Quantum Tech for Positioning, Navigation, and Timing

A working GPS is ultimately reliant on both orbiting satellites and accurate timing. Harnessing time-stamped and location-stamped signals received from nearby satellites, a GPS uses the time it took for the signal to reach it to calculate its distance from the satellites. Combined with information on the satellites’ locations, a GPS determines its own position. Any mistakes in timing can lead to errors in determining position, thus ruining any chance of using a GPS for navigation.

To maintain accuracy, GPS satellites carry precise atomic clocks, which are periodically re-synchronized with a “master clock” on Earth to correct for small errors that gradually accumulate. Improving the precision of atomic clocks or the precision of their synchronization would push GPS past current limits in accuracy.

Modern atomic clocks build on the original GPS atomic clocks through their compatibility with high-precision quantum synchronization protocols. Quantum clock synchronization begins with clocks that connect to one another with uniquely quantum interactions. These “quantum connections” make the clocks’ properties interdependent, regardless of their separation. The clocks can exploit this dynamic to achieve robust and high-precision synchronization between satellites and an Earth-bound master clock. As a bonus, current GPS-receiving devices—like a smartphone or car GPS—would not require any modification to harness this upgrade.

Challenges are inherent in creating and maintaining the delicate quantum connections between satellites and Earth—yet they are worth tackling. Bringing precision from the scale of 10 feet down to 1 foot or less would open GPS to new civilian applications in surveying, precision agriculture, and robotics. It would further applications such as weapons targeting and reconnaissance for the military. Improvements in timing would similarly strengthen civilian infrastructure in applications such as communication, utility distribution, and coordination of large-scale financial transactions.

Inertial navigation systems are already known as a potential complementary approach to GPS. Instead of satellites, these systems use accelerometers and gyroscopes to measure changes in motion, and they calculate position based on a previously known location. However, traditional devices accumulate errors too quickly to be practical for most applications. Quantum technologies offer a new solution to this problem.

The leading quantum accelerometers sense motion by leveraging how quantum particles, such as atoms, can behave as waves, like sound or ocean waves. When two waves overlap, they combine to make a new wave. The same is true in the quantum case; forcing atoms to accelerate changes the shape of the combined wave. By measuring the shape of the newly combined wave, the accelerometer can deduce its acceleration. Because the atoms are extremely sensitive to minute changes, quantum accelerometers achieve levels of sensitivity and accuracy that are not possible with traditional systems.

Quantum accelerometers are in the early stages of commercialization, and full quantum inertial navigation systems are likely not far behind. The high sensitivity of quantum accelerometers means their positioning information remains accurate about ten times as long as that of their non-quantum counterparts. This enables accurate, independent positioning for much longer periods before recalibration becomes necessary. Such independence is key wherever GPS signals cannot reach the receiving device, such as underwater, underground, or as a result of adversarial jamming. Furthermore, when both GPS and quantum inertial data are available, they can cooperate as a single system with higher precision than either would have alone.

Written by Isabella Martinez and Dylan Rudy