In our previous article, we looked at why Position, Navigation and Timing - or PNT - is becoming more vulnerable. Many systems we rely on every day use signals from satellites, but those signals can be disrupted by jamming, spoofing or signal loss.
Quantum technology offers a different way forward. Instead of depending only on external signals, quantum systems can measure the physical world around them — or measure movement directly. That makes them especially valuable in places where satellite signals are weak, blocked or deliberately denied.
Two of the most promising areas are quantum map matching and quantum inertial navigation systems.
Quantum map matching: using the world as a reference point
Gravity and magnetism are not exactly the same everywhere. They vary subtly depending on location, geology, buildings, infrastructure and other features in the environment. If these variations can be mapped accurately, they can be used like a physical fingerprint of a place.
A navigation system can then compare live measurements with this stored map to help work out where it is. This is known as map matching.
Quantum sensors such as gravimeters and magnetometers are important because they can detect very small changes in gravity or magnetic fields. They also need to have very low drift, so their readings stay accurate over time.
This is particularly useful in challenging environments. For example, underground trains cannot rely on satellite signals in the same way as systems above ground. QinetiQ, working with partners including Transport for London, PA Consulting, Imperial College London and the University of Sussex, has demonstrated the use of quantum magnetometers on London Underground trains to help track train position.
Because these systems do not depend on satellite signals, they are more resistant to jamming and interference. Over time, quantum map matching could help reduce reliance on GNSS and provide a more robust fallback when signals are unavailable or unreliable.
Quantum inertial navigation: reducing drift over time
Inertial Navigation Systems, or INS, are already used in situations where GNSS cannot be received - for example, in submarines. These systems start from a known position and then measure movement to estimate where an object has travelled.
The challenge is drift. Small errors build up over time, so the longer a system runs, the less accurate its final position can become. For example, a submarine may be able to accurately track its location for an hour, but after a day or a month, small measurement errors accumulate, resulting in a final location that could be miles off course.
Quantum inertial sensors could help solve this problem. They are expected to offer much lower drift than conventional sensors, which means navigation systems could stay accurate for longer without needing an external signal to correct them.
QinetiQ is working with partners developing sensors in this field, with a particular focus on how these sensors and the data they produce can be integrated into wider navigation systems. In partnership with Infleqtion, QinetiQ has successfully operated a quantum clock and a quantum inertial sensor (both key components of a functional quantum navigation system) aboard a test flight, highlighting the potential of this technology.
What comes next
Quantum navigation is still developing and is not yet ready for widespread everyday use. But as the technology matures, it could play an important role in making navigation more resilient, especially in complex, contested or signal-denied environments.
This concludes Part 2 of our exploration of PNT. In Part 3, we will look at how combining multiple technologies and using data fusion could enable the next generation of resilient and dependable navigation.
