Fig. 3: Josephson 0-π transition.

a Critical supercurrent density I_cL/W (I_c is in units of 4eλ₁λ₂/π²ℏ) as a function of μ for φ = 0 and L = 20. The dashed curve is the plot of Eq. (9) with the same parameters. I_c oscillates around 0 as L increases. The light green shadows represent the π-junction regions as indicated. b Current-phase relation for μ = 0.2, 0.4 and 0.6, respectively [marked by the colored stars in (a)]. c I_c/W as a function of junction length L for φ = 0 and π/4, respectively. We take μ = 1 for illustration. The dashed curves are the plots of Eq. (9) for φ = 0 and π/4, respectively. d Current-phase relation for L = 2.5, 5, and 8, respectively [marked by the colored stars in (c)]. e I_cL/W as a function of φ for μ = 1 and L = 25. The dashed curve is the plot of Eq. (9) with the same parameters. The light green shadows represent the π-junction regions. f Current-phase relation for φ = 0, 0.1π and 0.25π, respectively [marked by the colored stars in (e)]. Other parameters are the same as Fig. 2 for all plots.