For the first time an unmanned underwater drone navigated relying not on external satellite signals but on an internal atomic clock, capable of keeping time with a precision comparable to that of the best metrology laboratories. The experimentation involves the Royal Navy, the British company MSubs and Infleqtion, a company working on quantum technologies based on neutral atoms. The system tested is a compact optical atomic clock called Tiqker, designed to be used on the operational vehicle and to provide extremely stable timing, useful in all those situations in which GPS is not available or compromised. Since submarines, especially those that must maintain stealth, cannot rely on signals from satellites for long, having an independent and ultra-accurate time reference on board for the exact time improves navigation, the security of on-board systems and coordination with other units.
The experiment took place on the Excalibur (XCal) extra-large autonomous underwater vehicle, the Royal Navy’s experimental platform. The success of the trial was described by Matthew Steele, Futures manager at the Royal Navy’s Disruptive Capabilities and Technologies Office, as a «first critical step towards understanding how quantum clocks can be used on underwater platforms to enable precision navigation and timing (PNT) to support sustained operations».
How the Tiqker atomic clock works
The trial, considered a “first operational deployment” of this type of technology, saw Tiqker installed directly on XCal, a submarine which serves as a test bed for the Royal Navy as part of the development of extra-large autonomous underwater vehicles. Optical atomic clocks like Tiqker base their operation on the behavior of neutral atoms cooled and manipulated by lasers, so as to generate an extremely stable frequency. This precision is fundamental in all those contexts in which the position is calculated by exploiting the integration of speed and direction over time. If the temporal “beat” alters, even very slightly, the navigation error grows to the point of making the estimated position imprecise.
In conventional submarines, or even in other vessels that operate without constant contact with satellites, onboard instruments rely on microwave clocks, which while accurate tend to show some drift over time. This drift, i.e. the accumulation of small errors, becomes particularly critical when it is not possible to receive updates from the satellite positioning system or GNSS (Global Navigation Satellite System). In an underwater environment, where emerging can mean revealing one’s presence, a totally autonomous time reference that is highly resistant to disturbances represents a significant operational advantage. Tiqker provides just that: a constant signal that allows other on-board instruments – such as sonars, motion control systems, encrypted communications equipment or ballistic computers – to rely on a stable measurement of time. In other words, the accuracy of the atomic clock directly reflects on its ability to understand location, plan safe routes, and coordinate by other means without making itself traceable.
Not a finish line, but a great starting point
Even if the test should not be interpreted as a goal achieved, but as an excellent starting point, what happened in the tests is worthy of note. This is why Matthew Troughton, technical director of MSubs, expressed some enthusiasm with these words:
The integration of a quantum clock on XCal demonstrates how advanced synchronization can redefine the capabilities of autonomous submarines. This testing paves the way for platforms capable of operating independently for longer periods, with the precision and reliability needed for future undersea missions.
Ryan Hanley, UK general manager of Infleqtion, expressed satisfaction with the success of the operation and declared:
By installing Tiqker directly on the Royal Navy’s Excalibur (XCal) submarine, a next-generation autonomous platform, we are laying the foundations for fleets to navigate, coordinate and operate with precision in any environment.
