We need to talk about time

How quantum technologies will protect critical infrastructure

We think of time as constant, reliable. Always working in the background, like a beating heart. Our watches will keep ticking. With a click or a tap, our phones and laptops will show the correct time. But, like a heart, time keeping is not infallible.

Time is a resource, and an essential one at that. Almost everything relies on time to function properly: financial markets, data communication, energy grids, navigation, transport. But despite being a critical utility, timing is vulnerable to disruption and outages due to how the world’s high-tech atomic clocks work with Global Navigation Satellite Systems (GNSS). These are constellations of satellites that use highly precise atomic clocks that provide position, navigation and timing services around the world.

"More reliable timing means greater energy efficiency, better autonomous navigation, and faster data communication."

GNSS has been revolutionary. But the problem is it relies on radio signals, which are easily interfered with, and signal coverage significantly reduces at the Earth’s poles and completely vanishes in some environments, under water for example.

While the navigation chaos caused by GNSS outages has been well documented, a less talked about area is the impact they have on the world’s time keepers. Even small errors in a satellite’s clock can lead to significant disruption.

It’s not just about mitigating the risks either. More reliable timing brings with it a whole host of benefits. It means greater energy efficiency, better autonomous navigation, and faster data communication, to name just a few.

Our mission is to make this a reality, and we are developing the hardware to do exactly that. What is needed at the same time is greater understanding of the very real vulnerabilities of GNSS and the very real alternatives to it and the benefits they bring. An article in the Financial Times that made the rounds in our office, all about the fight to protect our time keepers and the people championing it, shows how this is progressing.

But the clock is ticking. Our dependence on GNSS makes us vulnerable and the mission to find an alternative is urgently underway.

The coldest place in the universe

Cold atom technology is Aquark’s bread and butter. We build the smallest and most deployable cold atom quantum hardware in the world to enhance accuracy, precision, and stability for critical industries – like position, navigation and timing.

Governments around the world, including here in the UK, are backing cold atom technology as an alternative to GNSS. In 2023, with support from a £3.4 million Small Business Research Initiative (SBRI) grant from Innovate UK, we developed AQlock, the UK’s first industrially designed and built commercial cold atom-based atomic clock.

So how does AQlock work? And how is it an alternative to GNSS?

All high-precision timing systems measure the naturally stable resonance frequency of an atom and use this to correct a crystal oscillator. But, to generate the highest accuracy, you must access the atom undisturbed for as long as possible to remove noise and average out random variations.

The pale red dot: an atom which has been laser-cooled, suspended in a vacuum chamber

At Aquark, we do this by laser cooling the atoms close to absolute zero – a temperature of minus 273.149996°C, to be exact – which is what we have built with AQlock. Effectively, in our lab, we’ve made the coldest place in the universe(1).

At this extreme temperature, the atom’s natural quantum ‘tick’ can be measured for long periods. The frequency of the crystal oscillator is then checked against the atomic frequency and automatically corrected if needed, reducing its long-term drift without requiring any correction from the timing signal usually provided by GNSS.

In order to build something better, you have to break it first

But building the clock is half the battle. To be a commercially viable alternative to GNSS, it needs to be able to work outside the lab, in real-world, and often challenging, conditions.

Cold atom technology represents a fundamental shift towards resilient, independent infrastructure.

We are strong believers that actions speak louder than words, and so we set about proving this. We partnered with the Royal Navy and put AQlock to the ultimate test: deploying our cold atom clock aboard HMS Pursuer for a three-day sea trial. In a world-first, the AQlock operated continuously, providing precise timing even in rough sea conditions without a single correction from GNSS.

Operational outside the lab? Tick. What about when up against the current national standard for time-keeping?

For this, we took the AQlock to the National Physical Laboratory (NPL), the gold standard for measurement in the UK, to be independently tested against the internal Oven Controlled Crystal Oscillator (OCXO) – a device currently used today which ensures timing reliability using a temperature-controlled crystal oscillator. The results showed the AQlock capable of outperforming the OCXO in maintaining its accuracy and overcoming long-term drift, proving that our clock is indeed quantum enabled.

Results like this from the keepers of national timing standards, the UK’s Time Lords, if you will, shows how deploying high-performance timing solutions to secure the UK’s national infrastructure is not a far away possibility. It’s a short-term inevitability.

The Aquark team with AQlock (front left), our cold atom clock, on board HMS Pursuer

A secure future for time

As the FT article rightly states, the need for a more resilient timing infrastructure is here and now, and we believe that cold atom technology is the key to making it a reality.

As our world becomes increasingly interconnected and dependent on precise timing, the risks of GNSS disruption grow. But the solution is here. Cold atom technology represents a fundamental shift towards resilient, independent infrastructure.

Check out our work with NPL and Innovate UK to see how our mission to protect time is progressing.

(1) The cosmic microwave background of the universe is 2.725K meaning a grouping of atoms at a temperature below this has to be artificially achieved. Subject to the existence of other advanced alien civilisations, this makes these manmade states of matter the coldest in the Universe. It is worth recognising that researchers across the world have pushed the limits of science to even colder temperatures than we operate with at Aquark using more advanced techniques. These are amazing feats of human engineering, however to achieve these require even more advanced equipment which make them impractical for use outside of labs, for now at least.

But the clock is ticking. Our dependence on GNSS makes us vulnerable and the mission to find an alternative is urgently underway.