The US Defence Advanced Research Projects Agency (DARPA) has announced a programme to create optical atomic clocks to improve time synchronisation.

The Robust Optical Clock Network (ROCkN) scheme aims to develop clocks with low size, weight and power that can offer better timing accuracy and holdover than global positioning system (GPS) based atomic clocks.

DARPA said that time synchronisation is ‘critical’ to achieving mission success in modern warfare.

DARPA Defence Sciences Office programme manager Tatjana Curcic said: “The goal is to transition optical atomic clocks from elaborate laboratory configurations to small and robust versions that can operate outside the lab.

“If we’re successful, these optical clocks would provide a 100-fold increase in precision, or decrease in timing error, over existing microwave atomic clocks, and demonstrate improved holdover of nanosecond timing precision from a few hours to a month.

“This programme could create many of the critical technologies, components and demonstrations leading to a potential future networked clock architecture.”

The programme will consist of two separate phases. The first phase will involve developing a robust, high-precision small portable optical clock that can fit on a fighter jet or satellite.

This clock should be capable of providing picosecond (one-trillionth of a second) accuracy for 100 seconds and must be able to withstand temperature, acceleration and vibrational noises.

The programme’s second phase will aim to build a larger clock with ‘unprecedented’ holdover performance. The clock should fit in a navy ship or a field tent and should provide GPS-equivalent, nanosecond precision for 30 days in the absence of a GPS system.

The ROCkN scheme is due to last for four years, with each phase taking two years.

At the end of the programme, participants will need to demonstrate synchronisation between stationary, mobile and airborne clocks with enough timing precision for 100GHz distributed coherence.