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Coherent Quantum Dynamics of a Superconducting Flux Qubit
I. Chiorescu,1*Y. Nakamura,12C. J. P. M. Harmans,1J. E. Mooij1
We have observed coherent time evolution between two
quantum states of a superconducting flux qubit comprising three
Josephsonjunctions in a loop. The superposition of the two states
carryingopposite macroscopic persistent currents is manipulated by
resonantmicrowave pulses. Readout by means of switching-event
measurementwith an attached superconducting quantum interference
device revealedquantum-state oscillations with high fidelity. Under
strong microwavedriving, it was possible to induce hundreds of
coherent oscillations.Pulsed operations on this first sample yielded a
relaxation timeof 900 nanoseconds and a free-induction dephasing time
of 20 nanoseconds.These results are promising for future solid-state
quantum computing.
1 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.
2 NEC Fundamental Research
Laboratories, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501, Japan.
*
To whom correspondence should be addressed. E-mail:
chiorescu{at}qt.tn.tudelft.nl
The editors suggest the following Related Resources on Science sites:
In Science Magazine
PERSPECTIVES
John Clarke (21 March 2003) Science299 (5614), 1850.
[DOI: 10.1126/science.1083001] |Summary »|Full Text »|PDF »
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