What Is Quantum Sensing? Where the Technology Stands in 2026

Quantum sensing is measurement done with single atoms, electrons or particles of light. Each one reacts to time, gravity, magnetism or motion in a way that nature fixes, so a sensor built on them does not drift like a spring or a quartz crystal. That is the appeal. The catch is that the same sensitivity makes them easy to upset.

Some of it is old and everywhere. Every GPS satellite carries atomic clocks, which the US aviation regulator says keep time to at least a billionth of a second. The newest and most active work is navigation for when satellite signals are jammed or faked. Since 2024 Boeing with AOSense, Infleqtion, Q-CTRL and SandboxAQ have tested quantum navigation and timing kit on aircraft, ships, drones and a submarine.

A quantum sensor reads the world from the state of single atoms

Atoms behave like perfect, identical tuning forks. Each kind has energy levels a fixed distance apart, and light or radio waves at exactly the right pitch make it jump between them. A clock locks onto that pitch. A magnetometer, a device that measures magnetic fields, watches how a field shifts those levels. A gravimeter, which weighs the local pull of gravity, drops a cloud of cold atoms and times their fall.

The quantum trick is superposition, an atom being in two states at once until it is measured. A sensor puts each atom into two states and lets the outside world push on them slightly differently. Then it brings the two back together. The gap shows up as a change in how many atoms land in each state, an effect called interference, and it can reveal a push far too small for a spring to feel. Some sensors go further and use entanglement, a link between particles that lets a group measure more finely than the same number working alone.

That sensitivity has a price. Heat, shaking and stray fields upset the delicate state long before the signal does, so most quantum sensors need lasers, vacuum chambers and shielding. DARPA, the US defence research agency, put it bluntly when it began a programme in August 2025 to fix the problem. It said their sensitivity has made quantum sensors “notoriously fragile in real-world environments”. Much of the work in the field is about keeping the world out while letting one quantity in.

Atomic clocks are the quantum sensor the world already depends on

Atomic clocks are the oldest and most successful quantum sensor. The second itself is defined by the caesium atom, whose natural frequency is fixed at 9,192,631,770 cycles a second. Satellite navigation is built on these clocks, because a receiver works out where it is by timing the signals that arrive from several satellites at once. That only works if the clocks on board agree to within a billionth of a second, and every phone and car that uses GPS relies on them.

Clocks are also the part of the field closest to the shelf. Microchip sells a chip-scale atomic clock small enough for a circuit board, aimed at military radios and sensors. At the far end, a strontium clock at JILA in Colorado reported an uncertainty of 8 × 10⁻¹⁹ in 2024. That was the lowest yet reported for any clock. Optical clocks like it tick on light rather than microwaves and are far more precise than caesium, but they have been large and delicate until recently.

The next step is to make them portable. Infleqtion’s Tiqker optical clock was tested aboard a Royal Navy uncrewed submarine in October 2025, which the company calls the first such test on an underwater drone. A submarine cannot receive GPS under water. The clock does not tell the vehicle where it is, but it holds accurate time, and the navigation system uses that time to stay accurate for longer between trips to the surface.

Quantum magnetometers have reached clinics, inside shielded rooms

The magnetometer is the second family to find paying customers. One kind, the optically pumped magnetometer, shines a laser through a tiny glass cell of heated metal vapour. The laser lines up the atoms’ own small magnets, and any outside field tips them over, which changes how much light gets through. These sensors work at room temperature. They are small enough to sit in a helmet.

That has changed brain scanning. The older method, known as MEG, picks up the brain’s faint magnetic signals with sensors that must be chilled close to absolute zero inside a fixed helmet. In 2018 a team led from the University of Nottingham showed a wearable version in Nature, with volunteers nodding, stretching and even playing a ball game during the scan. The spin-out Cerca Magnetics now sells it, built with the sensor maker QuSpin and Magnetic Shields Limited. It installed a 128-channel system at the charity Young Epilepsy in Surrey in September 2021 to scan children.

The limit is the room around it. The sensors need the Earth’s own magnetic field cancelled around the head, so each scanner comes with shielding, and a compact shielded room was one of Cerca’s first steps. That keeps these scanners in hospitals and research centres. It is still a large gain over machines that need liquid helium.

Diamond is the other route. A nitrogen-vacancy centre is a flaw in diamond where a nitrogen atom sits beside a missing carbon atom. It acts as a tiny compass needle that can be read with light at room temperature. Qnami, a Swiss firm, sells microscopes that run a diamond tip across a sample to map magnetic patterns at the nanoscale. The US instrument maker Quantum Design bought Qnami in May 2026. Bosch wants to take diamond sensors into industry. It set up an in-house start-up in 2022, and in April 2025 turned it into a joint venture, Bosch Quantum Sensing, with the diamond maker Element Six holding 25 per cent.

Cold-atom gravity sensors are on sale, and the same physics is learning to navigate

An atom interferometer is a quantum ruler for motion. It cools a cloud of atoms with lasers, splits each atom’s state in two with pulses of light, and lets the halves travel slightly different paths. When they are put back together, the result shows how hard the cloud was pulled. Measure the fall and you have weighed gravity. Measure it in a moving vehicle and you have a motion sensor that does not drift.

Exail, a French firm, sells an Absolute Quantum Gravimeter that it says measures gravity at a level of 10⁻⁸ metres per second squared. That is about a billionth of the pull we feel at the Earth’s surface. Exail says the instrument installs in 20 minutes with no optical alignment, is sold for geophysics, measurement labs and construction, and spent a year on Mount Etna helping to watch the volcano.

A gravity gradiometer measures how gravity changes from one spot to the next. That shows what lies underground. Delta g, a University of Birmingham spin-out, raised £4.6 million in September 2025 to run trials with partners such as the UK’s transport ministry, which is in charge of roads and rail.

Navigation is the bigger prize. An inertial navigation system tracks position by adding up every push and turn since the last known fix. Ordinary ones drift, so small errors pile up over hours of flight. Boeing flew a quantum inertial unit built with the Californian firm AOSense in 2024 and navigated without GPS for four hours. Boeing says such units could cut the error at the end of a long flight from tens of kilometres to as little as tens of metres. That is a forecast. It is not yet a result in service.

Satellite jamming has turned quantum navigation into a defence race

The demand comes from jamming. Satellite signals reach the ground very weak, so a cheap transmitter can drown them out, and a cleverer one can feed a receiver false positions, which is called spoofing. Europe’s aviation regulator and the airline body IATA said in June 2025 that GPS signal loss events rose by 220 per cent between 2021 and 2024. That is a count of events in IATA’s own flight data, not a rate per flight, and 2021 was a weak base, with passenger traffic 58 per cent below its 2019 level. A study for the British government puts the cost of losing satellite navigation for one day at about £1.4 billion, and for a week at about £7.6 billion.

Two kinds of quantum navigation are competing. The first matches what a sensor feels against a surveyed map of the Earth’s magnetic field or gravity, much as a walker matches hills to the contour lines on a chart. The second is a drift-free motion sensor, which needs no map at all. Map-matching is closer to market. The quantum part is the sensor, and SandboxAQ says its AQNav system uses quantum-based magnetometers because they can turn the Earth’s weak magnetic signal into an accurate position.

Q-CTRL, an Australian firm, sells a map-matching system called Ironstone Opal. It is qualified to DO-160G, the test standard for kit carried on aircraft. That is a step towards routine use. In August 2026 Q-CTRL said a version built around a quantum gravimeter kept a ship within one nautical mile in trials in the Coral Sea. That beat navigation-grade backups by more than ten times, the company said. DARPA has also given Q-CTRL contracts worth about US$24 million under the programme it began to make quantum sensors tough enough for military vehicles.

Other firms are in the same race. Safran Federal Systems won a contract under that DARPA programme in October 2025. SandboxAQ collected more than 150 hours of flight data across 200 US airports with Acubed, Airbus’s Silicon Valley lab. In September 2026 it flew its AQNav software on Northrop Grumman’s Lumberjack, a low-cost drone built to be expendable. SandboxAQ describes the system as passive, because it reads the ground rather than listening for satellites, so there is no signal for an enemy to block.

Britain has made this a national goal. Its quantum strategy includes a mission to deploy quantum navigation systems on aircraft by 2030. In May 2024 a team led by Infleqtion flew an optical clock and a cold-atom sensor on a QinetiQ test aircraft, backed by nearly £8 million of public money. The government called these the first flights of their kind to be publicly acknowledged anywhere. In June 2026 Aquark Technologies ran its third trial with the Royal Navy, using two of its cold-atom clocks to keep a network of radars in time without satellite signals. Both clocks reached a usable signal from cold in less than 30 minutes.

Quantum radar remains lab work, while squeezed light already helps LIGO

Not every quantum sensing claim has survived contact with the field. Quantum radar would send out one half of an entangled pair of microwave photons and keep the other, then use the link between them to pick a faint echo out of the noise. The best-known experiment, published in 2020, beat a matched classical radar in a test at a distance of one metre, and its edge showed mainly at very low power. Its authors pointed to short-range uses such as medical scanning. Even Aquark, which builds quantum clocks for radar, calls this kind of radar controversial among engineers, both for whether it can work at scale and for what it would give users.

Quantum light does have one celebrated success. The LIGO detectors, which sense gravitational waves from colliding black holes and neutron stars, use squeezed light, light whose random flicker has been reduced in one property at the cost of another. In 2023 the LIGO team reported that squeezing raised the rate at which they can detect events by up to 65 per cent. It needed a 300-metre filter cavity added to each detector, which shows how much effort a real quantum gain can take.

Sensing needs a few well-behaved atoms, not a quantum computer

People often confuse quantum sensing with quantum computing, because both depend on fragile quantum states. Their goals run in opposite directions. A quantum computer must shield its qubits, the basic units of quantum information, from the outside world while it works. A sensor wants the outside world to reach its atoms, as long as only the one quantity being measured gets through and everything else stays out.

That difference explains why sensing is ahead. A clock or a gravimeter can work with a cloud of identical atoms all doing the same job. A useful quantum computer needs many qubits that each hold different information, plus error correction, a way of spotting and fixing mistakes as they happen, and that is still being built. A quantum sensor is useful the day it beats the classical device it replaces. Our guide to quantum computing covers the other side of the field.

Ruggedness, size and maps still keep most quantum sensors in trials

Three limits stand between these sensors and routine use. The first is ruggedness. DARPA’s programme exists because shaking and stray fields still spoil quantum sensors on moving vehicles, and its first round put test units on a helicopter for exactly that reason. The second is size. Cold-atom devices still need lasers, a vacuum chamber and racks of electronics, which is one reason map-matching software is reaching aircraft before fully quantum motion sensors do.

The third limit is the map. A magnetic or gravity navigator is only as good as the survey it compares against. SandboxAQ stressed that its tests ran over both rugged mountains and flat, featureless plains, because the strength of the pattern varies so much from place to place. Most of the accuracy figures published so far come from the companies themselves, so buyers should ask for results from government test ranges before treating any figure as settled.

The clearest market forecast comes from a seller, and one supplier has already failed

Reliable figures for what quantum sensing earns today are hard to find. The clearest forecast comes from Bosch, which puts the yearly market for medical and mobility uses alone at mid-single-digit billion euros a year by the middle of the next decade. That is a forecast from a company that sells the sensors. It covers only two markets and leaves out defence and timing, which drive most of the trials described above.

Not every firm will survive the wait. M Squared Lasers of Glasgow went into administration in August 2025 with the loss of 28 jobs. Insider Media, which called it a photonics and quantum technology specialist, said it had faced mounting money pressures and a cash shortfall. Quantum sensors depend on small specialist suppliers like it, and when one of them fails, the labs and start-ups that bought from it have to look elsewhere for parts.

Buyers can use quantum timing now and should plan quantum navigation for 2030 and after

For a business, the question is which quantum sensor to buy now and which to watch. Atomic clocks are mature, and any firm that needs accurate time without trusting satellites can buy one today, in sizes down to a chip that fits on a circuit board. Brain scanning with optically pumped sensors is a working clinical and research tool. Cold-atom gravity surveys are a small market.

Navigation is different. Buyers should stop treating companies’ own trial accuracy figures as procurement-grade, and stop ranking quantum navigation as a replacement for GPS rather than a backup. The trials are impressive, but none of these systems is yet standard on a commercial aircraft, and Britain’s own target for putting them on aircraft is 2030. A defence or aviation buyer should plan for it as a backup, run trials on its own platforms and judge it on independent tests. For the companies behind all of this, our guide to quantum sensing companies goes further.