Hugh Klein

Hugh Klein joined NPL in 1987 as a senior scientist and was promoted to principal scientist in 1990. Recently he has been working on the development of microwave clock prototypes.

From 2015-18 he was technical lead of a “Ytterbium (Yb⁺) microwave clock” project; a 6U 19-inch rack laboratory demonstrator achieved a stability of 10^-13 at 1000 seconds. An Innovate UK “Synchronicity” project followed - a collaboration between Te2v and NPL - which looked at the feasibility of developing a commercial Yb⁺ microwave standard. Previously he was lead scientist of the “Trapped Ion Optical Frequency Standards” project, with experimental activity focusing on a Sr⁺. In 1993 Hugh worked on a strategic research project on Yb⁺, which observed an optical octupole transition to a state with a ten-year lifetime. From 1997-2002, he was deputy research director of a UK-Japan project on "Cold Trapped Ions" and from 1999-2002 he led the UK side of a UK-China trapped ion project. Hugh was at Harvard University from 1984-87 as a research associate working on fast-beam microwave He⁺ Lamb shift spectroscopy. He was a research assistant at the University of Oxford from1983-84. Qualifications: MBA (LBS); DPhil (University of Oxford); BSc (Imperial College).

Areas of interest:

• Currently focused on optical and microwave based frequency standards. Trapped ion optical clocks have potential space applications for improved navigation and tests of fundamental physics, and are also a possible candidate for the redefinition of the second. There is industrial interest in developing compact, portable microwave clocks.
• Precise spectroscopy of hydrogen leading to a measurement of the Rydberg constant and a determination of the size of the proton.

Key Publications

• Laser-cooled ytterbium-ion microwave frequency standard. 
  S. Mulholland, H. A. Klein, G. P. Barwood, S. Donnellan, D. Gentle, G. Huang, G. Walsh, P. E. G. Baird and P. Gill
  Applied Physics B, 125 198 (2019)
• Agreement between two ⁸⁸Sr⁺ optical clocks to 4 parts in 10¹⁷ 
  G. P. Barwood, G. Huang, H. A. Klein, L. A. M. Johnson, S.A. King, H.S. Margolis, K. Szymaniec and P. Gill
  Phys. Rev. A, 89 (5) 050501 (2014)
• Observation of an electric octupole transition in a single Ion. 
  M. Roberts, P. Taylor, G. P. Barwood, P. Gill, H.A. Klein, and W. R. C. Rowley
  Phys. Rev. Lett., 78 (10) 1876 (1997)
• Laser-Induced M1 Resonance Spectroscopy of the 1s2p³P₁-³P₂ Fine Structure of ¹⁹F⁷⁺ 
  E. G. Myers, P. Kuske, H. J. Andrä, I. A. Armour, N. A. Jelley, H. A. Klein, J. D. Silver, and E. Träbert,
  Phys. Rev. Lett. 47 1419 (1981)

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