Introduction
For more than three decades, GPS has been the invisible backbone of modern navigation. From smartphones and aircraft to military systems and precision weapons, billions of devices depend on signals transmitted from satellites thousands of kilometres above Earth. However, GPS has a fundamental weakness: the signal reaching Earth is extremely weak and can be disrupted through jamming, spoofing or denial.
This vulnerability has pushed defence agencies to explore a new generation of navigation systems that can operate without external signals.
One promising solution is quantum navigation, where sensors use the fundamental behaviour of atoms and quantum materials to measure motion, gravity and magnetic fields with extraordinary precision.
The Concept: Navigating Through Physics Instead of Satellites
Traditional GPS determines position by measuring the time taken for signals from multiple satellites to reach a receiver. Quantum navigation takes a completely different approach: it measures the movement of the vehicle itself.
A key technology is the quantum inertial navigation system (QINS), which uses atom interferometry. In these systems, ultra-cold atoms such as rubidium or cesium are cooled using lasers until they behave like precise quantum waves. When the sensor moves, the atoms’ quantum interference pattern changes. By measuring this change, the system can calculate acceleration and rotation without needing GPS signals.
Another approach uses quantum magnetometers, including sensors based on nitrogen-vacancy (NV) centres in diamond. These sensors detect tiny variations in Earth’s magnetic field created by geological structures. Since these magnetic patterns are naturally occurring and extremely difficult to replicate, they can act like a fingerprint for location. Systems such as AQNav combine quantum magnetometry with artificial intelligence to match magnetic measurements with geological maps, enabling GPS-independent navigation.
Why Quantum Sensors Are So Sensitive
The advantage comes from using quantum states as measurement references.
Atoms and electrons have properties such as spin and energy states that respond predictably to external forces. A small acceleration, rotation or magnetic field creates measurable changes in these quantum states. Unlike conventional sensors, which are limited by mechanical imperfections and electronic noise, quantum sensors use stable atomic properties as the reference point.
This is similar to how atomic clocks keep time by measuring transitions between atomic energy levels. In quantum navigation, the same principle is applied to movement and position.
Materials Behind Quantum Navigation
Different quantum sensors rely on different materials:
- Rubidium and cesium atoms: Used in cold-atom interferometers and atomic magnetometers because their quantum transitions are highly stable.
- Diamond with nitrogen-vacancy (NV) centres: A carbon crystal containing engineered atomic defects that act as sensitive quantum probes.
- Superconducting materials: Used in SQUID-based sensors for detecting extremely weak magnetic fields, although they require cryogenic temperatures.
- Silicon-based photonic platforms: Being explored to make quantum sensors smaller and more practical for field deployment.
The Trade-Off: Precision vs Practicality
Quantum sensors promise exceptional sensitivity, but replacing GPS completely is not straightforward.
The biggest challenge is miniaturisation and ruggedisation. Laboratory quantum sensors often require vacuum chambers, lasers, temperature control and vibration isolation. Turning these systems into compact devices that can survive aircraft, ships or battlefield conditions remains a major engineering challenge.
Cold-atom systems also consume more power and are currently more complex than conventional inertial sensors. Meanwhile, NV-diamond sensors are more robust but generally do not yet match the ultimate sensitivity of laboratory-scale atomic systems.
Therefore, the near-term future is unlikely to be a complete replacement of GPS. Instead, quantum sensors will work alongside existing technologies, providing navigation resilience when satellite signals are unavailable or unreliable.
The Future of Navigation
The race for GPS-independent navigation reflects a broader shift: future systems will rely less on external infrastructure and more on sensing the physical world itself.
Quantum sensors could allow submarines to navigate underwater, aircraft to operate in GPS-denied environments and autonomous vehicles to maintain position where satellite signals fail. Recent demonstrations of quantum gravity-aided navigation show the potential of using Earth’s natural gravitational variations as a reference for navigation without GNSS signals.
The goal is not simply to build a better GPS. It is to create navigation systems that remain reliable even when GPS is unavailable—a capability that could redefine military, scientific and commercial mobility.
References for Further Reading
- NIST — Quantum Sensing and Atomic Magnetometry
https://www.nist.gov/quantum-information-science - Barry et al., Sensitivity Optimization for NV-Diamond Magnetometry, Reviews of Modern Physics
https://doi.org/10.1103/RevModPhys.92.015004 - SandboxAQ — AQNav: Quantum Magnetic Navigation
https://www.sandboxaq.com - Everitt et al., GNSS-free quantum gravity-aided navigation and fine-scale marine surveying with a strapdown quantum gravimeter (2026)
https://arxiv.org/abs/2608.25563 - Kitching, Chip-scale atomic devices, Applied Physics Reviews
https://doi.org/10.1063/1.4977562
Lateral Thinking 
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