Geodesy and metrology with a transportable optical clock

Abstract

Optical atomic clocks, due to their unprecedented stability1,2,3 and uncertainty3,4,5,6, are already being used to test physical theories7,8 and herald a revision of the International System of Units9,10. However, to unlock their potential for cross-disciplinary applications such as relativistic geodesy11, a major challenge remains: their transformation from highly specialized instruments restricted to national metrology laboratories into flexible devices deployable in different locations12,13,14. Here, we report the first field measurement campaign with a transportable 87Sr optical lattice clock12. We use it to determine the gravity potential difference between the middle of a mountain and a location 90 km away, exploiting both local and remote clock comparisons to eliminate potential clock errors. A local comparison with a 171Yb lattice clock15 also serves as an important check on the international consistency of independently developed optical clocks. This campaign demonstrates the exciting prospects for transportable optical clocks.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Schematic representation of the measurement campaign.
Fig. 2: Instability of the measured fractional Yb/Sr frequency ratio R/R0.
Fig. 3: Comparison of frequency ratios R between 171Yb and 87Sr lattice clocks.

References

  1. 1.

    Schioppo, M. et al. Ultra-stable optical clock with two cold-atom ensembles. Nat. Photon. 11, 48–52 (2017).

    ADS  Article  Google Scholar 

  2. 2.

    Al-Masoudi, A., Dörscher, S., Häfner, S., Sterr, U. & Lisdat, C. Noise and instability of an optical lattice clock. Phys. Rev. A 92, 063814 (2015).

    ADS  Article  Google Scholar 

  3. 3.

    Nicholson, T. L. et al. Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty. Nat. Commun. 6, 6896 (2015).

    Article  Google Scholar 

  4. 4.

    Ushijima, I., Takamoto, M., Das, M., Ohkubo, T. & Katori, H. Cryogenic optical lattice clocks. Nat. Photon. 9, 185–189 (2015).

    ADS  Article  Google Scholar 

  5. 5.

    Huntemann, N., Sanner, C., Lipphardt, B., Tamm, C. & Peik, E. Single-ion atomic clock with 3 × 10−18 systematic uncertainty. Phys. Rev. Lett. 116, 063001 (2016).

    ADS  Article  Google Scholar 

  6. 6.

    Chou, C. W., Hume, D. B., Koelemeij, J. C. J., Wineland, D. J. & Rosenband, T. Frequency comparison of two high-accuracy Al+ optical clocks. Phys. Rev. Lett. 104, 070802 (2010).

    ADS  Article  Google Scholar 

  7. 7.

    Huntemann, N. et al. Improved limit on a temporal variation of m p/m e from comparisons of Yb+ and Cs atomic clocks. Phys. Rev. Lett. 113, 210802 (2014).

    ADS  Article  Google Scholar 

  8. 8.

    Godun, R. M. et al. Frequency ratio of two optical clock transitions in 171Yb+ and constraints on the time-variation of fundamental constants. Phys. Rev. Lett. 113, 210801 (2014).

    ADS  Article  Google Scholar 

  9. 9.

    Riehle, F. Towards a redefinition of the second based on optical atomic clocks. C. R. Phys. 16, 506–515 (2015).

    Article  Google Scholar 

  10. 10.

    Margolis, H. Timekeepers of the future. Nat. Phys. 10, 82–83 (2014).

    Article  Google Scholar 

  11. 11.

    Vermeer, M. Chronometric levelling. Rep. Finn. Geod. Inst. 83, 2 (1983).

    Google Scholar 

  12. 12.

    Koller, S. B. et al. Transportable optical lattice clock with 7 × 10−17 uncertainty. Phys. Rev. Lett. 118, 073601 (2017).

    ADS  Article  Google Scholar 

  13. 13.

    Cao, J. et al. A transportable 40Ca+ single-ion clock with 7.7 × 10−17 systematic uncertainty. Appl. Phys. B 123, 112 (2017).

    ADS  Article  Google Scholar 

  14. 14.

    Bongs, K. et al. Development of a strontium optical lattice clock for the SOC mission on the ISS. C. R. Phys. 16, 553–564 (2015).

    Article  Google Scholar 

  15. 15.

    Pizzocaro, M. et al. Absolute frequency measurement of the 1S03P0 transition of 171Yb. Metrologia 54, 102–112 (2017).

    ADS  Article  Google Scholar 

  16. 16.

    Denker, H. in Sciences of Geodesy – II (ed. Xu, G.) Ch. 5 (Springer, 2013).

  17. 17.

    Lisdat, C. et al. A clock network for geodesy and fundamental science. Nat. Commun. 7, 12443 (2016).

    ADS  Article  Google Scholar 

  18. 18.

    Calonico, D. et al. High-accuracy coherent optical frequency transfer over a doubled 642-km fiber link. Appl. Phys. B 117, 979–986 (2014).

    ADS  Article  Google Scholar 

  19. 19.

    Takano, T. et al. Geopotential measurements with synchronously linked optical lattice clocks. Nat. Photon. 10, 662–666 (2016).

    ADS  Article  Google Scholar 

  20. 20.

    Barwood, G. P. et al. Agreement between two 88Sr+ optical clocks to 4 parts in 1017. Phys. Rev. A 89, 050501 (2014).

    ADS  Article  Google Scholar 

  21. 21.

    Vogt, S. et al. A transportable optical lattice clock. J. Phys. Conf. Ser. 723, 012020 (2016).

    Article  Google Scholar 

  22. 22.

    Leibrandt, D. R., Bergquist, J. C. & Rosenband, T. Cavity-stabilized laser with acceleration sensitivity below 10−12 g−1. Phys. Rev. A 87, 023829 (2013).

    ADS  Article  Google Scholar 

  23. 23.

    Levi, F. et al. Accuracy evaluation of ITCsF2: a nitrogen cooled caesium fountain. Metrologia 51, 270 (2014).

    ADS  Article  Google Scholar 

  24. 24.

    Grebing, C. et al. Realization of a timescale with an accurate optical lattice clock. Optica 3, 563–569 (2016).

    Article  Google Scholar 

  25. 25.

    Margolis, H. S. & Gill, P. Least-squares analysis of clock frequency comparison data to deduce optimized frequency and frequency ratio values. Metrologia 52, 628–634 (2015).

    ADS  Article  Google Scholar 

  26. 26.

    Report of the 104 th Meeting of the Comité International des Poids et Mesures (CIPM) (BIPM, 2015).

  27. 27.

    Nemitz, N. et al. Frequency ratio of Yb and Sr clocks with 5 × 10−17 uncertainty at 150 s averaging time. Nat. Photon-. 10, 258–261 (2016).

    ADS  Article  Google Scholar 

  28. 28.

    Takamoto, M. et al. Frequency ratios of Sr, Yb, and Hg based optical lattice clocks and their applications. C. R. Phys. 16, 489–498 (2015).

    Article  Google Scholar 

  29. 29.

    Akamatsu, D. et al. Frequency ratio measurement of 171Yb and 87Sr optical lattice clocks. Opt. Express 22, 7898–7905 (2014); erratum 22, 32199–32199 (2014).

  30. 30.

    Grosche, G. Eavesdropping time and frequency: phase noise cancellation along a time-varying path, such as an optical fiber. Opt. Lett. 39, 2545–2548 (2014).

    ADS  Article  Google Scholar 

  31. 31.

    Katori, H., Takamoto, M., Pal’chikov, V. G. & Ovsiannikov, V. D. Ultrastable optical clock with neutral atoms in an engineered light shift trap. Phys. Rev. Lett. 91, 173005 (2003).

    ADS  Article  Google Scholar 

  32. 32.

    Blatt, S. et al. Rabi spectroscopy and excitation inhomogeneity in a one-dimensional optical lattice clock. Phys. Rev. A 80, 052703 (2009).

    ADS  Article  Google Scholar 

  33. 33.

    Westergaard, P. G. et al. Lattice-induced frequency shifts in Sr optical lattice clocks at the 10−17 level. Phys. Rev. Lett. 106, 210801 (2011).

    ADS  Article  Google Scholar 

  34. 34.

    Middelmann, T., Falke, S., Lisdat, C. & Sterr, U. High accuracy correction of blackbody radiation shift in an optical lattice clock. Phys. Rev. Lett. 109, 263004 (2012).

    ADS  Article  Google Scholar 

  35. 35.

    Safronova, M. S., Porsev, S. G., Safronova, S. U., Kozlov, M. G. & Clark, C. W. Blackbody radiation shift in the Sr optical atomic clock. Phys. Rev. A 87, 012509 (2013).

    ADS  Article  Google Scholar 

  36. 36.

    Sherman, J. A. et al. High accuracy measure of atomic polarizability in an optical lattice clock. Phys. Rev. Lett. 108, 153002 (2012).

    ADS  Article  Google Scholar 

  37. 37.

    JCGM (BIPM, IEC, IFCC, ILAC, ISO, IUPAC, IUPAP and OIML) Evaluation of Measurement DataGuide to the Expression of Uncertainty in Measurement Vol. 100 (International Organization for Standardization, 2008); http://www.bipm.org/utils/common/documents/jcgm/JCGM_100_2008_E.pdf

  38. 38.

    Voigt, C., Denker, H. & Timmen, L. Time-variable gravity potential components for optical clock comparisons and the definition of international time scales. Metrologia 53, 1365–1383 (2016).

    ADS  Article  Google Scholar 

  39. 39.

    Denker, H. et al. Geodetic methods to determine the relativistic redshift at the level of 10–18 in the context of international timescales—a review and practical results. J. Geod. https://doi.org/10.1007/s00190-017-1075-1 (2017).

    Google Scholar 

  40. 40.

    Torge, W. & Müller, J. Geodesy 4th edn (De Gruyter, 2012).

  41. 41.

    European Metrology Research Programme Project SIB-55 International Timescales with Optical Clocks (2016); http://projects.npl.co.uk/itoc/project-structure/reg/gravity-observations/

  42. 42.

    Mayer-Gürr, T. et al. The combined satellite gravity field model GOCO05s. Geophys. Res. Abstracts 17, EGU2015–12364 (2015).

    Google Scholar 

  43. 43.

    Barzaghi, R. et al. Orthometric correction and normal heights for Italian levelling network: a case study. Appl. Geomat. 6, 17–25 (2014).

    Article  Google Scholar 

  44. 44.

    Stenger, J., Schnatz, H., Tamm, C. & Telle, H. R. Ultra-precise measurement of optical frequency ratios. Phys. Rev. Lett. 88, 073601 (2002).

    ADS  Article  Google Scholar 

  45. 45.

    Cox, M. G., Eiø, C., Mana, G. & Pennecchi, F. The generalized weighted mean of correlated quantities. Metrologia 43, S268 (2006).

    ADS  Article  Google Scholar 

  46. 46.

    Boyd, M. M. et al. 87Sr lattice clock with inaccuracy below 10−15. Phys. Rev. Lett. 98, 083002 (2007).

    ADS  Article  Google Scholar 

  47. 47.

    Baillard, X. et al. An optical lattice clock with spin-polarized 87Sr atoms. Eur. Phys. J. D. 48, 11–17 (2008).

    ADS  Article  Google Scholar 

  48. 48.

    Campbell, G. K. et al. The absolute frequency of the 87Sr optical clock transition. Metrologia 45, 539–548 (2008).

    ADS  Article  Google Scholar 

  49. 49.

    Hong, F.-L. et al. Measuring the frequency of a Sr optical lattice clock using a 120 km coherent optical transfer. Opt. Lett. 34, 692–694 (2009).

    ADS  Article  Google Scholar 

  50. 50.

    Falke, S. et al. The 87Sr optical frequency standard at PTB. Metrologia 48, 399–407 (2011).

    ADS  Article  Google Scholar 

  51. 51.

    Yamaguchi, A. et al. Stability transfer between two clock lasers operating at different wavelengths for absolute frequency measurement of clock transition in 87Sr. Appl. Phys. Express 5, 022701 (2012).

    ADS  Article  Google Scholar 

  52. 52.

    Matsubara, K. et al. Direct comparison of a Ca+ single-ion clock against a Sr lattice clock to verify the absolute frequency measurement. Opt. Express 20, 22034–22041 (2012).

    ADS  Article  Google Scholar 

  53. 53.

    Le Targat, R. et al. Experimental realization of an optical second with strontium lattice clocks. Nat. Commun. 4, 2109 (2013).

    Google Scholar 

  54. 54.

    Falke, S. et al. A strontium lattice clock with 3 × 10−17 inaccuracy and its frequency. New J. Phys. 16, 073023 (2014).

    ADS  Article  Google Scholar 

  55. 55.

    Akamatsu, D. et al. Spectroscopy and frequency measurement of the 87Sr clock transition by laser linewidth transfer using an optical frequency comb. Appl. Phys. Express 7, 012401 (2014).

    ADS  Article  Google Scholar 

  56. 56.

    Hachisu, H. et al. Direct comparison of optical lattice clocks with an intercontinental baseline of 9000 km. Opt. Lett. 39, 4072–4075 (2014).

    ADS  Article  Google Scholar 

  57. 57.

    Lin, Y.-G. et al. First evaluation and frequency measurement of the strontium optical lattice clock at NIM. Chin. Phys. Lett. 32, 090601 (2015).

    ADS  Article  Google Scholar 

  58. 58.

    Tanabe, T. et al. Improved frequency measurement of the 1S03P0 clock transition in 87Sr using a Cs fountain clock as a transfer oscillator. J. Phys. Soc. Jpn. 84, 115002 (2015).

    ADS  Article  Google Scholar 

  59. 59.

    Lodewyck, J. et al. Optical to microwave clock frequency ratios with a nearly continuous strontium optical lattice clock. Metrologia 53, 1123 (2016).

    ADS  Article  Google Scholar 

  60. 60.

    Hachisu, H., Petit, G. & Ido, T. Absolute frequency measurement with uncertainty below 1 × 10−15 using International Atomic Time. Appl. Phys. B 123, 34 (2017).

    ADS  Article  Google Scholar 

  61. 61.

    Hachisu, H., Petit, G., Nakagawa, F., Hanado, Y. & Ido, T. SI-traceable measurement of an optical frequency at the low 10−16 level without a local primary standard. Opt. Express 25, 8511–8523 (2017).

    ADS  Article  Google Scholar 

  62. 62.

    Kohno, T. et al. One-dimensional optical lattice clock with a fermionic 171Yb isotope. Appl. Phys. Express 2, 072501 (2009).

    ADS  Article  Google Scholar 

  63. 63.

    Lemke, N. D. et al. Spin-1/2 optical lattice clock. Phys. Rev. Lett. 103, 063001 (2009).

    ADS  Article  Google Scholar 

  64. 64.

    Yasuda, M. et al. Improved absolute frequency measurement of the 171Yb optical lattice clock towards a candidate for the redefinition of the second. Appl. Phys. Express 5, 102401 (2012).

    ADS  Article  Google Scholar 

  65. 65.

    Park, C. Y. et al. Absolute frequency measurement of 1S0 (F = 1/2) mm–3P0 (F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS. Metrologia 50, 119–128 (2013).

    ADS  Article  Google Scholar 

  66. 66.

    Kim, H. et al. Improved absolute frequency measurement of the 171Yb optical lattice clock at KRISS relative to the SI second. Jpn J. Appl. Phys. 56, 050302 (2017).

    ADS  Article  Google Scholar 

Download references

Acknowledgements

We would like to thank T. Zampieri for his technical support at LSM and A. Mura and Consorzio TOP-IX for technical help in the access to the optical fibre. The authors acknowledge funding from European Metrology Research Program (EMRP) Project SIB55 ITOC, the EU Innovative Training Network (ITN) Future Atomic Clock Technology (FACT), the DFG funded CRC 1128 geo-Q (Projects A03 and C04) and RTG 1728 and the UK National Measurement System Quantum, Electromagnetics and Time Programme. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.

Author information

Affiliations

Authors

Contributions

D.C. coordinated the measurement campaign with contributions from C.L., H.S.M. and Mi.Z.; J.G., S.K., S.V., S.H., U.S. and C.L. designed, built and operated the transportable Sr lattice clock; H.D., C.V. and L.T. made the geodetic measurements and calculated the local gravity potential values; A.R., F.N.B. and H.S.M. prepared, characterized and operated the transportable frequency comb; M.P., P.T., B.R., F.B., and D.C. designed, built and operated the Yb lattice clock; G.A.C. and F.L. designed, built and operated the INRIM Cs fountain, C.C. and A.T. designed, characterized and operated the optical fibre link between INRIM and LSM; C.C., P.B. and Ma.Z. operated the frequency comb at INRIM. J.G., C.C., M.P., F.L., A.R., F.N.B., H.S.M., S.K. and C.L. contributed to the data analysis for the ratio and absolute frequency measurement. C.L. wrote the paper with support from H.S.M. and D.C. All authors discussed the results and commented on the paper.

Corresponding author

Correspondence to Christian Lisdat.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Grotti, J., Koller, S., Vogt, S. et al. Geodesy and metrology with a transportable optical clock. Nature Phys 14, 437–441 (2018). https://doi.org/10.1038/s41567-017-0042-3

Download citation

Further reading