The Fermilab Holometer: Direct Laboratory Probes ofPlanck Scale Correlations in the Space-Time Vacuum

Ohkyung Kwon
University of Chicago • Holometer Collaboration

Cosmic Controversies Conference
October 6, 2019kwon@uchicago.edu

Cosmological constant as the energy of vacuum
G. Lemaître — PNAS 20, 12 (1934)
ASTRONOMY: G. LEMAITRE

12PROC. N. A. S

EVOLUTION OF THE EXPANDING UNIVERSE
By G. LEMAITRE
UNIVERSITY OF LouvAIN
Read before the Academy, Monday, November 20, 1933

The problem of the universe is essentially an application of the law ofgravitation to a region of extremely low density. The mean density ofmatter up to a distance of some ten millions of light years from us is of
the order of 10-30 gr./cm.3; if all the atoms of the stars were equallydistributed through space there would be about one atom per cubic yard,or the total energy would be that of an equilibrium radiation at the temperature of liquid hydrogen. The theory of relativity points out thepossibility of a modification of the law of gravitation under such extremeconditions. It suggests that, when we identify gravitational mass andenergy, we have to introduce a constant. Everything happens as though
the energy in zacuo would be different from zero. In order that absolutemotion, i.e., motion relative to vacuum, may not be detected, we must
associate a pressure p = - pc2 to the density of energy pC2 of vacuum.
This is essentially the meaning of the cosmical constant X which corresponds to a negative density of vacuum po according to'XC2(1)
10-27 gr./cm.3
47rG
Let us consider the motion of matter symmetrically distributed roundsome fixed point 0. The classical equation of motion under the action of
the modified gravitational field is2Gm +(2)Po = -GYa. B. Zel’dovich and A. Krasinski — Sov. Phys. Usp. 11, 381 (1968)
Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20192 / 22

The worst failed prediction in fundamental physics — a boundary condition?
Vacuum energy measured in a lab matches standard QFT.
If we scale this theory to the universe, prediction is 122 ordersof magnitude larger than the actual energy density.

Is a fine-tuned constant needed for cosmic structure?
Proposed explanations: multiverses, or a landscape?
The cosmological constant should be considered an
infrared boundary condition for the total degrees
of freedom in any fundamental theory of quantum
gravity, not a local contribution to the energy density.
[Tom Banks and Willy Fischler, arXiv:1811.00130]

Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20193 / 22

The holographic bound — infrared catastrophes in a definite background space-time
The entropy of a black hole — the amount of information in the system — is proportional tothe 2D “surface area” of its horizon. The information density decreases linearly with scale!

SBH =kA
4`2P

r=constant
IIIIIIn local QFT with a definite background,a system of scale R and cutoff m has totalmodes∼ R3 m3I

t=constantIVFor ΛQCD , gravitational binding energy
exceeded at a generalized Chandrasekhar
radius of 60 km — half of Lake Michigan!

RSAdS/CFT omits the degrees of freedom ina Planck resolution background space-time.
[A. Cohen, D. Kaplan, and A. Nelson, PRL 82, 4971] [T. Banks and W. Fischler, arXiv:1810.01671]
Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20194 / 22

Correlations in the space-time vacuum
Claim: Even the low-energy, ground-state limit of quantum gravity cannot be described byperturbative graviton fields on a background metric.
Scaling of information needs nonlocal correlations of space-time at large separations!

Can QFT accommodate the foundational principles needed in a fundamental theory?
Quantum Mechanics: No “local realistic” notions of classical geometrical paths and events
General Relativity: General covariance and background independence“Spukhafte” correlations (in the EPR sense) should exist in flat space-time with no dynamics.
Thermodynamic behavior of BH horizons applies to Unruh horizon entropy in accelerated frames.

Can we understand correlations in a space-time without a built-in boundary like AdS space?
Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20195 / 22

A new phenomenological regime

C. J. Hogan, arXiv:1412.1807
Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20196 / 22

The Fermilab Holometer
Holometer/MP8 Laser Lab

Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20197 / 22

The Fermilab Holometer

Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20197 / 22Extending LIGO technology to nonlocal correlations
LIGO −→ Holometer
Dick Gustafson (Michigan)
Samuel Waldman (SpaceX)
Rainer Weiss (MIT)

Laser interferometers: the most precise indifferential position measurements.
In dimensionless strain units h ≡ δL/L,
the power spectral density reachesqh̃2 (f ) . tP ≡ ~G/c5 ≈ 10−44 sec
LIGO measures local metric fluctuations
and stochastic gravitational waves.
Holometer probes similar stationary noisein space-time position, but at superluminal
frequencies sensitive to both spacelike andtimelike correlations across the system.

Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20198 / 22

Design principles
First-generation Holometer (2011 - 2016)

Cross-spectral density with two interferometers:´∞)h̃2 (f ) ≡ −∞ δLAL(t) δLB (t−τe−2πiτ f dτLt
Adopt model of delocalized Planckian fluctuations,each with a flat response over timescale L/c.
Variance scales like a random walk over L = 39 m:∆x2 P ≈ `P L ≈ PSD tP L2 × Bandwidth c/L
For shot noise limited PSD ≡ h̃2 (f ) · L2,h̃2 (f ) ≈ tP ≈ (N f )−1 ≈ 10−44 s

At f ≈ 1015 Hz, integrate over N ≈ 1029 photons!
The sampling rate and bandwidth must far exceed
the 7.7 MHz inverse light crossing time.

Isolated and independent: optics, vacuum systems, electronics, clocks, and data streams.
Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 20199 / 22

SpectralSpectral Density Ma

1010−40
10−41
10−42
10−43
10−4410−43

1st-gen Holometer: a verified symmetry at 0.2 Planckscale
10−351.0

Cross Powerag. part) [tP ]Cross Power(real part) [tP ]−3910−0.5
10−40
1.010−41−4210 0.5
10−43
0.0
10−44−0.5
1.00

Cross Power(imag. part) [tP ]Cross Power
Cross Power −1
SpectralDensity
Hz[tP ]
(imag. part)[tP ]Magnitude(real part)1010−36
0.5
10−370.0
10−38

Auto 1 Error (1σ + Sys.)
Auto 2 Error (1σ + Sys.)
Cross Error (1σ + Sys.)
Environmental Veto

Cross Power(real part) [tP ]Interferometer 1 AutoInterferometer 2 Auto
Interferometer 1, 2 Cross

12345Frequency [MHz]678−44

1.0
0.5
0.0
−0.5
1.0
0.5
0.0
−0.5
012345Frequency [MHz]678

Left: Independent bins at 1.9 kHz resolution.
Right: Rebinned to 100 kHz, Planck units.

0.5

145 hour data — PRL 117, 111102 (2016)

0.0704 hour data — CQG 34, 165005 (2017)−0.5
Instrumentation — CQG 34, 065005 (2017)
1.0

Serves as null control for 2nd-gen configuration.
0.50.0Ohkyung Kwon

Cross-power spectral density in δL/L, normalized
to L = 39 m, reaches an upper limit below 0.2 tP .

Light probes radial null (lightlike) paths to andfrom the beamsplitter measurements, in 2D.

Holometer • Cosmic Controversies

Oct 6, 201910 / 22

Two
TwoLayouts,
Layouts,Same
SameTechnique
Technique
The Holometer research programFirst-Generation
First-GenerationHolometer
HolometerFirst-generation
Holometer (2011 - 2016)(2012-2016)(2012-2016)

Second-Generation
Second-GenerationHolometer
Holometer

Second-generation(2017)
Holometer(2017) (2017-present)

90°90°armarmbendbend

Bendmirror added.
Unmodified:
optics, electronics, controlsystem,toanddata acquisition chain.
Sensitivity
Sensitivity
torotationalrotational
Sensitivity
Sensitivity
tototranslationaltranslational

fluctuations.
fluctuations.
Ohkyung Kwon

fluctuations.
fluctuations.

Holometer • Cosmic Controversies

Oct 6, 201911 / 22

What are the symmetries and degrees of freedom?
1st-gen Holometer — CQG 33, 105004 & 34, 075006 • E. Verlinde & K. Zurek, arXiv:1902.08207|dA/dτ|= |dA+ /dτ + dA− /dτ|,

Radial arms in two orthogonal directions from the beamsplitter.

a sum of the rotational components in the two directions, so that
(Ξ(τ) + constant) =P dA/cdτ.

All light propagation along null (lightlike) directions frommeasurements, following the boundary of a causal diamond.

τ), the swept area rate is simply related to the signal correlation by
PR

Poincaré symmetry

1/ 2tion to the exotic signal correlation at each
ined by closure of the circuit, is also ﬁxed by a projection onto the path, in thise (Eqs. 26, A13) :Lorentz boosts•2) + constant) = ∆ x ⊥R (τ) sinθ =Lorentz symmetry

TranslationsRotations

dA± /dτ = sin θdA± /dt = R (τ) sin
τ via dt/dτ

2nd-gen Holometer: Lorentz invariant models — CQG 34, 135006 & 35, 204001
Correlations respect exact causal structure (in radial directions from the observer’s world line)
Correlations must be along these surfaces: e.g. transverse ones with rotational symmetry
Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 201912 / 22

General hypothesis for future research program: “spooky” coherence on null surfaces
Light cones as coherent quantum objects

2 D quantum fluctuations(two transverse rotational axes)

1+1D fluctuations: Emergence of proper time
2D fluctuations: Emergence of local inertial frame
Decoherence happens on causal diamonds!
Dirac’s light cone function for relativistic quantum states

On light cone — “directional” eigenstates of proper timeτ̂i , τ̂j

= i ijk τ̂k tP

2-spheres

1+1 D quantum fluctuations

Hogan & Kwon,
CQG 35, 204001

Model of cosmological correlations:
Hogan, PRD 99, 063531 and arXiv:1908.07033
G. ’t Hooft’s model of black hole information — similar antipodal antisymmetric entanglement across the horizon
Found. Phys. 46: 1185, arXiv:1605.05119, Found. Phys. 48: 1134, arXiv:1804.05744, arXiv:1809.05367
Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 201913 / 22

Light cones as the basic quantum elements of space-time

Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.
“Just as the proper recognition of this atomicity requiresin the electromagnetic theory a modification in the useBbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.
of thefield concept
equivalent
to the introductionof theHolographic: Each spacelike 2-sphere hascorrelations
for two
independent
rotational axes.
concept of action at a distance, so it would appear thatt and τ via dt/dτ =insin
and the swept
via be able intheθ,gravitational
theory area
we should
principle to dispense with the concepts of space±/dτ = sin θdA± /dt = R(τ) sinθ,and time and take as the basis of our description(30)
of nature the elementary concepts of world line
n to the exotic signal correlation at eachτ, apart from a constant oset ﬁxed
and light cones.”

ed by closure of the circuit, is also ﬁxed by a projection onto the path, in this— J. A. Wheeler(Eqs. 26, A13) :1/ 2constant) = ∆ x 2⊥ R (τ) sinθ =P R(τ) sinθ.

(31)), the swept area rate is simply related to the signal correlation by

American Philosophical Society

Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 201914 / 22

2nd-gen Holometer: measuring angular rotation (1-axis) at Planck diffraction resolution!
Measuring the rotation of the Earth with light traveling in two directions around a loop.
Albert Michelson, winter 1924, suburban Chicago.

Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 201915 / 22

Preliminary
Second-generation Systematics:
Single Interferometer

Measured Sources of Environmental Noise

Correlated environmental noise measurements

Realtime Monitoring of Laser Noise andRadio-Frequency (RF) Environment

INPUT SIDE
Lasers & Active Optics• Correlated optical intensity noise• Correlated optical phase noiseContinuously measured during
data acquisition

OUTPUT SIDE
Detectors & Readout Electronics• Correlated electronics noise• Cross-channel signal leakage
Measured offline using opticalsources of independent white
noise (incandescent light bulbs)

Ohkyung
Kwon
Jonathan Richardson

Four RF environmental channels arecross-correlated with the interferometer
output channels (8x8 correlation matrix)

Holometer
Controversies
Nov.•17,Cosmic
2017 - FNAL
PAC

Oct 6, 201933

17 / 22

Preliminary
Second-generation Systematics:
Cross-interferometer

The cosmological constant (and other cosmic implications — inflationary signatures?)
Holographic correlations may reformulate Standard Model field vacuum
and determine its emergent gravity!
In causal diamonds of radius cτ0 , our posited holographic quantum system
would give an “emergent” localization ∼ ctP (τ0 /tP )1/3
In a system of size 1061 `P (cosmic horizon), an “emergent” localization
at the 1020 `P QCD scale — where QCD undergoes a phase change in thevacuum due to chiral symmetry breaking! We posit the kinematic effects offluctuating inertial frames to become “real” here, as virtual fields acquire mass.

The emergent “centrifugal” acceleration matches cosmic observations atexactly the 60 km generalized Chandrasekhar radius for ΛQCD !
Follows a numerical connection long-known since Zel’dovich (e.g. Bjorken, PRD 67, 043508)
Hogan, PRD 95: 104050 & arXiv:1804.00070 • Hogan & Kwon, CQG 35: 204001

Observable inflationary signatures: coherent quantum horizons with antipodal
antisymmetric entanglement — Hogan, PRD 99: 063531 & arXiv:1908.07033
Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 201921 / 22

Thanks to...

Ohkyung Kwon

Holometer • Cosmic Controversies

Oct 6, 201922 / 22

We hope to design and build a team for the next stage. Collaborate with us!