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Science 24 August 2001:
Vol. 293. no. 5534, pp. 1457 - 1459
DOI: 10.1126/science.1062266
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Reports

Time-Resolved Measurement of Dissipation-Induced Decoherence in a Josephson Junction

Siyuan Han,1* Yang Yu,1 Xi Chu,2 Shih-I Chu,2 Zhen Wang3

We determined the dissipation-induced decoherence time (DIDT) of a superconducting Josephson tunnel junction by time-resolved measurements of its escape dynamics. Double-exponential behavior of the time-dependent escape probability was observed, suggesting the occurrence of a two-level decay-tunneling process in which energy relaxation from the excited to the ground level significantly affects the escape dynamics of the system. The observation of temporal double-exponential dependence enables direct measurements of the DIDT, a property critical to the study of quantum dynamics and the realization of macroscopic quantum coherence and quantum computing. We found that the DIDT was tau d > 11 µs at T = 0.55 K, demonstrating good prospects for implementing quantum computing with Josephson devices.

1 Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA.
2 Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA.
3 Kansai Advanced Research Center, Communication Research Laboratory, Ministry of Posts and Telecommunications, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-24 Japan.
*   To whom correspondence should be addressed. E-mail: han{at}ku.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Manipulating the Quantum State of an Electrical Circuit.
D. Vion, A. Aassime, A. Cottet, P. Joyez, H. Pothier, C. Urbina, D. Esteve, and M. H. Devoret (2002)
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Coherent Temporal Oscillations of Macroscopic Quantum States in a Josephson Junction.
Y. Yu, S. Han, X. Chu, S.-I Chu, and Z. Wang (2002)
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