In early 2025, a Chinese naval task group conducted a full circumnavigation of Australia. Ships were tracked, movements observed and conclusions quickly drawn.
Much of the commentary treated it as a show of force – an assertion of reach in the Indo-Pacific. But what if China’s real objective was less political, less about capability signalling and more about gathering data to map the environment it may one day have to navigate?
Australia has been pursuing exactly that – and has lately made significant technical progress in the area.
In July 2025, Sydney-based quantum tech firm Q-CTRL conducted the world’s first trial of its advanced quantum navigation sensors aboard the government vessel ADV Sycamore, in partnership with the Australian Department of Defence. Central to the technology was a quantum dual gravimeter installed in a standard server rack in the ship’s communications room, bolted directly to the deck with no special vibration isolation.
The breakthrough was not just the sensors’ sensitivity but the software that made fragile quantum hardware viable at sea. Developed and fielded in just 14 months, the sensors marked a clear step from laboratory promise to operational capability.
At the heart of this shift are gravimeters – instruments that measure tiny variations in the Earth’s gravitational pull. Those variations exist because the seafloor is not uniform. A deep trench pulls differently than a ridge. Dense rock pulls differently than soft sediment. Every patch of ocean bottom has its own gravitational signature.
Unlike aircraft or surface vessels, submarines cannot use GPS: the signal does not penetrate seawater. They rely instead on inertial navigation, which accumulates error over time. Previously, correcting that drift meant surfacing or raising an antenna to gather a signal – exposing the vessel to detection, jamming or interception. Quantum gravimetry offers a way to recalibrate while remaining fully submerged, using only the environment itself.
But to do this requires a map.
If you sail across an area recording gravity readings, you build a reference library of what the gravity looks like at every point. Put a gravimeter on a submarine and it can take a live reading, compare it against that map, and fix its position precisely. No transmission is required. There’s nothing to detect.
The Q-CTRL trial aboard Sycamore ran continuously for more than 144 hours in real maritime conditions, collecting usable data without human intervention. It worked.
Quantum sensing of this kind reframes how we assess power at sea. We tend to measure strength through visible equipment and their characteristics – submarines, missiles, range and stealth. These remain essential.
But in oceans increasingly populated by manned and unmanned systems, precise positional awareness becomes an advantage that compounds across every element of naval warfare – the accuracy of munitions, the effectiveness of surveillance, the coordination of dispersed assets. Knowing exactly where you are, and where everything else is, is increasingly the decisive edge.
Australia brings distinctive strengths to this domain. Decades of research in quantum sensing and precision measurement across the Defence Science and Technology Group, the Australian National University, Adelaide University, Swinburne University of Technology and the University of Sydney have laid the groundwork. Recent progress has accelerated the critical transition from laboratory instruments to systems that can survive harsh, noisy conditions, and therefore be used operationally. Q-CTRL’s software-driven approach to suppressing vibration and environmental interference has been central to that shift.
Decades of operating sensors in some of the world’s most demanding mining environments have given Australia a head start others lack. Gravimeters are already widely used in mineral exploration, and Australia’s mining sector has been an early and demanding adopter – driving the development of sensors rugged enough to operate in remote, hostile field conditions. Australian companies including Q-CTRL and Nomad Atomics are now translating that field experience directly into quantum sensors for defence applications.
A broader pattern is emerging. Australia is specialising in high-value technologies, ranging from advanced manufacturing for strategic technology platforms to quantum sensing that enables reliable navigation for submarines and uncrewed systems. These are the quiet enablers that determine whether headline equipment can operate effectively when space-based systems are degraded or denied.
China’s systematic surveying and mapping efforts, including activity around Australia, are better understood through this lens. The accumulation of detailed gravity data suggests a long-term investment not just in presence but also in environmental dominance for navigation, detection and concealment.
Much of this is in the early stages. Quantum gravimeters face hurdles in miniaturisation, sensor fusion and the creation of sufficiently detailed operational maps. Scaling from successful trials to fleet-wide capability will require sustained investment and close trilateral cooperation. The United States and Britain bring critical strengths at scale.
Australia’s position is not marginal. By combining research depth, software-driven ruggedisation and resource advantage, it is building leverage in a domain that will be central to future conflict in the Indo-Pacific.
Submarines will continue to dominate headlines as symbols of deterrence. But their effectiveness, and that of the force around them, will increasingly depend on something less visible: the quality of the map they move through, and their ability to update it.
Undersea warfare may be decided less by what moves through the ocean, and more by how well the ocean is measured.
Article reprinted with permission from the Australian Strategic Policy Institute's analysis and commentary site The Strategist.
