You’re calculating based on classical mechanics. The sensors are optical-atomic magnetometers, using quantum mechanics to measure magnetic vector potentials (MVP), which behave differently and can produce seemingly non-local effects (Aharonov–Bohm effect).

> A magnetic dipole doesn't radiate energy outward the way a radio antenna does.

See Section 15-5 of https://www.feynmanlectures.caltech.edu/II_15.html#Ch15-S5

Veritasium has a video on the weirdness of MVP: https://m.youtube.com/watch?v=XKSjCOKDtpk

See https://pubs.aip.org/aip/adv/article/13/2/025127/2877320/Dif... for an experiment measuring MVP with an optical-atomic magnetometer.

> Oh, but you say that you simply cool the sensor to 0K.

These sensors do not require cryogenics and have been developed with sensitivities of 10s of fT/√Hz, so approaching the quantum noise limit.

Essentially, you can think of it as measuring the energy of a magnetic dipole in space instead of measuring a magnetic field.