Precision for fundamental physics

Undergraduate Summer Research Seminar

Jason Hogan July 24, 2018 Atom interference

Light interferometer

Light Light fringes Beamsplitter

Atom Atom fringes

interferometer Beamsplitter

Atom Mirror

http://scienceblogs.com/principles/2013/10/22/quantum-erasure/ http://www.cobolt.se/interferometry.html Atom optics using light

(1) Light absorption:

ħk v = ħk/m

(2) Stimulated emission:

ħk Atom optics using light

(1) Light absorption:

Rabi oscillations ħk v = ħk/m

(2) Stimulated emission:

ħk Time

In practice, typically 2-photon Raman or Bragg transitions

Light Pulse Atom Interferometry Beamsplitter

p/2 pulse “beamsplitter”

Position Beamsplitter

“mirror” Atom p pulse Mirror

Time “beamsplitter” p/2 pulse

|p > •Interior view |p+k> Light Pulse Atom Interferometry

• Long duration

• Large wavepacket separation 10 meter scale atomic fountain Interference at long interrogation time

Port 1

Port 2

Wavepacket separation at apex (this data 50 nK) 2T = 2.3 seconds 1.4 cm wavepacket separation

Interference (3 nK cloud)

Dickerson, et al., PRL 111, 083001 (2013). Large space-time area atom interferometry max wavepacket separation Long duration (2 seconds), large separation (>0.5 meter) matter interferometer

90 photons worth of momentum

World record wavepacket separation due to multiple pulses of momentum

54 cm

Kovachy et al., Nature 2015 Large space-time area atom interferometry

Robust interference observed at macroscopic time and length scales

2 ħk 90 ħk

Kovachy et al., Nature 2015 Phase shift from spacetime curvature

Spacetime curvature across a single particle's wavefunction

General relativity: = curvature (tidal forces)

Curvature-induced phase shifts have been described as first true manifestation of gravitation in a quantum system Gravity Gradiometer

Gradiometer baseline defined by atom recoil:

(Insensitive to initial source position)

Gradiometer interference fringes

10 ћk 30 ћk

P. Asenbaum et al., PRL 2017. Phase shift from tidal force

Gradiometer response to 84 kg lead test mass

Upper interferometer

Lower interferometer

Asenbaum et al., PRL 118, 183602 (2017) Equivalence Principle

mg = ma

Bodies fall at the same rate, independent of composition

C. Will, Living Reviews

Why test the EP? ▪ Foundation of ▪ Quantum theory of gravity (?) ▪ Search for new forces, dark matter EP Bounds from Classical Experiments

Lunar laser ranging: 휂 푀, 퐸 = −1.0 ± 1.4 × 10−13 Williams et al, PRL 2004

©news.cnrs.fr

Torsion pendula: 휂 퐵푒, 푇푖 = 0.3 ± 1.8 × 10−13 Schlamminger et al, PRL 2008

©npl.Washington.edu

MICROSCOPE satellite: 휂 푇푖, 푃푡 = −0.1 ± 1.3 × 10−14

Touboul et al, PRL 2017

©CNES, D. Ducros Simultaneous dual species interferometers

Suppresses time varying effects (mirror motion, laser phase, etc.)

Bragg Interferometer • Common Bragg laser beams • Common velocity selection • AC stark shift compensation

Phase shear readout Measure phase + contrast in one shot (Sugarbaker et al, PRL 2013) 10ħk Dual Species Run

Rb-85 and Rb-87 Rb-85 are in phase

2T = 1.8 s Rb-87 Detection

frequency

L (1 + h sin(ωt)) Megaparsecs… strain

Gravitational 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 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, , and white dwarf binaries Ultralight scalar dark matter discovery potential Early universe stochastic sources? (cosmic GW background) Sky position determination

Sky localization precision:

Mid-band advantages λ - Small wavelength λ - Long source lifetime (~months) maximizes effective R

R

Images: R. Hurt/Caltech-JPL; 2007 Thomson Higher Education Measurement Concept

Essential Features

1. Light propagates across the baseline at a constant speed

2. are good clocks

Atom Atom Clock Clock

L (1 + h sin(ωt)) Simple Example: Two Atomic Clocks

Atom Atom clock clock

Phase evolved by atom after time T

Time Simple Example: Two Atomic Clocks

GW changes light travel time

Time

Atom Atom clock clock Gradiometer sensor design

• Compare two (or more) atom ensembles g separated by a large baseline

• Science signal is differential phase between interferometers

• Differential measurement suppresses many sources of common noise and

Measurement Baseline Measurement systematic errors

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

Matter wave Atomic Gradiometer Interferometric Sensor

Source 1 50 meters 50

Source 2

100 meters 100 50 meters 50

Source 3

• 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 Stanford MAGIS prototype Sr gradiometer CAD Two assembled Sr atom sources (atom source detail)

Trapped Sr atom cloud (Blue MOT)

Atom optics laser (M Squared SolsTiS) Collaborators

Rb Atom Interferometry MAGIS-100: Mark Kasevich Joseph Lykken (Fermilab) Tim Kovachy Robert Plunkett (Fermilab) Chris Overstreet Swapan Chattopadhyay (Fermilab/NIU) Peter Asenbaum Jeremiah Mitchell (Fermilab) Remy Notermans Roni Harnik (Fermilab) Phil Adamson (Fermilab) Steve Geer (Fermilab) Jonathon Coleman (Liverpool) Sr Atom Interferometry TJ Wilkason Theory: Hunter Swan Peter Graham Jan Rudolph Savas Dimopoulos Yijun Jiang Surjeet Rajendran Ben Garber Asimina Arvanitaki Benjamin Spar Ken Van Tilburg Connor Holland