Quantum Inertial Navigational Sensors Go Beyond the Prototype… but How Far Can They Commercialize?

The U.S. Space Force and Boeing recently announced they will be launching the X-37B spacecraft on its eighth mission in August 2025. Crucially, one of the technologies it tests is a high-performance quantum inertial sensor developed with the assistance of AOSense (United States), to deliver Global Navigation Satellite System (GNSS) jamming-resistant Positioning, Navigation, and Timing (PNT) data for spacecraft and ground control.

While the spacecraft is largely operating at 240 Kilometers (km) to 800 km, which is below the operational orbit of 20,200 km Global Positioning System (GPS) satellites, there is growing interest in valuable assets such as spacecraft, commercial and government satellites, aircraft, and even land-based vehicles, to have a backup or alternative PNT solution to GNSS. These “dead zones” are starting to proliferate, which could have a detrimental impact on a range of government, military, commercial, and consumer communications. Due to the Russo-Ukrainian War, it has been found that GNSS signals have been jammed or spoofed, up to 1,930 km into space. That will affect satellites in Low Earth Orbit (LEO) and even potentially Medium Earth Orbit (MEO). Other dead zones can be found at: the South Korean/North Korean border; the Eastern Mediterranean near Lebanon and Israel; the Suez Canal; and the Black Sea near Crimea and the Russian-Scandinavian frontier.

Given these challenges, it is not surprising that interest in quantum inertial sensors is building. What is a quantum-enabled Inertial Navigation System (INS), and could it replace GNSS?

One of the main approaches to developing quantum inertial sensors has been to harness superconducting, atom-based interferometry to detect acceleration and changes in orientation. Rubidium-87 atoms are put in a state of superposition by being cooled down to nanokelvin levels and then manipulated by lasers operating at 780 Nanometers (nm). As the vehicle accelerates or decelerates or alters its rotation, the interference pattern is affected. Because there are no mechanical parts, this reduces “drift.” The quantum INS firm, Q-CTRL, has reported positioning errors as low as 22 meters.

An alternative approach to atom interferometry can be to use noble gas nuclear spin, which detects motion through magnetic-moment shifts of polarized nuclei. These nuclear spins can be polarized (aligned) using a process called Spin-Exchange Optical Pumping (SEOP). In SEOP, alkali-metal atoms (e.g., Rubidium or Cesium) are optically pumped to create a spin polarization, which is then transferred to the noble gas atoms through atom-to-atom collisions.

Which solution is better—atom interferometry, quantum sensors, or noble gas nuclear spin quantum sensors? In fact, they are complementary. Atom interferometry is effective at measuring inertial quantities like acceleration, rotation, and gravity, whereas noble gas nuclear spin quantum sensors are better at measuring rotation and magnetic fields, and are therefore used in gyroscope applications.

What is the outlook for quantum INS sensors? They are still very much at the trial phase. The temperature requirements of atom interferometry quantum sensors will mean that the solution will be bulky, requiring a lot of electricity and insulation. Costs are likely to remain high due to a lack of manufacturing scale. This has not deterred a number of Research and Development (R&D) laboratories and startups from rushing into the technology sector:

• Bosch Quantum Sensing: A subsidiary of German technology firm, Bosch. Partners include Airbus.
• Delta g: A University of Birmingham (United Kingdom) startup targeting underground exploration.
• Exail (previously iXblue): A French company that has a 3-axis quantum inertial sensor for drift-free navigation.
• Infleqtion: A U.S. firm that has partnered with BAE Systems and QinetiQ to demonstrate quantum INS sensors.
• SandboxAQ: The Google startup has developed a solution called "MagNav," which uses quantum mechanics and Artificial Intelligence (AI) for navigation.
• Q-CTRL: An Australian startup that is working with Lockheed Martin on U.S. Department of Defense contracts.
• Vector Atomic: A U.S. startup that has developed an atomic gyroscope for the Defense Innovation Unit (DIU).

The outlook for the sector is very much tied to the development of the quantum materials/quantum computing sector that requires ultra-low temperatures to maintain superpositions. There is significant R&D work in materials and technologies that can maintain superpositions at higher temperatures.

How do end users who rely on PNT solutions resolve these growing GNSS dead zones? The U.S. government has launched its third generation of GPS satellites that incorporate encryption and stronger signal link budgets. The European Union’s Galileo has incorporated multiple frequency support (E1, E5a, E5b, E6), as well as Open Service Navigation Message Authentication (OSNMA) and Advanced Interference Mitigation (AIM). An additional option would be to incorporate PNT solutions from LEO service providers such as Globalstar and Iridium. Terrestrial 5G-Advanced and even AI-enabled optical scanning solutions could further enhance location-based services.