Reporting and photography by Mike Cherney

GRIFFITH, Australia -- At a tiny airport in the Australian countryside last month, a small plane took off carrying a device that could transform how U.S. drones, aircraft and ships navigate across future battlefields.

The flight carried an instrument that shines lasers at atoms, which behave like compass needles to measure Earth's magnetic field in real time. Readings from the device can be compared to a magnetic-field map, helping a user determine their location -- and offering a backup to satellite-based navigation like GPS.

For the U.S. and its allies, finding new ways to navigate is crucial. In the Ukraine war, Russia is jamming and spoofing -- blocking and faking signals -- so frequently that satellite navigation isn't dependable. Other potential adversaries, including China and North Korea, possess similar capabilities.

GPS spoofing by militaries has become a civilian hazard as well, presenting a risk to commercial aircraft.

"This problem hasn't been as urgent until right now, when we are seeing the end of reliable GPS," said Russell Anderson, a principal scientist at Q-CTRL, the Australian startup that ran the test flight. "It is the arms race of the current day, in terms of navigation."

Scientists around the world are exploring whether harnessing the quantum properties of atoms can help navigate accurately in so-called contested environments. But it is still unclear whether the devices, which work well in labs and field tests, would perform reliably on actual military missions.

The Pentagon is hoping to solve that problem. In August, the research and development agency at the Defense Department launched a program to help make quantum sensors more robust.

The agency said the extraordinary sensitivity of the devices makes them fragile in real-world environments, where vibrations or electromagnetic interference can degrade performance. Australia-based Q-CTRL was selected to participate; another company, Safran Federal Systems in Rochester, N.Y., also said it was awarded a contract.

The work is taking on increasing urgency. Russia and China have advanced their electronic-warfare capabilities. European officials have accused Russia of widespread jamming of aircraft.

The problem with GPS is the signals are typically weak, making them easy to block. The U.S. has been rolling out a new, more powerful GPS signal for the military called M-code that is more resilient to jamming, but there has been a holdup in getting funding for the receivers needed to use it, said Todd Harrison, a senior fellow at the American Enterprise Institute who focuses on defense strategy and space policy.

"The U.S. military now realizes future battlefields will be fully contested in the electromagnetic domain unlike anything we have seen before," he said.

Quantum devices, potentially working together, could tip the balance, proponents say. Quantum clocks, for example, could boost the precision and accuracy of timekeeping. Another quantum sensor, also being developed by Q-CTRL, can navigate by detecting small changes in gravity.

"Quantum sensing is a priority," said Tanya Monro, the chief scientist for Australia's Department of Defence, which hosted a trial of the Q-CTRL gravity sensor on one of its ships. "There is an absolute, driving need to be able to operate with complete denial of GPS."

The Q-CTRL device on the plane in Griffith, a city of about 27,000, is called an optically pumped magnetometer. It shoots lasers at atoms of rubidium, a soft, silvery-white metal, that are held in a gaseous form in a small glass vial. The lasers help measure changes in the atoms' internal compass needle, which is used to calculate the strength of the magnetic field.

Q-CTRL's software then removes interference from outside sources, such as the aircraft itself, producing an accurate measurement of the Earth's magnetic field in that location, which can be compared to a magnetic map. Such maps show deviations from the average field strength over the surface of the Earth.

"You can go out in the woods, and with a map and your eyes identify, 'Well, there's a hill and there's a valley and there's a stream, so I think I'm right here on the map,'" said Michael J. Biercuk, the American quantum physicist who founded Q-CTRL. "You can do exactly the same thing with these magnetic signals."

Biercuk said there is no realistic way to jam quantum magnetometers or gravimeters from a distance, short of an energy pulse that would fry all the electronics on a plane and cause it to crash. He said Q-CTRL has subjected the sensors to shaking and dynamic maneuvers with good results -- including more than 140 hours of continuous operation on the Australian ship.

In Griffith, Q-CTRL engineers tested three magnetometers in different locations on the airplane, given that the external interference in each spot is different.

The units were tested against a high-end inertial navigation system -- which estimates position by using gyroscopes and accelerometers. These systems are already used as GPS backups and on submarines, which can't access GPS when underwater. But inaccuracies build up over long distances.

All three locations performed comparably, Biercuk said. Over an 80-mile test window, a sensor on the tip of the plane's wing resulted in an average position estimate within about 620 feet of the true position, and the margin of error didn't increase with the duration of the flight, he said. The performance was more than 10 times better than the inertial navigation system.

GPS is still very precise, when it's available. GPS-enabled smartphones are typically accurate to within 16 feet under open sky, according to one study.

There are challenges with the magnetometer approach. One is the need to have detailed magnetic maps, which may not always be available or up-to-date. Another is to make the device inexpensive enough for cheap drones like those that have transformed military strategy in Ukraine.

"Quantum offers a lot of potential," said Allison Kealy, a professor at Swinburne University of Technology in Melbourne, Australia, who specializes in positioning and navigation. She noted, though, that "I think they're like any other sensor. They have their strengths and weaknesses."

Others are exploring different techniques. Advanced Navigation, a company in Australia that makes inertial navigation systems, is preparing to launch a sensor that measures an aircraft's velocity in three dimensions by shooting lasers at the ground. That works in tandem with inertial navigation systems to improve accuracy over longer distances.

"No one solution fits all problems," said Max Doemling, chief product officer at Advanced Navigation, which has collaborated with Q-CTRL in the past. Doemling said his company would be interested in using quantum sensors when the technology is ready.

In Griffith, not everything went smoothly at Q-CTRL's flight tests. At one point, there was a communication issue involving the wingtip sensor, and it was swapped out for a different unit.

More work is ahead, some of the Q-CTRL scientists said, to show the sensors can handle different scenarios that a military platform might face.

"Can it survive a rocket launch? Can it survive a crash landing?" said Yuval Cohen, a Q-CTRL researcher. "You don't really know, until you do the testing."

Write to Mike Cherney at mike.cherney@wsj.com

(END) Dow Jones Newswires

November 19, 2025 22:00 ET (03:00 GMT)

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