Rachel Godun

Rachel Godun is the Science Area Leader for the optical frequency metrology group within Time & Frequency at NPL.  This includes optical clocks, ultrastable lasers, femtosecond frequency combs and time & frequency transfer over optical fibre links.  Rachel’s specialist area of research is the development of an optical atomic clock based on a trapped, single ion of ytterbium.  The research aims to make frequency measurements at the highest level of accuracy to support a future redefinition of the SI second and enable tests of fundamental physics.

Rachel graduated from the University of Oxford with an M.Phys. in 1997 and completed a D.Phil. in 2000, carrying out research in atom interferometry. She continued to work with ultra-cold atoms for a further 8 years in Oxford, first as a Junior Research Fellow at Christ Church and then as a Royal Society Dorothy Hodgkin Research Fellow.  Rachel joined NPL in 2008 and has been working since then in the area of optical atomic clocks.  Rachel is also a vice-chair of the Scientific Committee for the European Frequency and Time Forum, a technical expert for the European Metrology Network for Quantum Technologies and a member of the Institute of Physics.

Areas of interest

• Optical clocks and frequency metrology towards a redefinition of the SI second
• Precision measurements with optical clocks to test the fundamental laws of physics
• International frequency comparisons between optical clocks in different countries
• Robust optical clocks for future time scales and optical frequency services
• Recently coordinated a European joint research project to build optical clocks with 1 × 10⁻¹⁸ uncertainty, “OC18”.

Key publications

• Direct comparisons of European primary and secondary frequency standards via satellite techniques
  F. Riedel, A. Al-Masoudi, E. Benkler, S. Dörscher, V. Gerginov, C. Grebing, S. Häfner, N. Huntemann, B. Lipphardt, C. Lisdat, E. Peik, D. Piester, C. Sanner, C. Tamm, S. Weyers, H. Denker, L. Timmen, C. Voigt, D. Calonico, G. Cerretto, G. A. Costanzo, F. Levi, I. Sesia, J. Achkar, J. Guéna, M. Abgrall, D. Rovera, B. Chupin, C. Shi, S. Bilicki, E. Bookjans, J. Lodewyck, R. Le Targat, P. Delva, S. Bize, F. N. Baynes, C. F. A. Baynham, W. Bowden, P. Gill, R. M. Godun, I. R. Hill, R. Hobson, J. M. Jones, S. A. King, P. B. R. Nisbet-Jones, A. Rolland, S. L. Shemar, P. B. Whibberley and H. S. Margolis
  Metrologia 57, 045005 (2020)

• Search for transient variations of the fine structure constant and dark matter using fiber-linked optical atomic clocks
  B. M. Roberts, P. Delva, A. Al-Masoudi, A. Amy-Klein, C. Bærentsen, C. F. A. Baynham, E. Benkler, S. Bilicki, S. Bize, W. Bowden, J. Calvert, V. Cambier, E. Cantin, E. A. Curtis, S. Dörscher, M. Favier, F. Frank, P. Gill, R. M. Godun, G. Grosche, C. Guo, A. Hees, I. R. Hill, R. Hobson, N. Huntemann, J. Kronjäger, S. Koke, A. Kuhl, R. Lange, T. Legero, B. Lipphardt, C. Lisdat, J. Lodewyck, O. Lopez, H. S. Margolis, H. Álvarez-Martínez, F. Meynadier, F. Ozimek, E. Peik, P.-E. Pottie, N. Quintin, C. Sanner, L. De Sarlo, M. Schioppo, R. Schwarz, A. Silva, U. Sterr, Chr. Tamm, R. LeTargat, P. Tuckey, G. Vallet, T. Waterholter, D. Xu and P. Wolf
  New Journal of Physics 22, 093010 (2020)

• Absolute frequency measurement of the ²S_1/2 → ²F_7/2 optical clock transition in ¹⁷¹Yb⁺ with an uncertainty of 4 × 10⁻¹⁶ using a frequency link to international atomic time
  C. F. A. Baynham, R. M. Godun, J. M. Jones, S. A. King, P. B. R. Nisbet-Jones, F. Baynes, A. Rolland, P. E. G. Baird, K. Bongs, P. Gill and H. S. Margolis
  Journal of Modern Optics 65, 585 (2018)

• Frequency ratio of two optical clock transitions in ¹⁷¹Yb⁺ and constraints on the time variation of fundamental constants
  R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill
  Physical Review Letters 113, 210801 (2014)

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