Optical Atomic Clocks – Opening New Perspectives on the Quantum World

Jun Ye, JILA, NIST & University of Colorado 26th CGPM Open Session, November 16 2018

Cred

it: NIST

New physics on table top Many-body dynamics Quantum sensing Ultra-coherence

7 SI Base Units

m

cd

mol

K

A

s

kg

e

133Cs

NA

C kB

h Kcd

Almost all units, base or derived, can be traced to time

• Fundamental laws & constants are our units

• “For all times, For all people.” • “For all times, For all people.”

Probes for Fundamental Physics

Network of clocks (10-21): long baseline interferometry

Standard Model SI units But, it is INCOMPLETE : • Dark matter & energy • Matter-antimatter asymmetry

Space-time ripples Unruly spiral galaxies Dark matter halo

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it: NA

SA

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it: NA

SA

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it: NA

SA

Kolkowitz et al., Phys. Rev. D 94, 124043 (2016).

Kómár et al., Nat. Phys. 10, 582 (2014);

Time Scales C

redit: N

ASA

Life of the Universe: 15 billion years (1018 s） 1,000,000,000,000,000,000 seconds

Quantum pendulum period: 10-15 s 0.000 000 000 000 001 second

The geometric mean ~30 s

Sr atoms:

• 1S0 ↔ 3P0 (160 s)

• Q ~ 1017

Quantum Certainty and Uncertainty

|g>

|e>

Quantized transition frequency

12

3 9 10

11

8 7

1 2

4

5 6

|e>

|g>

1

2𝑒𝑖𝜙|𝑒 + |𝑔

The Strength of MANY – when you are certain

12

3 9

10 11

8 7

1 2

4

5 6

Quantum Phase Noise of Atoms Classical Phase Noise of Probe Laser

DfSQL =1

NradQuantization of Motion & Interaction

(Quantum Certainty)

Optical Coherence time ~ 1 minute

JILA

PTB

Matei et al., PRL 118, 263202 (2017); Zhang et al., PRL 119, 243601 (2017).

Sign

al a

mp

litu

de

0

0.1

0.2

0.3

0.4

0.5

Beat frequency (Hz)

0 0.10 0.05 -0.10 -0.05

Stability: 4 x 10-17

A ruler for the Universe

Laser is the Central Ruler of Time & Space

Hänsch & Hall: Frequency comb

Cooling Atoms with Light Chu, Cohen-Tannoudji, Phillips

Holding Atoms in a Magic Light Bowl Ye, Kimble, Katori, Science 320, 1734 (2008).

|g>

|e>

698 nm

87Sr

Incident laser

g

e

Laser beam

Udipole Clock laser

Ashkin, …

|g> |e>

Quantizing the Doppler Effect Kolkowitz et al., Nature 542, 66 (2017).

T = 1 mK

Quantum State Control

• Doppler shift = 0 (motion quantized)

• Precision improvement by N1/2

|g>

trapω

|e>

Ludlow et al., Rev. Mod. Phys. 87, 647 (2015).

JILA Sr Clock II : 2.1 x 10-18

Nicholson et al., Nature Comm. 6 (2015).

-15 -10 -5 0 5 10 150

0.2

0.4

0.6

0.8

Detuning (Hz)

Exc

itatio

n F

ract

ion

Linewidth ~ Hz

Haroche, Wineland

Atomic Clock: Sensors of Space-time

10-20

Nicholson et al., Nature Comm. 6 (2015). Sr: t ~ 160 s Q ~ 1017

Poli et al. La rivista del Nuovo Cimento, 36, 555 (2013).

Quantization along x & y

3D Fermi Gas Clock

Scaling up the Sr quantum clock:

1 million atoms (100 x 100 x 100 cells)

Pauli Exclusion Principle

1 atom (clock) per site

Coherence 160 s

Precision 3 x 10-20 Hz-1/2

Quantum gases: Cornell, Ketterle, Wieman; Jin

A Fermi Gas Mott Insulator Clock

0 0 0

𝑥 𝑦 𝑧

Clock laser frequency (kHz) Ex

cita

tio

n f

ract

ion

Nuclear spin 9/2

|g>

|e>

Goban et al., Nature 563, 369 – 373 (2018).

Interaction quantized

Long Atom-Light Coherence S. Campbell et al., Science 358, 90 (2017).

Quality factor: 8 x 1015

Atom-Light coherence: 10 s

Laser detuning (Hz)

Exci

tati

on

fra

ctio

n

6s, 83 mHz

Limit: photon scattering ; need shallow lattices

A Fermi Band/Mott Insulator Clock

Change the interference angle q , but need to have 𝛿𝜃 < 3𝑜 × 10−5

𝑎 =

Lattice spacing = 813 nm / 2sin(𝜃/2)

lclock

Kolkowitz et al., Nature 542, 66 (2017); Bromley et al., Nature Phys. 14, 399 (2018).

t

lclock

t

𝑒𝑖2𝜋 𝑎/𝜆𝑐𝑙𝑜𝑐𝑘 = 1 𝑒𝑖2𝜋 𝑎/𝜆𝑐𝑙𝑜𝑐𝑘 ≠ 1

Clock under a Microscope

Imaging resolution ≈ 1 μm ≈ 2 lattice sites

Marti et al., Phys Rev Lett 120, 103201 (2018).

𝛻𝐵𝑥 10-19

10-18

10-17

102 104 103 10 Average time (s)

Alla

n D

evia

tio

n 2.5⨉10-19

@ 3 hours

Quality factor 8 x 1015

Gravitational Potential & Atomic Coherence

Extreme spatial resolution & precision

GR entangles a clock with its spatial degrees of freedom via time dilation

Spatial coherence modulated due to which-way information

Unexplored regime: quantum dynamics with post-Newtonian effects.

10 μm height: 10-21 effect

E. Marti (Stanford U) S. Bromley (U. Durham) W. Zhang (NIST) S. Campbell (UC Berkeley) S. Kolkowitz (U. Wisconsin) X. Zhang (Peking U.) T. Nicholson (NUS) M. Bishof (Argonne) B. Bloom (Atom Compute) M. Martin (Los Alamos) J. Williams (JPL/Caltech) M. Swallows (Honeywell) S. Blatt (MPQ, Garching)

A. Ludlow (NIST) G. Campbell (JQI, NIST) T. Zelevinsky (Columbia U.) Y. Lin (NIM) M. Boyd (AO Sense) J. Thomsen (U. Copenhagen) T. Zanon (Univ. Paris 6) S. Foreman (U. San Fran) X. Huang (WIPM) T. Ido (NICT Tokyo) X. Xu (ECNU) T. Loftus (Honeywell)

T. Bothwell D. Kedar C. Kennedy W. Milner E. Oelker J. Robinson

A. Goban R. Hutson C. Sanner L. Sonderhouse

Collaboration: NIST Time & Frequency, PTB (Riehle, Sterr, Legero) Theory: A. M. Rey, M. Safronova, P. Julienne, M. Lukin, P. Zoller, …

Sr optical clock – a big playground Current Sr Group

Laser is the Central Ruler of Time & Space

Length is linked to Time via c

0 1 2 3 4 5

Inte

nsi

ty

Time (ns)

Laser CavityCavity length L ~ 1 m DL ~ 10-16 m (size of a nucleus: 10-14 m)

0 1 2 3 4 5

Intensity

Time (ns)

Laser Cavity

Hänsch & Hall: Optical frequency comb

Clock Meets Atomic Interactions

U t >> 1

Quantum fluctuations correlated

Martin et al., Science 341, 632 (2013). Zhang et al., Science 345, 1467 (2014).

U

U

Frac

tio

nal

Sh

ift

(10

-15)

Excitation angle

-2

-1

1

0

× |↑↓ + |↓↑

|n1 n2 ‒ |n2 n1

ni

nj

Table-top search for new physics Many-body dynamics Quantum sensing

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it: Ye Gro

up

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it: NIST

Cred

it: Ye Gro

up

Atomic Clock: Sensors of Space-time

Important innovations: Higher Q optical transitions New laser phase control: optical coherence > 1 s Trapped atoms/ions: high N, long coherence Optical frequency comb

10-20

Nicholson et al., Nature Comm. 6 (2015).

Current accuracy ~10-18 : gravitational redshift 1 cm

Quantum many-body and coherence

Sr: t ~ 160 s Q ~ 1017

Poli et al. La rivista del Nuovo Cimento, 36, 555 (2013).

Quantization along x & y