Physicists Measure Elusive 'Persistent Current' That Flows Forever

Indeed, current is quantized, and the zeroeth state will still carry current (evidently without resistance). It should be bidirectional (i.e., a spin of +/- hbar/2), so could be used as a qubit. Maybe a little too sensitive to external perturbations to be useful though.

I'm guessing they made their measurement as a sort of combination of Millikan Oil Drop and NMR spin experiments, that is, either it's spin- up and carries a statistically measurable value, or spin-down and a number statistically different from the other, the difference being equal to the quantization parameter (in NMR, hbar/2; in Oil Drop, e).

Tim