2012/07/12 by H. Sickinger, A. Lipman, M. Weides +5 · 1 citation
Physics and Astronomy · #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevlett.109.107002
published as Phys. Rev. Lett. 109, 107002 (2012)
arxiv created 2012/07/12 · arxiv updated 2012/09/10
We demonstrate experimentally the existence of Josephson junctions having a doubly degenerate ground state with an average Josephson phase ψ=±ϕ. The value of ϕ can be chosen by design in the interval 0<ϕ<π. The junctions used in our experiments are fabricated as 0-π Josephson junctions of moderate normalized length with asymmetric 0 and π regions. We show that (a) these ϕ Josephson junctions have two critical currents, corresponding to the escape of the phase ψ from -ϕ and +ϕ states; (b) the phase ψ can be set to a particular state by tuning an external magnetic field or (c) by using a proper bias current sweep sequence. The experimental observations are in agreement with previous theoretical predictions.