Quantum sensors: measuring the world with quantum physics

Quantum sensors use very small physical systems, such as single atoms, electron spins in a crystal or superconducting circuits, as probes. These systems respond to tiny changes in their surroundings, so they can be used to measure magnetic fields, gravity, rotation and time. One reason to follow the field is navigation. A UK government news release from May 2024 quoted Infleqtion's UK president saying the company's work addressed the need to reduce reliance on satellite navigation (UK government, 2024). A way of finding position and time without satellites could be a backup for aircraft, ships and submarines.

What the term means

Degen and colleagues define quantum sensing as the use of a quantum system, quantum properties or quantum phenomena to measure a physical quantity (Degen et al., 2017). Their abstract names spin qubits, trapped ions and flux qubits as the most common platforms in current research.

Optical atomic clocks are one example. A review by Ludlow and colleagues covers clocks built from single trapped ions and from large groups of neutral atoms. It reports "measurement precision and systematic uncertainty associated with some of the best clocks to date" (Ludlow et al., arXiv preprint, first submitted July 2014). The abstract gives no figures, so none are quoted here.

What has been demonstrated

Here, "demonstrated" means described in peer-reviewed work. Degen and colleagues' peer-reviewed review gives magnetometers based on superconducting quantum interference devices or on atomic vapours, and atomic clocks, as historical examples of quantum sensors (Degen et al., 2017). The abstract does not discuss navigation or use outside the laboratory. We found no peer-reviewed navigation result among the sources checked for this article; the navigation work below comes from a government press release, a company press release and a preprint.

What is reported but not independently checked

A UK flight test (May 2024). The UK government reported that a compact optical atomic clock, the Tiqker, and a tightly confined ultra-cold-atom system were flown on QinetiQ's RJ100 Airborne Technology Demonstrator. The release names Infleqtion, a quantum technology firm, as working in collaboration with BAE Systems and QinetiQ. The final test flight took place on 9 May 2024 at MoD Boscombe Down, as part of a series of test flights whose number was not stated. The release gives no numerical accuracy figures and no flight durations. It says the project received government backing of nearly £8 million (UK government, 2024). The release says the equipment flew. It does not show how well it performed.

Airborne magnetic navigation. A preprint by Muradoglu and colleagues describes a magnetic navigation system built on the authors' own proprietary quantum magnetometers. It reports trials on airborne and ground vehicles, with altitudes up to 19,000 feet. It gives a best final positioning accuracy of 22 metres, or 0.006% of the distance flown, and says the system achieved up to 46 times lower positioning error than a velocity-aided strategic-grade inertial navigation system (Muradoglu et al., arXiv). The abstract does not state the distance flown or say whether GNSS was used as ground truth. We found no journal version of the paper. These figures come from the authors themselves, so they are claims awaiting independent checking.

Clock on an uncrewed submarine (October 2025). Infleqtion's press release, dated 28 October 2025, says the trial, with the Royal Navy and MSubs, used its Tiqker clock on the Royal Navy's Excalibur uncrewed testbed submarine and confirmed that the clock could operate reliably during "multiple dives" (Infleqtion, 2025). The release gives no dive count, trial dates or measured results. It describes the clock's performance as "equivalent to a national laboratory-grade time reference" without showing measurements, and says benchmarking against high-grade time standards will follow. A Royal Navy officer, Commander Matthew Steele, called the experiment "a first critical step".

Limits and open problems

• Size, power and cost. The sources we checked give no size, power or cost figures for these systems, so we cannot put numbers on them here.
• Independent testing. We found no independent measurement of navigation error against known positions in the pages we checked. The navigation figures we found come from the preprint's authors, not from an independent test.
• Environmental conditions. The pages we checked do not quantify the temperature, vibration, shielding or magnetic noise limits these instruments need, so this article does not give figures for them.
• Approval. We did not find any source showing that an aviation or maritime authority has approved a quantum sensor as a navigation source.

Speculative uses

Several uses are often proposed. These include navigation for ships and vehicles in areas where satellite signals are weak, mapping underground structures from very small changes in gravity, and wearable magnetic sensors for medical imaging. None of these is shown by the pages we checked, so treat them as ideas for the future rather than near-term products. The medical idea is a research proposal only. This article is not medical advice, and none of the sources we checked describes a quantum sensor approved for diagnosing or monitoring any condition.

What to watch next

• Independent flight or sea trials that report position error against a known reference, with the conditions stated.
• Peer-reviewed publication of the magnetic navigation results, or a repeat of them by another research group.
• Benchmark results for the Tiqker clock against high-grade time standards.
• Any aviation or maritime regulator accepting a quantum unit as a navigation source.