Quantum computers get all the hype, but quantum sensors could be equally transformative, enabling autonomous vehicles that can “see” around corners, underwater navigation systems, early-warning systems for volcanic activity and earthquakes, and portable scanners that monitor a person’s brain activity during daily life.
Quantum sensors reach extreme levels of precision by exploiting the quantum nature of matter—using the difference between, for example, electrons in different energy states as a base unit. Atomic clocks illustrate this principle. The world time standard is based on the fact that electrons in cesium 133 atoms complete a specific transition 9,192,631,770 times a second; this is the oscillation that other clocks are tuned against. Other quantum sensors use atomic transitions to detect minuscule changes in motion and tiny differences in gravitational, electric and magnetic fields.