DOI: 10.1209/epl/i2001-00277-9


Europhys. Lett., 54 (4) , pp. 515-521 (2001)

Observation of nonequilibrium libration states in a single-junction superconducting quantum interferometer

E. Il'ichev¹, M. V. Fistul², B. A. Malomed³, H. E. Hoenig¹ and H.-G. Meyer<sup>1

1</sup>  Institute for Physical High Technology, Department of Cryoelectronics D-07702 Jena, Germany
²  Max-Planck Institut für Physik Komplexer Systeme - D-01187 Dresden, Germany
³  Department of Interdisciplinary Studies, Faculty of Engineering Tel Aviv University - Tel Aviv 59978, Israel

(Received 21 December 2000; accepted in final form 8 March 2001)

Abstract
We report an experimental and theoretical study of various metastable states of a superconducting loop including a Josephson junction (a single-junction superconducting quantum interferometer). In the experiment, the metastable states manifest themselves by sharp drops in the magnetic-field dependence of the interferometer's response to an externally applied weak alternating bias current. At low temperatures we also observe satellite drops that appear at small values of ac bias. By making use of a mapping to the theory of nonlinear oscillator, we argue that this feature is due to the presence of nonequilibrium ac-induced libration states of the interferometer.

PACS
74.50.+r - Proximity effects, weak links, tunneling phenomena, and Josephson effects.
05.45.-a - Nonlinear dynamics and nonlinear dynamical system.


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