  We describe a quantum tunneling spectroscopy technique that requires only low
bandwidth control. The method involves coupling a probe qubit to the system
under study to create a localized probe state. The energy of the probe state is
then scanned with respect to the unperturbed energy levels of the probed
system. Incoherent tunneling transitions that flip the state of the probe qubit
occur when the energy bias of the probe is close to an eigenenergy of the
probed system. Monitoring these transitions allows the reconstruction of the
probed system eigenspectrum. We demonstrate this method on an rf SQUID flux
qubit.
