Quantum decay of metastable current states at superconducting junctions

A. Barone, Roberto Cristiano

Joseph Lambert, Steven A. Carabello, Zechariah Thrailkill +1 more

Evgeni V. Il’ichev, M. V. Fistul, Boris A. Malomed +2 more

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.

Qing Hu, C. A. Mears, P. L. Richards +1 more

Yoshimasa Murayama, A. Asano, Nobuo Kotera

Switching dynamics have been considered for a simple closed loop composed of a Josephson junction and inductors (an ac superconducting quantum interference device). The rest current which remains in the junction after self-resetting was calculated by either (1) assuming that the junction closes instantaneously after its current is reduced to below Imin, or (2) by means of simulation for t→∞. It is shown from a free energy viewpoint that the introduction of flux quanta is favorable. However, the final state is not the absolute minimum energy, but a metastable state.

T. Claeson, Floriana Lombardi, Thilo Bauch +5 more