Quantum Sensors Have Potential to Replace GPS.

• Author: Tegler, Jan

Researchers in government and industry laboratories across the globe are in a race to refine technology and methods for detecting changes in motion and electric and magnetic fields at the atomic level.

Spotting minute changes in the known properties of atoms can yield extremely precise and accurate measurements --a technique known as quantum sensing.

While suitable for a range of applications, quantum sensing for navigation is an area of prime interest for the Pentagon. U.S. warfighters routinely train for operations in GPS-denied environments as realization has grown that technologically sophisticated rivals like China or Russia can corrupt or disable the GPS signals the U.S. military relies upon.

Work done by Naval Research Laboratory research physicist Roger Easton was foundational for GPS, leading to the launch of NTS-2, the first satellite to transmit GPS signals in 1977. Today the NRL's Section Head in Quantum Optics, Adam Black, is among those adapting quantum sensors for an alternative navigation technique that predates GPS--inertial navigation.

"I think that with some of the smallest atomic inertial technologies we might only be a few years out from something like that," Black said, describing quantum inertial measurement units that could be much smaller than the large, fixed equipment currently used for quantum sensing research and development in laboratories.

Inertial navigation employs accelerometers, gyroscopes and a computer

--known collectively as an inertial measurement unit, or IMU--to continuously calculate the position, the orientation and velocity of a moving object without the need for external references. In use for military aircraft and weapons guidance since the 1960s, the technology was supplanted by GPS by the early 1990s.

Less vulnerable to disruption than GPS, inertial navigation using quantum sensors is viewed as a way to navigate with similar or better accuracy than GPS when compromised or unavailable.

One of the biggest hurdles to quantum sensing devices that could be used in dynamic environments like military ships, submarines or aircraft is making them small enough and energy efficient enough to be suitable for these platforms. Downsizing the quantum sensors developed so far also diminishes their accuracy and precision. It's a "tradeoff but a tractable challenge" that NRL, the Army and Air Force Research Laboratories and researchers in private industry are working on, Black explained.

"You can imagine a...