Time, Frequency & the Metre
The 2006 - 2009 TFM programme is an amalgamation of the former NMS Time programme and projects from Theme 1 of the former NMS Length programme. This reflects a change of emphasis in optical frequency metrology from providing traceability for length (which it will continue to do) to the long-term development of an optical redefinition of the SI second.
This trend is reflected in the new TFM programme by a shift in effort from research and development into microwave fountains (which realise the current primary frequency standard) to the development of clocks based on a long-lived optical transition in a single trapped ultra-cold ion. In addition, the programme will for the first time start work on the development of a novel optical frequency standard based on a lattice of cold atoms that is predicted to have stabilities well beyond what can presently be achieved. These projects should ensure that the NMS plays a significant role in informing the international discussions regarding the SI second redefinition.
Timescale realisation and dissemination includes the production of the UK timescale UTC(NPL), the development of international time transfer techniques, and the broadcast of the MSF standard frequency and time signal on 60 kHz. A significant part of the programme is directed to support the development of the European satellite navigation system, Galileo, which will become operational during the course of the programme.
Optical frequency dissemination will be a core activity within the new programme. Frequency metrology has changed dramatically during the last decade since the development of the femtosecond frequency comb, and the new programme aims to fully exploit its properties and applications. The programme will also provide laser frequency and interferometer calibration services to the telecommunications and dimensional metrology industries.
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