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
Cred
it: NA
SA
Cred
it: NA
SA
Cred
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
Cred
it: Ye Gro
up
Cred
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