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, before joining NPL in 2008.  Since then, Rachel has been working in the area of optical atomic clocks.  Rachel is a Fellow of the Institute of Physics and represents NPL on the Consultative Committee for Time and Frequency as well as its Working Group on Primary and Secondary Frequency Standards.  She is currently the vice-chair of the Executive Committee for the European Frequency and Time Forum and also a vice-chair of its Scientific Committee. 

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 

Key publications

• ¹⁷¹Yb⁺ optical clock with 2.2 × 10^-18 systematic uncertainty and absolute frequency measurements 
  A. Tofful, C. F. A. Baynham, E. A. Curtis, A. O. Parsons, B. I. Robertson, M. Schioppo, J. Tunesi, H. S. Margolis, R. J. Hendricks, J. Whale, R. C. Thompson and R. M. Godun  
  Metrologia 61, 045001 (2024) 
• ¹⁷¹Yb⁺ ion optical clock at NPL: advances in automation and assessment of the trap-induced ac Zeeman shift in an endcap trap geometry 
  E. A. Curtis, A. Tofful, A. O. Parsons, B. I. Robertson and R. M. Godun  
  J. Phys.: Conf. Ser. 2889, 012044 (2024) 
• Analysis of atomic-clock data to constrain variations of fundamental constants 
  N. Sherrill, A. O. Parsons, C. F. A. Baynham, W. Bowden, E. A. Curtis, R. Hendricks, I. R. Hill, R. Hobson, H. S. Margolis, B. I. Robertson, M. Schioppo, K. Szymaniec, A. Tofful, J. Tunesi, R. M. Godun and X. Calmet. 
  New J. Phys. 25, 093012 (2023) 
• 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) 

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