1. Matt Jones Precision Tests of Fundamental Physics using Strontium Clocks

2. Outline 1.Atomic clocks 2.The strontium lattice clock 3.Testing fundamental physics 4.Entanglement and clocks

3. 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

4. Cs primary standard OscillatorCounter Feedback Source: NIST

5. Ramsey interferometry split recombine t F=4 F=3 9.2 GHz

6. Ramsey interferometry R. Wynands and S. Weyers, Metrologia 42 (2005) S64-S79 PTB

7. Doing better Higher Q No collisions Trapped atoms Optical transitions

8. Strontium lattice clock 1S01S0 1P11P1 461 nm  = 32 MHz 3P3P 2 1 0 698 nm  = 1 mHz M. Takamoto et al., Nature 435, 321 (2005)

9. Magic lattices No Doppler shift Long interrogation times Reduced collisions

10. Optical clockwork Oscillators: Lasers need <1 Hz linewidth! Ye group JILA Counters: Femtosecond frequency comb (Nobel Prize 2005) MPQ/Bath University

11. 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)

12. Testing fundamental physics Relativity 10 -16 is a difference in height of just 1m Time variation of fundamental constants Non-Newtonian short range forces

13. Time variation of fundamental constants

14. 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

15. Principle Measure how ω Sr /ω Cs varies with time

16. Results

17. Short-range forces Do theories with compactified dimensions modify gravity at short range?

18. 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!!

19. Lattice clocks at Durham Normal clock Entangled clock

20. 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

21. 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 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)