Optical Lattice Clock with Neutral Mercury

Transcription

1 Optical Lattice Clock with Neutral Mercury R. Tyumenev, Z. Xu, J.J. McFerran, Y. Le Coq and S. Bize SYRTE, Observatoire de Paris 61 avenue de l Observatoire, Paris, France rinat.tyumenev@obspm.fr Doctorale LNE July 2 nd, 2013 Observatoire de Meudon, France

2 Outline Basics of frequency standards Optical Clocks Optical lattice clocks with mercury Goals and Aims

3 Atoms as a reference Application Frequency Source Reference Servo System Low sensitivity to external perturbations High stability and accuracy Challenge: Black body radiation shift Cs, Rb, Sr, Sr +, Ca, Ca +, Yb, 2 Yb +, Mg, Hg, Hg +, Al +

4 Applications of highly accurate frequency standards Existing applications Realization of SI units (Second and Meter) and International Atomic Time (TAI) Search for physics beyond the Standard Model Study of Earth rotation (VLBI) Satellite navigation (GPS, GLONASS, GALILEO etc.) Telecommunications Future applications with higher precision Redefinition of SI second Existing applications with higher precision and extended frequency range New applications (clock-based geodesy)

5 From microwave to optical clocks Microwave clocks accuracy: Best optical clocks today: Al + 8,6*10-18 Ion in Paul trap: N=1 Neutrals: N>10 4

6 Optical lattice clocks Strong confinement Ultra-narrow carrier, mostly free of Doppler and recoil shifts 0.4 Transition probability Waist size 100 m! detuning [khz] Magic wavelength Linewidth = 3.2 Hz 3 P 0 H. Katori et al., Phys. Rev. Lett. 91, (2003) 1 S 0 No frequency shift due to lattice!

7 Optical lattice clocks with neutral mercury Why mercury? Low sensitivity to black body radiation (Sr/34) Good candidate for testing the stability of α - the fine structure constant 6 naturally abundant isotopes (2 fermions, 4 bosons) Hg (0.146%) Fermions have a clock transition with a linewidth of 100 mhz Low Doppler temperature on the 1 S 0-3 P 1 transition (T D ~ 30 μk) Fermions have low nuclear spin (1/2, 3/2) High vapor pressure at room temperature

8 Experiment scheme: UV light challenge Magneto Optical trap (MOT) T 30 K

9 Ultra stable laser source DFB Laser Inj.Lock ISO PP-MgO:SLT SHG BBO SHG AOM -180MHz 2 μw to Atoms Link to fountains OFC Linewidth 170 mhz Drift 20 mhz/s and Sr clocks lock J. Millo et al., Phys. Rev. A 79, (2009) S. Dawkins et al. Appl. Phys. B 99, 41 (2010) Yb fiber laser

10 Status of mercury lattice clock at LNE-SYRTE Lamb-Dicke spectroscopy of Hg Measurement of the magic wavelength Measured magic wavelength for Hg: ±0.0011nm L. Yi et al., Phys. Rev. Lett. 106, (2011) S. Mejri et al., Phys. Rev. A 84, (2011) Frequency stability: 5.4 x / τ Two optical cavities 5.4x10-15 / τ Hg transition lock Dick effect limit Absolute frequency measurement The measured frequency of the clock transition is: ± 6.4 (sys.) ± 0.3 (stat.) i.e. fractional uncertainty = 5.7 x Hg entered the BIPM List of Recommended Transitions at 2012 CCTF J. J. McFerran et al. Optics Letters, 37, 3477 (2012) J. J. McFerran et al., PRL 108,

11 Goals and aims Reach stability below at 1 second Accuracy down to <10-16 More reliable and powerful cooling laser source Have deeper lattice trap and stronger confinement

12 Preparation of the lattice trap with new cavity mirrors 362,5 nm Finesse 360 Twice tighter waist (69 m) 4 times deeper trap No coating degradation within 4 W travelling in the cavity Possibility to increase input power by renewing doubling stage Test in air Indium sealing Test in vacuum

13 254 nm laser source upgrade Cavity box design Mounting cavity with old crystal Implementing new 254 nm cavity on experiment. 508 nm 254nm 45 mw max operating power Each 2 hours crystal degradation Each 1,5 month OC degradation Stable operating at 50 mw No crystal or OC degradation Possibility to go up to 300 mw

14 To do Realign everything after big changes and get lattice trapped atoms Experiments with new lattice trap Deeper lattice trap, better MOT laser source 10 times more atoms, 100% contrast Measurement of systematic shifts at <10-16 level and down to in theory (magic wavelength) Measurement against Cs, Rb, Sr clocks

15 Thank you for your attention!