  Most materials freeze when cooled to sufficiently low temperature. We find
that magnetic dipoles randomly distributed in a solid matrix condense into a
spin liquid with spectral properties on cooling that are the diametric opposite
of those for conventional glasses. Measurements of the non-linear magnetic
dynamics in the low temperature liquid reveal the presence of coherent spin
oscillations composed of hundreds of spins with lifetimes up to ten seconds.
These excitations can be labeled by frequency, manipulated by the magnetic
fields from a loop of wire, and permit the encoding of information at multiple
frequencies simultaneously.
