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Science 13 August 1999:
Vol. 285. no. 5430, pp. 1036 - 1039
DOI: 10.1126/science.285.5430.1036
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Reports

Josephson Persistent-Current Qubit

J. E. Mooij, 12* T. P. Orlando, 2 L. Levitov, 3 Lin Tian, 3 Caspar H. van der Wal, 1 Seth Lloyd 4

A qubit was designed that can be fabricated with conventional electron beam lithography and is suited for integration into a large quantum computer. The qubit consists of a micrometer-sized loop with three or four Josephson junctions; the two qubit states have persistent currents of opposite direction. Quantum superpositions of these states are obtained by pulsed microwave modulation of the enclosed magnetic flux by currents in control lines. A superconducting flux transporter allows for controlled transfer between qubits of the flux that is generated by the persistent currents, leading to entanglement of qubit information.

1 Department of Applied Physics and Delft Institute for Microelectronics and Submicron Technologies, Delft University of Technology, Post Office Box 5046, 2600 GA Delft, Netherlands.
2 Department of Electrical Engineering and Computer Science,
3 Department of Physics and Center for Materials Science and Engineering,
4 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
*   To whom correspondence should be addressed. E-mail: mooij{at}qt.tn.tudelft.nl

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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J. H. Schön, C. Kloc, H. Y. Hwang, and B. Batlogg (2001)
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