Time and frequency

The birthplace of atomic timekeeping and the home of UK time

We provide customers and partners with access to trusted and reliable time, and push the boundaries of timing technologies

NPL operates the national time scale UTC(NPL) and the UK primary frequency standards, and uses these to contribute to global timekeeping. We also disseminate accurate time and frequency to users across the UK, via services such as the MSF radio time signal, our internet time service, and NPLTime®. Atomic timekeeping underpins technologies that are part of our daily lives, such as mobile phones, the internet and global navigation satellite systems.

We carry out a broad programme of research in time and frequency metrology. We are developing and characterising a new generation of optical atomic clocks which are based on laser-cooled trapped ions and atoms. Although improvements to the stability and accuracy of these clocks are ongoing, they already surpass the performance of existing caesium primary standards. We participate in European collaborations to verify the international consistency of the new clocks. This work is expected to lead to a redefinition of the SI unit of time, the second. Optical atomic clocks have the potential to improve satellite navigation systems and measurements of the Earth's gravity potential, as well as test fundamental physical theories.

We are developing compact and user-friendly frequency standards for applications in navigation, high-speed communications, security and defence. We are also applying the techniques that underpin atomic clocks to develop new quantum sensors such as atomic magnetometers and inertial sensors.

Time and frequency is part of the wider quantum activities in NPL known as the Quantum Metrology Institute.

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Our research

From keeping the UK 'on time' to developing new technologies that could lead to a redefinition of the second, our researchers carry out a broad range of time and frequency measurement research.

Time scales

We maintain the national time scale and the primary standards for frequency, contribute to global timekeeping, and disseminate accurate time and frequency to users across the UK

Optical atomic clocks

We are developing the next generation of optical atomic clocks that promise to deliver even greater accuracy

Optical frequency comparison and dissemination

Our femtosecond combs and optical fibre links enable clocks to be compared with high accuracy, opening up exciting opportunities from fundamental physics tests to new technological applications

Compact atomic clocks

We are working to miniaturise accurate atomic clock technology to unlock new applications for precise timing


We study chip-integrated photonic systems for precision metrology, realisation of compact optical frequency combs, nonlinear photonics, and sensor technologies

Quantum sensors

Our quantum sensors enable precision measurements of gravity, inertial forces and magnetic fields, which are important for applications in geology, construction, navigation, security, metrology and fundamental science

Trace gas detection

Our expertise in frequency stabilised lasers for optical clocks enables developments in trace gas detection

Our services

We offer timing solutions and services to industries as diverse as communication, finance and energy, from delivery by radio signal and fibre, to equipment calibration.

We also provide reference standards and expert consultancy to industry, academia and government.

Case study

Delivering trusted time for UBS infrastructure


Our resources

We have a large number of freely-available publications by our team. Search our comprehensive list of resources.


Our team

Our people are leaders in their fields. Take a look at our time and frequency team.
View our team