Commentary Quantum sensors are creating a commercial revolution
Quantum sensors use the fundamental properties of atoms and light to make measurements of the world. The quantum state of particles is extremely sensitive to their environment, which is an advantage for sensing but a problem for building quantum computers. Quantum sensors that use particles as probes can quantify acceleration, magnetic fields, gravity and the passage of time more accurately than those designed or classical devices based on chemical or electrical signals. They could be used to make smaller, more accurate atomic clocks, cameras that can see through fog and around corners, devices that can map underground structures, and many other potential applications. Even more, they will be able to transform many sectors: from energy, land use and transportation to health care, finance and security.
A quantum sensor developed by the U.S. Army in 2020 could detect communication signals across the radio spectrum.
However, their commercial prospects need to receive more attention.
An existing challenge is that it is difficult to predict exactly how, and where, emerging technologies will be adopted. The history of physics is full of serendipitous inventions. X-ray generators, for example, were an accidental byproduct of "experiments to see if an electron beam could pass through glass," but they are now vital to medicine and airport security; Theodore Maiman, the inventor of the laser, described the technology as "a solution in search of a problem ".
Another big challenge is that many people (including business leaders) see quantum technology as a device of the future, not the present. Unlike quantum computers, which have received a great deal of media coverage and may be decades away from widespread "commercial advantage," quantum sensors are already in use in the laboratory. Even a few are already in commercial use: for example, atomic clocks use high-frequency quantum transitions in atoms to measure the passage of time with extreme precision; their accuracy maintains the synchronization of communications, energy networks, and digital broadcast stations. As such, they are critical to satellite navigation services such as GPS.
Even so, it took 20 years for GPS receivers to evolve from specialized devices used by the military, (tech-savvy) hikers, and ship captains to provide navigation for smartphones and cars. Now, the quantum community needs to establish similar pathways to realize the commercial benefits of other types of quantum sensors.
Quantum gravity sensors and quantum gas detectors flown on satellites could collect accurate data on groundwater, carbon dioxide and methane levels for improved climate modeling. Quantum magnetic sensors can image people's brain signals in real time, and quantum gravimetry can monitor groundwater levels and volcanic eruptions. For example, combinations of quantum sensors that track gravitational gradients, magnetic fields and inertial forces are 1000 times more accurate than classical sensors, allowing reliable navigation in places where satellite signals are jammed or inaccessible, such as remote areas, conflict zones or underwater.
So what are the priorities for commercializing quantum sensors and getting them adopted more quickly?
Innovators in industry rarely get excited about the lab results of a simple proof of concept; they want to know if a device will work reliably in a given application and will benefit the financial position of the business. Researchers need to ensure that any sensor that comes to market is robust and reliable, can be manufactured in a reproducible and cost-effective manner, and is compatible with other systems in use. In practice, this can mean redesigning many aspects of the technology; certainly, each adjustment brings new challenges.
For example, in the Sensors and Timing Laboratory at the UK Centre for Quantum Technologies in Birmingham, scientists have developed a sensor to measure gravity gradients: in two rooms 1 meter apart, lasers capture rubidium atoms from vapor and cool them to rest; more laser pulses produce a superposition of quantum states and for each "cloud " in each "cloud" reads out these signals. Software converts these signals into gravity gradient measurements; by using a single laser beam to manipulate the atoms, this quantum device is 1000 times less sensitive to vibrational noise than conventional gravimeters, making it easier to deploy.
A diamond-based quantum sensor can measure magnetic fields at the atomic scale.
The version first demonstrated in the lab was the size of a minivan and a lab table filled with shelves of optical components, electronic systems and power supplies. It was built from custom parts and tuned by hand. To take this device out of the lab and sense underground tunnels through small changes in local gravity means scientists need to make all the components stronger, smaller, cheaper, and improve their performance.
Our physicists and engineers must find ways to control the laser beam at different temperatures, place it in a vacuum to avoid air turbulence, and pulse the laser to reduce the effects of stray magnetic fields. Work is underway to operate the device on a mobile platform to facilitate deployment, increase its sensitivity and bandwidth to speed up mapping, and reduce its size to the size of a backpack so it can be mounted on a UAV for large-area measurements.
One promising path to miniaturization is the integration of quantum sensors in photonic microchips. These sensors rely on light (photons) rather than the electrons used in traditional microchips, and are fast and energy efficient. Similar technology is available in fiber optic networks. Quantum sensors can be miniaturized using photonic chips and existing manufacturing processes for microelectromechanical systems (MEMS) used in automotive airbags. The advantage of this is that they are robust and can cope with vibrations better than bulkier optical systems can.
The challenge is to integrate all the elements into one system: including lasers, modulators, waveguides and beamsplitters, as well as components such as vapor cells. Scientists need further research and investment in new materials, manufacturing techniques, device packaging, and testing and verification procedures. Standardization of quantum sensor technology, one of the low-cost building blocks, is also urgently needed, in line with the progress of fiber optic communication and MEMS sensor technology.
Researchers need to talk to business leaders to determine how quantum sensors can add value in a range of applications.
For example, the use of gravity sensors is not obvious; few people use gravity or the density of materials to sense their surroundings. But after discussions with more than 100 companies, we (scientists at the University of Birmingham, UK) have concluded that gravity sensors are great for illuminating unknowns in the ground: this includes the location of forgotten mines, groundwater levels, and the distribution of carbon in soils and lava flows. In principle, these can all be seen with classical gravimeters, but ground vibrations make their measurement process unfeasibly long: typically one data point takes 5-10 minutes; with quantum gravity gradiometers, such data can be collected in seconds, opening up the potential for gravity mapping.
-- and that's just what scientists have focused on so far.
The illustration shows an optical clock in which strontium ions are oscillating under the light of a laser.
Of course, we need funding for applied research and multidisciplinary collaborations between academia and industry to validate these ideas. In some cases, the next step involves geophysical studies using such gravimeters to improve understanding of how water flows and accumulates underground - information that can be used to refine flood models.
We also need civil engineering studies on how best to use such sensors to detect leaks in water pipes; broader technical and economic considerations will determine how best to use this approach in water management.
Companies should begin to consider new business models (such as providing subsurface mapping services to farmers) to help reduce irrigation water use. Participating in pilot projects will put companies in a good position to take advantage of market disruptions - rather than being trapped by them.
The raw data from the sensors needs to be transformed into information useful for a specific task. For example, while a quantum magnetic field sensor can detect tiny fields associated with neural activity patterns in the brain, three-dimensional visualization of brain activity requires an array of such sensors, as well as algorithms and graphical representations that allow physicians to display them in an interpretable manner.
Development of such a system is underway and could revolutionize the understanding of brain conditions. Real-time mapping (e.g., 100 scans per second) and analysis of the brain's response to visual or sensory stimuli may replace current techniques for diagnosing brain disorders based on patient questionnaires; it may also allow physicians to assess the efficacy of drugs for brain disorders on an individual basis.
A researcher at Q.ANT, Germany, examines a quantum sensor ready for industrial use.
Again, advanced analysis techniques are needed to extract three-dimensional subsurface images from gravimetric measurements; only, determining the depth of the sensed object remains a challenge. Radar libraries driven by quantum oscillators need to be networked to display detailed images, rather than dots on a radar screen (as needed to classify and distinguish drones from birds flying over cities, for example). Big data technologies must be deployed to collect all this information for multiple applications such as monitoring the tens of thousands of delivery drones in the city.
Perhaps the biggest data challenge in terms of time and effort is creating "training" datasets through experimentation. Researchers will need to conduct large-scale medical trials to find biomarkers of brain disease, collect data from a network of gravimeters to understand groundwater and other assets, and acquire radar data through a network of sensors throughout the city.
Scientists have also called for more such programs to be funded by the government.
While many countries have begun to coordinate efforts to develop basic quantum technologies, there are still divergent approaches to adopting and utilizing the technologies. Addressing the research challenges outlined earlier will take decades as many groups work in isolation. To accelerate progress, a strategic plan for coordinating quantum sensor research projects is needed.
Several countries (including Germany, Japan, the Netherlands, the UK, and the US), have established centers and large programs to coordinate academic and national needs in quantum technologies by bundling expertise and providing portals to interact with industry and other partners. In general, however, sensors have not received the attention they deserve in national quantum technology initiatives, with a few exceptions: such as the QuantumBW initiative in Baden-Württemberg, Germany, which is explicitly focused on quantum sensing.
Governments need to put in place policies and regulations to support innovation in quantum sensors, with a focus on enhancing the management and security of national critical infrastructures. For example, a 2020 presidential order requires U.S. national aviation authorities to achieve GNSS-independent timing by 2025; this will ensure that air traffic control systems continue to work, even if they are subject to failure due to accidental or hostile intervention. It is too early to determine the impact, but the order has set boundary conditions for the emergence of commercial ideas related to timing technology.
Similar approaches in communications, water management and medicine may encourage the adoption of quantum sensors in these sectors, making them more "resilient" - by having independent timing and navigation or more detailed data.
At the same time, there needs to be initiatives where companies, from component manufacturers to system integrators, can work with academia to help find commercial solutions (rather than simply proposing technologies) and then rapidly scale up production in the hope that there will be a market for them. One promising effort is the UK's National Quantum Sensor Accelerator (Accelerator) project. Launched in 2022 and still not fully funded, the project involves three globally influential corporate giants (BAE Systems, BP and British Telecom) and aims to bring in additional companies. While other countries' initiatives target quantum technologies in general (such as QED-C in the US), the UK program is unique: because it focuses on sensors.
In short, we urgently need a long-term, industry-led approach to quantum sensor innovation. It is true that the physics of quantum sensors can provide extremely high performance, but the question is: who will lead the world in providing these benefits?
