Satellite navigation was once the quiet, invisible backbone of modern warfare. For decades, GPS gave the US military a decisive edge: precision strikes, coordinated operations and near-flawless navigation across land, sea and air. But the world has changed. On modern battlefields from Ukraine to the South China Sea, GPS has become unreliable and dangerously easy to disrupt. A technology designed for clean skies and uncontested airspace is now struggling in an era of electronic warfare.That vulnerability has pushed the Pentagon towards an unlikely alternative built not in space, but in physics labs. The question shaping defence strategy today is simple: if satellites go dark, can quantum sensors guide the military instead?
What’s going wrong with GPS?
The issue is not precision. When it works, GPS can pinpoint a location within a few metres. The problem is survivability.
- Modern electronic-warfare units can interfere with GPS signals in two ways:
- Jamming: Floods the receiver with noise so the satellite signal cannot be heard.
- Spoofing: Sends a fake signal that tricks an aircraft, drone or missile into believing it is somewhere else.
Both attacks are cheap, effective and increasingly common. The conflict in Ukraine has shown how heavily and routinely Russia deploys these techniques. Civilian aircraft, drones and communications systems have been caught in the crossfire.For the Pentagon, this is a strategic nightmare. The assumption that GPS would always be available no longer holds. Defence analysts now warn that future battlefields will be fully contested in the electromagnetic spectrum. If satellites are jammed or blinded, the US military needs a fallback.
What is the quantum alternative?
One of the most promising options is a new class of navigation tools built on quantum physics.At a small airport in Griffith, Australia, researchers recently tested an optically pumped magnetometer, a sensor that determines position using Earth’s magnetic field instead of satellites.Here’s how it works:
- The device contains atoms (often rubidium) that behave like tiny compass needles.
- When struck by precisely tuned lasers, the atoms’ internal states shift depending on changes in Earth’s magnetic field.
- By comparing these shifts to a pre-mapped magnetic signature of the region, the system can calculate where it is in real time.
- In simple terms, it reads the magnetic landscape the way GPS reads satellite timing signals.
This technology is part of a broader push into quantum navigation, which also includes quantum clocks and gravity sensors.
Does it actually work?
Early tests suggest the answer is yes — with caveats.
- In the recent Australian flight trial:
- Three magnetometers were mounted on a small aircraft.
- Their readings were compared against a modern inertial navigation system (INS), the standard non-satellite backup used today.
- The quantum sensors performed better over long distances.
- On one wingtip unit, average positional error during an 80-mile test was roughly 620 feet.
Crucially, the error did not drift significantly over time. INS systems accumulate drift, which compounds over long missions.The same sensor has also operated continuously for more than 140 hours during naval trials, withstanding vibration and movement without losing accuracy.Researchers say the system cannot realistically be jammed. To interfere with it, an adversary would have to physically damage the aircraft or deliver an energy pulse strong enough to kill all electronics on board.So why isn’t the Pentagon rolling this out yet?Quantum sensors are powerful precisely because they are sensitive. That sensitivity is also what makes them difficult to operate in the chaotic conditions of war.Key challenges include:1. Magnetic mapsThese sensors need extremely detailed magnetic-field maps. Building and updating such maps over potential conflict zones is a slow, complicated process.2. Sensitivity to noiseQuantum devices can be disrupted by vibration, rapid manoeuvres and stray electromagnetic fields — all common in military environments.3. CostTo be useful for mass deployment on drones, vehicles and munitions, sensors must be cheap and rugged. Today’s prototypes are not.4. Industrial readinessField tests still produce occasional glitches. One sensor in the Australian trial had to be replaced due to communication issues. For frontline use, the technology must withstand shock, temperature extremes and high-G launches.
Are there non-quantum alternatives?
Yes. Several defence companies are exploring:
- Laser-based velocity sensors
- These use fast-moving laser pulses to measure how quickly an aircraft is travelling relative to the ground. Combined with inertial navigation, they reduce positional drift over long periods without external signals.
- Hybrid navigation
Most defence researchers agree no single technology will replace GPS entirely. The future will likely combine:
- Inertial navigation
- Quantum magnetometers
- Quantum clocks
- Optical systems
- Terrain or magnetic-map matching
- Each covers a gap left by another.
Why this matters
Electronic warfare is becoming the defining feature of modern conflict. If GPS can be denied quickly and cheaply, reliance on satellites becomes a critical vulnerability.Navigation underpins everything — drones, submarines, missiles, logistics, troop movement, airpower. A single point of failure affects an entire military ecosystem.Quantum navigation, even if imperfect today, offers the first realistic path to satellite-free precision. It promises autonomy in environments where GPS is degraded or destroyed, and reduces dependence on space-based infrastructure that adversaries can target.The Pentagon’s growing urgency reflects a broader truth about global security: the era of effortless GPS dominance is ending. The next war will require navigation systems that can survive without satellites — and quantum physics may hold part of the answer.
