Coherent quantum dynamics of a superconducting flux qubit.
We have observed coherent time evolution between two quantum states of a superconducting flux qubit comprising three Josephson junctions in a loop. The superposition of the two states carrying opposite macroscopic persistent currents is manipulated by resonant microwave pulses. Readout by means of switching-event measurement with an attached superconducting quantum interference device revealed quantum-state oscillations with high fidelity. Under strong microwave driving, it was possible to induce hundreds of coherent oscillations. Pulsed operations on this first sample yielded a relaxation time of 900 nanoseconds and a free-induction dephasing time of 20 nanoseconds. These results are promising for future solid-state quantum computing.
Chiorescu
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I
Quantum Transport Group, Department of NanoScience, Delft University of Technology and Delft Institute for Micro Electronics and Submicron Technology (DIMES), Lorentzweg 1, 2628 CJ Delft, Netherlands. chiorescu@qt.tn.tudelft.nl
Nakamura
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Y
Harmans
C J P M
CJ
Mooij
J E
JE