Theory of the nonreciprocal Josephson effect
Kou Misaki, Naoto Nagaosa
Abstract
The heterojunction between different materials often exhibits a rectifying effect; e.g., pn junction is used for diode. On the other hand, the Josephson junction between two different superconductors is assumed to show symmetric response between two directions of the current, i.e., the voltage drop $V$ is antisymmetric with respect to the sign change of the current $I$. However, there should be an asymmetry between the states of charge accumulation on the right and left sides of the Josephson junction, which can lead to the nonreciprocal responses. Here we demonstrate theoretically that nonreciprocal $I\text{\ensuremath{-}}V$ characteristic appears due to this charging energy difference both in the classical and quantum regimes.