> The detector elements of a camera could be made pretty sensitive, but they can't detect fewer than one photon.

Or can they?

If the detector elements were part of a quantum computer (or a quantum computing "chip", whatever that will turn out to be) they would be able to analyze all the photon paths (Feynman paths) bouncing back from the subject, even those that would decohere / collapse away in a traditional detector.

IANAP, but wouldn't a quantum chip be able to perform some amount of NLOS by analyzing the paths of even a single photon?