Precision Tests of Fundamental Physics
using Strontium Clocks
Matt Jones
Outline
1.
2.
3.
4.
Atomic clocks
The strontium lattice clock
Testing fundamental physics
Entanglement and clocks
Atomic clocks
• The second
“The second is the duration of 9 192 631 770 periods of the radiation
corresponding to the transition between two hyperfine levels of the ground
state of the caesium 133 atoms (at 0K).”
• The metre:
“The metre is the length of the path travelled by light in vacuum during
a time interval of 1/299 792 458 of a second.”
Current accuracy: 1 × 10-15
Cs primary standard
Oscillator
Feedback
Source: NIST
Counter
Ramsey interferometry
F=4
9.2 GHz
F=3
t
recombine
split
  0
 
1
2



 0 
1 
1
0
2
e
i (    0 )t

1

  0 1
Ramsey interferometry
PTB
R. Wynands and S. Weyers, Metrologia 42 (2005) S64-S79
Doing better
•Higher Q
Q 

Trapped atoms

Optical transitions
•No
 collisions
Strontium lattice clock
1P
1
3P
461 nm
G/2p = 32 MHz
2
1
0
1S
0
698 nm
G/2p = 1 mHz
M. Takamoto et al., Nature 435, 321 (2005)
Magic lattices
•No Doppler shift
•Long interrogation times
•Reduced collisions
Optical clockwork
Lasers need <1 Hz linewidth!
Femtosecond frequency comb
(Nobel Prize 2005)
MPQ/Bath University
Counters:
Ye group JILA
Oscillators:
Optical atomic clocks
Courtesy of H. Margolis, NPL
Current state-of-the-art:
Single ions:
1 × 10-17
Lattice clocks: 1 × 10-16
C. W. Chou et al., quant-ph/0911.4572 (2010)
M. D. Swallow et al., quant-ph/1007.0059 (2010)
G. K. Campbell et al., Metrologia 45, 539 (2008)
Testing fundamental physics
•Relativity
10-16 is a difference in height of just 1m
•Time variation of fundamental constants
•Non-Newtonian short range forces
Time variation of fundamental constants
Motivation
•Cosmology
Some models predict that  and µ were different in the early universe
•Unified field theories
Constants couple to gravity
Implies a violation of Local Position Invariance
Principle
Measure how ωSr/ωCs varies with time
 Sr
 SR
 Cs


 Cs
 K rel
Sr



Cs
K rel

2





Results
 /   ( 3.1  3.0 )  10
 /   (1.5  1.7 )  10
 16
 15
/ yr
/ yr
Short-range forces
Do theories with compactified dimensions modify gravity at short range?
Lattice clocks at Durham
EPSRC proposal:
“Entanglement-enhanced enhanced optical frequency
metrology using Rydberg states”
Collaborators:
National Physical Laboratories
University of Nottingham
Panel sits tomorrow!!
Lattice clocks at Durham
Normal
clock
  1/ N
Entangled
clock 
  1/ N

N
N

 1
 
 0  1 
 2

N 
1
2
 0 1 , 0 2 ,K
0 N  11,1 2 ,K 1 N

Summary
•Atomic clocks provide the most accurate measurements
•Optical atomic clocks have lead to a new frontier
•This can be used for precision tests of our fundamental theories
References
Fountain clocks
R. Wynands and S. Weyers, Metrologia 42 (2005) S64-S79
Optical clocks
M. Takamoto et al., Nature 435, 321 (2009)
C. W. Chou et al., quant-ph/0911.4572 (2010)
M. D. Swallow et al., quant-ph/1007.0059 (2010)
G. K. Campbell et al., Metrologia 45, 539 (2008)
Fundamental physics tests
S. Blatt et al., Phys. Rev. Lett. 100, 140801 (2008)
P. Wolf et al., Phys. Rev. A 75, 063608 (2007)
F. Sorrentino et al., Phys. Rev. A 79, 013409 (2009)