.5 meter) matter wave interferometer
Kovachy et al., Nature 2015
90 photons worth of momentum
max wavepacketseparation
World record wavepacket separation due to multiple laser pulses of momentum
Large space-time area atom interferometry
2 ħk
90 ħk
Robust interference observed at macroscopic time and length scales
Kovachy et al., Nature 2015
Phase shift from spacetime curvature
Spacetime curvature across a single particle's wavefunction
General relativity: gravity = curvature (tidal forces)
Curvature-induced phase shifts have been described as first true manifestation of gravitation in a quantum system
Gravity Gradiometer
Gradiometer interference fringes
10 ћk 30 ћk
Gradiometer baseline defined by atom recoil:
(Insensitive to initial source position)
P. Asenbaum et al., PRL 2017.
Phase shift from tidal force
Gradiometer response to 84 kg lead test mass
Asenbaum et al., PRL 118, 183602 (2017)
Upper interferometer
Lower interferometer
Equivalence Principle
Bodies fall at the same rate, independent of composition
Why test the EP?
▪ Foundation of General Relativity
▪ Quantum theory of gravity (?)
▪ Search for new forces, dark matter
C. Will, Living Reviews
mg = ma
EP Bounds from Classical Experiments
𝜂 𝑀, 𝐸 = −1.0 ± 1.4 × 10−13
Williams et al, PRL 2004
©news.cnrs.fr
Lunar laser ranging:
Torsion pendula: 𝜂 𝐵𝑒, 𝑇𝑖 = 0.3 ± 1.8 × 10−13
Schlamminger et al, PRL 2008
©npl.Washington.edu
MICROSCOPE satellite: 𝜂 𝑇𝑖, 𝑃𝑡 = −0.1 ± 1.3 × 10−14
Touboul et al, PRL 2017
©CNES, D. Ducros
Phase shear readout
Measure phase + contrast in one shot
(Sugarbaker et al, PRL 2013)
Suppresses time varying effects (mirror motion, laser phase, etc.)
Bragg Interferometer
• Common Bragg laser beams
• Common velocity selection
• AC stark shift compensation
Simultaneous dual species interferometers
10ħk Dual Species Run
Rb-85
Rb-87
Rb-85 and Rb-87
are in phase
2T = 1.8 s
Megaparsecs…
Gravitational waves science:
• New carrier for astronomy: Generated by moving mass instead of electric charge
• Tests of gravity: Extreme systems (e.g., black hole binaries) test general relativity
• Cosmology: Can see to the earliest times in the universe
L (1 + h sin(ωt ))
strain
frequency
Gravitational Wave Detection
Laser Interferometer Detectors
Gound-based detectors: LIGO, VIRGO, GEO (> 10 Hz)
Space-based detector concept: LISA
(1 mHz – 100 mHz)
Gravitational wave frequency bands
Mid-band
There is a gap between the LIGO and LISA detectors (0.1 Hz – 10 Hz).
Moore et al., CQG 32, 015014 (2014)
Mid-band Science
Mid-band discovery potential
Historically every new band/modality has led to discovery
Observe LIGO sources when they are younger
Optimal for sky localization
Predict when and where events will occur (before they reach LIGO band)
Observe run-up to coalescence using electromagnetic telescopes
Astrophysics and Cosmology
Black hole, neutron star, and white dwarf binaries
Ultralight scalar dark matter discovery potential
Early universe stochastic sources? (cosmic GW background)
Sky position determination
λ
Sky localization precision:
Mid-band advantages
- Small wavelength λ
- Long source lifetime (~months) maximizes effective R
Images: R. Hurt/Caltech-JPL; 2007 Thomson Higher Education
R
Measurement Concept
Essential Features
1. Light propagates across the baseline at a constant speed
2. Atoms are good clocks
Atom
Clock
Atom
Clock
L (1 + h sin(ωt ))
Simple Example: Two Atomic Clocks
Time
Phase evolved by atom after time T
Atom clock
Atom clock
Simple Example: Two Atomic Clocks
GW changes light travel time
Time
Atom clock
Atom clock
Gradiometer sensor design
• Compare two (or more) atom ensembles separated by a large baseline
• Science signal is differential phasebetween interferometers
• Differential measurement suppresses many sources of common noise and systematic errorsM
easu
rem
ent
Base
line g
Science signal strength is proportional to baseline length (DM, GWs).
Clock Gradiometer
atoms
atoms
Projected gravitational wave sensitivity
Dots indicate remaining lifetimes of 10 years, 1 year, 0.1 years, and 0.01 years
MAGIS-100 detector at Fermilab
• MINOS, MINERνA, NOνA experiments use NuMI beam
• 100 meter access shaft – 100 meter atom interferometer
• Search for dark matter coupling in the Hz range
• Intermediate step to full-scale detector for GWs
Source 1
Source 2
50 m
ete
rs50 m
ete
rs
100 m
ete
rs
Source 3
Matter wave Atomic Gradiometer Interferometric Sensor
Stanford MAGIS prototype
Atom optics laser
(M Squared SolsTiS)
Trapped Sr atom cloud
(Blue MOT)
Sr gradiometer CAD
(atom source detail)
Two assembled Sr atom sources
Collaborators
Rb Atom InterferometryMark Kasevich
Tim Kovachy
Chris Overstreet
Peter Asenbaum
Remy Notermans
Theory:Peter Graham
Savas Dimopoulos
Surjeet Rajendran
Asimina Arvanitaki
Ken Van Tilburg
MAGIS-100:
Joseph Lykken (Fermilab)
Robert Plunkett (Fermilab)
Swapan Chattopadhyay (Fermilab/NIU)
Jeremiah Mitchell (Fermilab)
Roni Harnik (Fermilab)
Phil Adamson (Fermilab)
Steve Geer (Fermilab)
Jonathon Coleman (Liverpool)
Sr Atom InterferometryTJ Wilkason
Hunter Swan
Jan Rudolph
Yijun Jiang
Ben Garber
Benjamin Spar
Connor Holland