In the event of a conflict or confrontation, the joint and allied force could lose access to satellite capabilities, most notably GPS. Ships, submarines, and aircraft would need to rely almost entirely on other technologies for positioning, navigation and timing (PNT), particularly inertial systems.
Unfortunately, because inertial navigation devices such as gyroscopes and accelerometers lose accuracy over time—and wouldn’t be able to be recalibrated in a GPS-denied environment—inertial navigation would be reliable for only a limited period.
But an emerging technology, quantum sensing, offers the possibility of increasing the accuracy of inertial navigation by orders of magnitude, greatly extending operational availability in GPS-denied environments.
The idea behind quantum sensing is fairly straightforward. Essentially, quantum refers to the realm that exists at the atomic and sub-atomic level. That realm is extremely sensitive to minute changes in the environment—changes that cannot be detected in the everyday world. Quantum sensing harnesses that sensitivity, allowing measurements that are far more precise than what is possible through conventional approaches.
Although using quantum for inertial navigation is a technology of the future, that future may not be far away. Quantum sensing is already used in atomic clocks—including in military satellites—and in devices such as MRI machines. Government and private researchers are making rapid advances in quantum sensing for inertial navigation, and some devices may be ready for deployment by the military in as little as five years, according to the NATO Review.
For that to happen, however, defense organizations need to take steps now to make sure that the quantum gyroscopes and other devices being developed are practical for current and future ships, submarines, and airplanes. Quantum sensing devices typically require a great deal of size, weight, and power, and researchers are now focusing on ways to make them work for the Navy and other services.
It’s important that defense organizations develop deep expertise in quantum sensing, and take the lead in driving the requirements, so that the quantum devices can be deployed as soon as possible. China is now aggressively pursuing quantum sensing for inertial navigation, and could leave the U.S. behind.
HOW QUANTUM SENSING WORKS
The behavior of atoms, particles of light, and other denizens of the quantum realm can reveal a great deal about what is happening in the larger physical world. For example, when a cloud of atoms inside a vacuum is in an excited state, the atoms become highly sensitive to the gravitational field around them. By looking at the patterns the atoms form, quantum devices can create a picture of the gravitational field around a ship or submarine. With repeated readings as the ship moves, that picture becomes increasingly detailed. Onboard computers can then overlay the picture with maps of Earth’s gravitational field to determine the ship’s precise location.
An entirely different type of quantum sensing can measure the surrounding magnetic field, also helping to plot a ship’s location. With a quantum magnetometer, a tiny wire made of special materials is made so cold that it has virtually no electrical resistance. This eliminates “noise” on the wire, so that when an electrical charge is sent through it, the wire becomes highly sensitive to the magnetic field at the atomic level. The device takes a series of measurements to determine the surrounding magnetic field, which can then be compared to magnetic field maps of the world.
Additional types of quantum sensing can aid other aspects of inertial navigation. A quantum gyroscope, for example, uses the wave nature of atoms to measure angular rotation. An atomic clock sets its watch by the predictable rate that excited atoms decay. A quantum accelerometer measures the movement of super-cooled atoms.
What all these quantum devices have in common is that they are self-contained and completely independent of GPS or other outside communications. In addition, because measurements in the quantum realm are far more accurate than with conventional approaches, quantum inertial navigation can be relied upon for much longer periods.
MOVING FROM THE LAB TO THE REAL WORLD
While quantum sensing devices have been proven to work, with the exception of atomic clocks they are generally too large to be of practical use for inertial navigation. For example, the refrigerators needed to supercool the wires in quantum magnetometers can take up a great deal of space—and what works in a laboratory may not fit on a submarine. In the lab, some optics-based quantum sensors feature a collection of mirrors, glass plates, lasers, and various electronics that sit on a platform the size of a dining room table.
Much of the research now being done on quantum sensing, including in DoD laboratories such as the U.S. Naval Research Laboratory, is focused on how to make the devices small enough to fit on ships, submarines, and airplanes without a significant drop-off in accuracy and precision.
A key challenge is that it’s often difficult to determine how well a smaller and lighter device, with reduced power requirements, will perform until it has been built. In addition, each type of quantum sensing device has its own complex set of trade spaces. Manufacturers may have to experiment with a number of prototypes to get the right balance of size and performance. This process might in some cases be too costly to be feasible—and too time-consuming for the DoD to keep pace with adversaries in the race for quantum sensing.
One solution is for defense organizations to use modeling and simulation to test how particular quantum devices would work in the real world. This can be done by building models based on research data. Many research papers have been published describing different approaches to quantum sensing devices, and this information— along with data from various prototypes that have been built so far—can be used to build the models.
By continuing to play a major role in the ongoing research—including with modeling and simulation—the joint force can gain the information and expertise needed to drive the requirements for quantum sensing, rather than relying entirely on industry. Such an approach can significantly speed the adoption of quantum sensing for inertial navigation, helping to extend operational availability in GPS-denied environments.
Kevin Coggins ([email protected]) is a Booz Allen vice president working across the complex landscape of weapons systems, critical infrastructure, cyber, space and intelligence—including leading the firm’s PNT business. His journey as a force recon Marine, weapons system engineer, tech startup founder, Army SES and industry executive has enabled a unique perspective on solving the myriad of technology challenges facing the warfighter.
Dr. Jake Farinholt ([email protected]) is a senior lead scientist at Booz Allen, where he leads the firm’s overall quantum business in the national security sector, as well as the firmwide quantum sensing business. For more than a decade, he has provided expertise in quantum technologies to the intelligence community, as well as to the Navy and other defense organizations.
Dr. Oney Soykal ([email protected]) is a physicist at Booz Allen specializing in quantum computing. He develops quantum systems for research in academia, industry, and government, and provides technical analysis and management support to multiple DARPA and IARPA programs.