Matt Jones

Precision Tests of Fundamental Physics

using Strontium Clocks

Outline

1. Atomic clocks

2. The strontium lattice clock

3. Testing fundamental physics

4. 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 Counter

Feedback

Source: NIST

Ramsey interferometry

€

ψ = 12

0 + 1( )

€

ψ = 12

0 + ei(ω−ω0 )t 1( )

€

ψ =α 0 + β 1

€

ψ =0

split recombine

t

F=4

F=39.2 GHz

Ramsey interferometry

R. Wynands and S. Weyers, Metrologia 42 (2005) S64-S79

PTB

Doing better

•Higher Q

•No collisions€

Q =δωω

Trapped atoms

Optical transitions

Strontium lattice clock

1S0

1P1

461 nm = 32 MHz

3P 2

1

0

698 nm = 1 mHz

M. Takamoto et al., Nature 435, 321 (2005)

Magic lattices

•No Doppler shift

•Long interrogation times

•Reduced collisions

Optical clockwork

Oscillators:

Lasers need <1 Hz linewidth!

Ye group JILA

Counters:

Femtosecond frequency comb

(Nobel Prize 2005)

MPQ

/Bath University

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 α 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

€

δωSrωSR

= KrelSr δαα

€

δωCsωCs

= KrelCs + 2( )

δαα

+δμμ

Results

€

δα /α = (−3.1± 3.0)×10−16 / yr

δμ /μ = (1.5 ±1.7)×10−15 / 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 LaboratoriesUniversity of Nottingham

Panel sits tomorrow!!

Lattice clocks at Durham

Normalclock

Entangled clock€

ψN =12

0 + 1( ) ⎛ ⎝ ⎜

⎞ ⎠ ⎟N

€

ψN =12

01,02 ,K 0N + 11,12,K1N( )€

σ ∝1/ N

€

σ ∝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

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)

Optical clocksM. 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)