Quantum Accelerometers Could Enable GPS-Free Navigation for Underground Trains

Tube trains of the future may soon know exactly where they are underground — even in places where GPS is blind — by tapping into the strange rules of the quantum world.

Most modern tracking systems rely on satellites to pinpoint location, backed up by accelerometers that measure tiny movements between GPS updates. It works well enough above ground, but those accelerometers gradually drift, which is why they constantly need satellite corrections.

However, in tunnels or urban areas surrounded by tall buildings where GPS signals don’t reach, that safety net disappears.

The quantum accelerometer works by using ultra-cold atoms that are extremely sensitive to acceleration. By measuring how these atoms move when the device accelerates, it can calculate position with incredible precision.

This technology could transform how we navigate underground transportation systems, making them safer and more efficient.