Fragility as a superpower
The same sensitivity that makes qubits terrible at staying coherent makes them extraordinary detectors. Quantum sensing uses superposition, coherence, squeezing and entanglement to measure time, acceleration, gravity, magnetic fields, electric fields and other quantities with exceptional precision. Unlike universal fault-tolerant computing, many sensing applications do not require millions of error-corrected qubits. That is why sensing is likely to commercialize first.
Where it lands
Navigation without GPS (inertial sensing when satellites are jammed or unavailable), geophysical mapping (gravity sensors seeing what's underground), medical imaging (magnetometers reading heart and brain fields), timing (the atomic clocks that already make GPS possible), diagnostics, and detection of weak fields. Atomic clocks are the proof that this industry is real: quantum sensors have been quietly load-bearing for decades.
La métrique pertinente est la sensibilité dans des conditions réelles de fonctionnement : pas seulement la précision en laboratoire.
Deeper treatment
Metrology, squeezing and the engineering economics of the sensing pathway: advanced Academy module Quantum Security, Networking, and Sensing.