Josephson junction with two superconducting current components

The properties of a Josephson junction with the 2π- and 4π-periodic superconducting current component have been analyzed. In the range of low voltages, such a junction exhibits the 4π periodicity of the phase difference for the Majorana current amplitude much smaller than the Josephson current, which makes it possible to observe Josephson current oscillations with a fractional period for small dissipation β < 1 in the hysteresis region. The effect the 4π-periodic Majorana current component is also manifested in a change in the sequence of steps in the ladder structure emerging on the current–voltage ( I–V ) characteristic of the junction. We have determined the interval of external electromagnetic radiation amplitudes, in which the manifestation of the fractional Josephson effect on the I–V characteristic is most significant.