Observations of Quantum Oscillations between a Josephson Phase Qubit and a Microscopic Resonator Using Fast Readout

K.B. Cooper, Matthias Steffen, R. McDermott, R.W. Simmonds, Seongshik Oh, D.A. Hite, D.P. Pappas, and John M. Martinis,Phys. Rev. Lett. 93 , 3, 180401 (2004)

We have detected coherent quantum oscillations between Josephson phase qubits and critical-current fluctuators by implementing a new state readout technique that is an order of magnitude faster than previous methods. These results reveal a new aspect of the quantum behavior of Josephson junctions, and they demonstrate the means to measure two-qubit interactions in the time domain. The junction-fluctuator interaction also points to a possible mechanism for decoherence and reduced fidelity in superconducting qubits.