  We have detected coherent quantum oscillations between Josephson phase qubits
and microscopic critical-current fluctuators by implementing a new state
readout technique that is an order of magnitude faster than previous methods.
The period of the oscillations is consistent with the spectroscopic splittings
observed in the qubit's resonant frequency. The results point to a possible
mechanism for decoherence and reduced measurement fidelity in superconducting
qubits and demonstrate the means to measure two-qubit interactions in the time
domain.
