= Fraunhofer pattern of a Josephson junction
{c}
{title2=$I_c(\Phi)=I_c(0)|\sin(\pi\Phi/\Phi_0)/(\pi\Phi/\Phi_0)|$}
A spatially uniform <Josephson junction> in a uniform transverse in-plane <magnetic field> has a linear gauge-invariant phase profile across its width. Integrating its sinusoidal local <current-phase relation of a superconducting weak link> gives a signed sinc coefficient multiplying the sine of the central phase. Maximizing over that phase gives the displayed nonnegative critical-current envelope. Zeros occur at nonzero integer multiples of the <superconducting flux quantum>. The relevant magnetic thickness includes electrode penetration when appreciable, and self-fields or nonuniform local critical current density alter the simple pattern.
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