Q-CTRL Navigates Ship Without GPS Using Quantum Gravity
During trials in the Coral Sea off eastern Australia, Q-CTRL successfully navigated a maritime vessel without GPS. The company achieved this by using a quantum gravimeter to detect subtle variations in Earth’s gravity, and reported a positioning accuracy within one nautical mile. Q-CTRL has also published a technical manuscript detailing its methods. This demonstration represents a field test of a sensor correcting an inertial system, not a deployed product on operational ships.
Q-CTRL’s breakthrough
According to the August 27 press release, the system, named Ironstone Opal, determines position by matching real-time gravity readings with existing gravity maps. This position estimate then corrects an inertial navigation system. Q-CTRL states that the sensor operated autonomously within a passenger cabin, without requiring temperature control, gyroscopic stabilization, or frequent recalibration. This last point is a key differentiator, as previous public demonstrations of gravity-aided navigation often relied on GPS signals, regular recalibration, or specialized installation.
Q-CTRL describes this achievement as a “world-first” and identifies itself as “the global leader in quantum infrastructure software.” Both are self-attestations. The one-nautical-mile accuracy figure, a headline metric, comes from Q-CTRL’s internal trials and has not been independently verified. The full results are detailed in a manuscript titled “GNSS-free quantum gravity-aided navigation and fine-scale marine surveying with a strapdown quantum gravimeter,” though its peer review status is not specified.
This maritime application builds upon Ironstone Opal’s magnetic navigation (MagNav) capabilities, which Q-CTRL previously demonstrated in ground and airborne trials in April 2025. Gravity maps are more readily available at sea, a factor in the company’s decision to develop this maritime variant.
Context and unaddressed information
Q-CTRL frames this demonstration in the context of electronic warfare, citing approximately 978,000 GPS jamming events globally in the first quarter of 2026. Of these, 98% concentrated in the Middle East, affecting over 1,100 vessels. The source of these figures is not provided in the release. The company also lists defense clients, including DARPA, the U.S. Defense Innovation Unit, the Australian Department of Defence, the UK Royal Navy, and other AUKUS partners.
Jason Ralph, Professor of Electrical Engineering and Electronics at the University of Liverpool, offered a realistic perspective on alternative navigation technologies:
“Whilst there are a number of ‘Alt-Nav’ technologies that can help to provide resilience, they all have limitations and their own vulnerabilities. Gravity sensing and map matching is the only passive Alt-Nav technology that is global in extent and is impossible to jam or to spoof.”
The release doesn’t specify the number of trial runs, the range of sea conditions tested, the sensor’s size and power consumption, or whether any third party verified the accuracy claim. A one-nautical-mile correction to an inertial system’s value depends on the drift over the mission length, which the summary doesn’t quantify. Until the manuscript undergoes review, the presented metrics should be considered Q-CTRL’s own.