Microwave frequency standards are key to dissemination of high accuracy time services to UK science, technology and industry, and to compatibility with international timescales through world-wide time transfer and clock comparison.
Caesium fountain primary frequency standards are used to realise the SI definition of the second. NPL's caesium fountain (NPL-CsF2) is used to contribute to the international timescale UTC and is one of the most accurate in the world. It has also been used as the frequency reference for measurements of the absolute frequencies of optical clock transitions in ingle trapped strontium and ytterbium ions.
A second caesium fountain is being developed to enable the fountains to be validated at the highest accuracy levels and to enable continuous input into international timescales. NPL has also developed a rubidium fountain as a secondary representation of the second. These research activities are supported by work on low phase noise microwave local oscillators.
Compact microwave clocks are being developed for ultimate integration into hand-held and mobile frequency control and communcations equipment for applications within the defence, security and aerospace sectors. Our focus is on the development of 'chip-scale' coherent population trapping clocks based on MEMS on sealed hollow-core-fibre technology.
These research activities also feed into other areas such as atomic magnetometry.
Microwave Frequency Standards research
- COMSOL, Matlab and Mathematica sources codes, plus a few extras.
- Atomic frequency standards, high-stability oscillators and GPS-disciplined oscillators.