  The generation, as well as the detection, of gravitational radiation by means
of charged superfluids is considered. One example of such a "charged
superfluid" consists of a pair of Planck-mass-scale, ultracold "Millikan oil
drops," each with a single electron on its surface, in which the oil of the
drop is replaced by superfluid helium. When levitated in a magnetic trap, and
subjected to microwave-frequency electromagnetic radiation, a pair of such
"Millikan oil drops" separated by a microwave wavelength can become an
efficient quantum transducer between quadrupolar electromagnetic and
gravitational radiation. This leads to the possibility of a Hertz-like
experiment, in which the source of microwave-frequency gravitational radiation
consists of one pair of "Millikan oil drops" driven by microwaves, and the
receiver of such radiation consists of another pair of "Millikan oil drops" in
the far field driven by the gravitational radiation generated by the first
pair. The second pair then back-converts the gravitional radiation into
detectable microwaves. The enormous enhancement of the conversion efficiency
for these quantum transducers over that for electrons arises from the fact that
there exists macroscopic quantum phase coherence in these charged superfluid
systems.
