Josephson phase

In superconductivity, the Josephson phase is the difference of the phases of the quantum mechanical wave function in two superconducting electrodes forming a Josephson junction.

For example, if the macroscopic wave functions $\Psi_1$ and $\Psi_2$ in superconductors 1 and 2 are given by

$\Psi_1 = \sqrt{n_s} e^{i\theta_1}$
$\Psi_2 = \sqrt{n_s} e^{i\theta_2}$

then the Josephson phase is $\phi\ \stackrel{\mathrm{def}}{=}\ \theta_2-\theta_1$ .