Ballistic SNS sandwich as a Josephson junction

Abstract

The paper develops the theory of the ballistic SNS sandwich, in which the Josephson effect exists without the proximity effect. The analysis essentially revised the conclusions of previous works. The ballistic SNS sandwich is a π Josephson junction because its ground state corresponds not to zero Josephson phase but to the phases ±π. The analysis does not confirm previous predictions on strong suppression of the supercurrent at temperatures on the order or higher than the energy distance between Andreev levels. The disagreement is explained by violations of the charge conservation in the previous investigations. Other unusual properties of the ballistic SNS sandwich are also discussed: the absence of the Josephson plasma mode localized at the normal layer, the Meisner effect, and the Josephson vortex structure.