GPS can be jammed with a cheap transmitter, and increasingly is. Quantum sensors are being tested as a backup that navigates using the Earth's magnetic and gravitational fingerprints, signals no satellite jammer can switch off.
A commercial jet is cruising over eastern Europe when its navigation displays begin to lie. The GPS signal, a whisper from satellites 20,000 kilometres up, has been drowned out by a jammer on the ground that costs less than a laptop. For a few tense minutes the crew is flying on dead reckoning and nerves. Now picture the same cockpit, the same jamming, and a backup that, in company-reported trials, can still fix the aircraft's position to within a few metres. It is not listening to space at all. It is reading the Earth.
That is the promise of quantum navigation, and in 2025 and 2026 it moved from physics demonstration to something being flown, sailed and driven in real trials. The idea is old and the stakes are suddenly urgent, because the system it is designed to back up has turned out to be dangerously easy to switch off.
What actually happened
Jamming went from rare to routine, and a jam-proof backup went from theory to field trial.
Interference with satellite navigation, once mostly a wartime nuisance, is now a daily fact of aviation near conflict zones, with well over a thousand flights a day reporting problems. The standard fallback, an inertial system that tracks motion with gyroscopes and accelerometers, drifts, piling up errors of kilometres an hour with nothing to correct them. Into that gap has come a wave of quantum-sensor trials, led most visibly by the Australian company Q-CTRL.
In airborne tests, Q-CTRL reported its system fixing an aircraft's position tens of times more accurately than a high-grade inertial unit, with the best results down to a few metres, and it ran a gravity-based version continuously for days aboard a Royal Australian Navy vessel. Those headline multiples are the company's own figures, and they matter less than who is now paying attention. The global benchmarks are stacking up: the United States defence research agency DARPA put 24.4 million dollars into ruggedising quantum sensors with Lockheed Martin, Boeing has flown for hours on a quantum inertial unit, the national laboratory Sandia is shrinking the sensors onto chips, and the technology has passed the aviation industry's DO-160 environmental standard and met a formal navigation-precision benchmark used for instrument approaches.
There is a hard strategic edge to all this. A recent assessment from a United States national laboratory argued that quantum sensing, unlike quantum computing, is already delivering results in the field, and warned bluntly that America should reach independence from GPS before its rivals do, with China investing heavily in the same technology. That is why the money and the map-making are moving now. Resilient positioning has become a race rather than a research topic, and whoever holds the best magnetic maps and the smallest, most rugged sensors gains an advantage that depends on nobody's satellites. The same trials that impress an airline safety board are, quietly, a defence programme.
Every point on Earth has a slightly different magnetic and gravitational signature, set by the rock and iron beneath it. That pattern is fixed, published in the form of survey maps, and impossible to jam, because it is the planet. A quantum magnetometer uses the exquisite sensitivity of atoms or light to measure the local magnetic field far more precisely than older instruments could. Match that live reading against a stored map, the way a hiker matches the hills around them to the contours on paper, and you get a position with no signal from space.
You cannot jam the Earth's magnetic field. It has been broadcasting the same map for millions of years.
The reason this is a 2026 story and not a 1966 one is the second ingredient: artificial intelligence. A moving aircraft or ship is a storm of magnetic noise from its own engines and electronics, often far stronger than the faint signal from the ground below. Machine-learning software is what finally pulls the planet's whisper out of that racket, cleanly enough to steer by.
Why this matters
GPS is a single point of failure. Aviation, shipping, logistics, emergency services, even the timing signals that stamp financial trades all lean on it. A passive backup that cannot be jammed is now a national-security and civil-aviation priority, not a novelty.
The landmark scales. Because the reference is the planet itself, the same principle stretches from a fighter jet to a cargo ship to, one day, a self-driving car in a tunnel where GPS never reached.
Quantum sensing is the near-term payoff. While the world waits for quantum computers, quantum sensors are the branch of the field that already works, and navigation is its first big commercial use.
The honest catch
The best numbers are the vendor's. The tens-to-over-a-hundred-times accuracy claims come from company trials and preprints, not independent, peer-reviewed head-to-heads. Treat them as promising, not proven.
Unjammable is not infallible. The method is only as good as its maps, which are coarse in places and weak over the open ocean, and a geomagnetic storm or a vehicle's own interference can swamp the signal.
It is still rack-sized. Today's units are roughly the size of a small server rack. Genuinely small, cheap sensors for cars and drones are coming, not here, and the safety certifications prove ruggedness, not the accuracy claims.
EDITOR'S TAKE
GPS turned out to be a quiet miracle we forgot was fragile: a signal from 20,000 kilometres up, faint enough to drown out with a gadget that costs less than a phone. Quantum navigation is the unglamorous fix, not a replacement but a passive backup that reads a map nobody can switch off. The honest read is that the physics works and the trials are real, while the eye-catching accuracy multiples are still the vendor's own and the boxes are still rack-sized. But notice who is moving: a defence research agency, an aircraft maker, a national laboratory warning about falling behind. When militaries and airline safety boards start funding the same thing for opposite reasons, it has stopped being a demo. Watch two numbers: how small the sensor gets, and who publishes the first independent head-to-head.
Quick questions
Will this replace GPS?
Not replace, complement. Quantum navigation is designed as a backup that keeps working when satellite signals are jammed, spoofed or simply unavailable, such as underwater or deep indoors. The likely future is layered: GPS when you can trust it, a quantum-and-inertial system when you cannot.
How can a device know where it is with no signal?
It reads a signal that is always there: the Earth's own magnetic and gravitational field, which varies from place to place in a fixed, mapped pattern. A highly sensitive quantum sensor measures the local field and matches it to a stored map, the way a sailor once navigated by landmarks, except the landmarks are invisible and cannot be jammed.
Sources
Q-CTRL (Ironstone Opal): the quantum navigation system and its field-trial figures (company-reported).
arXiv: the technical preprint behind the airborne magnetic-navigation results (2025).
Lawrence Livermore National Laboratory: a strategic assessment of quantum sensing for GPS-denied navigation (2025).
GPS World: the DARPA quantum-navigation award with Lockheed Martin (2025).
Related from Frontier Signal: our recent deep dive on why fusion's hard part is now engineering, not physics. Frontier Signal explains frontier technology in plain English. Company-reported performance figures should be independently verified. This is general information, not investment advice.
