matt jones
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Matt Jones
Precision Tests of Fundamental Physics using Strontium Clocks
Outline
1. Atomic clocks2. The strontium lattice clock3. Testing fundamental physics4. 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 clocksR. 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)
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