Okay, I think I can work with this: www.whitehouse.gov/wp-content/u...
Reminder to re-brand all #NMR research as #Quantum
Turns out inductive (“normal”) NMR can only measure spin noise because it is amplified by radiation damping. Because NMR probes are high-Q tuned resonant circuits, any small nuclear magnetization signal induces a small current in the circuit, and this current then acts on all the spins in the sample
So inductive #NMR can indeed measure the signal from 10^10 spins, but only if there are 10^20 identical ones around to help amplify the signal