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The Pathfinder Metrology programme supports the International System of Units (SI) and has the following objectives:
• To make available the SI base units at the greatest possible accuracy, and to maintain the integrity of the links between the SI units;
• To research novel techniques and technologies that have the potential to make significant improvements to the NMS;
The programme takes a medium to long term view, up to 10 - 15 years ahead, and concentrates on research and development. The long term goal is to devise universal measurement standards based wholly on fundamental constants and quantum processes, thereby avoiding reliance on physical artefacts.
The work is organised in four themes:
This work extends what is achievable with the current microwave definition of the second, with the further development of two caesium fountains and the construction of a rubidium fountain. Optical frequency standards might eventually lead to a new definition of the SI second, and a large research effort is devoted to this goal.
The aim is to develop measurement standards based on counting elementary particles, with a priority being a quantum standard for electrical current. Other projects aim at developing a sound metrological basis for nanomagnetism, nanomechanical resonators and Terahertz photon counting.
An accurate measurement of the Boltzmann constant is being made, which will lead to a redefinition of the kelvin. Work is also underway on methods to disseminate a temperature scale above 1200 K through radiometry and eutectics.
Quantum properties can be exploited in computing, communications and measurement science to perform functions which are not possible with technologies based on macroscopic devices ruled by the laws of classical physics. Current work includes the development of standards for single photon detection and ion-trap entanglement.
