  A magnetically levitated mass couples to gravity and can act as an effective
gravitational wave detector. We show that a superconducting sphere levitated in
a quadrupolar magnetic field, when excited by a gravitational wave, will
produce magnetic field fluctuations that can be read out using a flux tunable
microwave resonator. With a readout operating at the standard quantum limit,
such a system could achieve broadband strain noise sensitivity of $h \lesssim
10^{-19}/\sqrt{\rm Hz}$ for frequencies of $10~\mathrm{kHz}~-~1~\mathrm{MHz}$,
opening new corridors for astrophysical probes of new physics.
