Junctions ‐ types, properties, and limitations

The types of Josephson junctions are surveyed, with emphasis on tunnel and constriction configurations as limiting examples. The limits on the intrinsic high‐frequency performance set by capacitive and heating effects are analyzed theoretically, and the latter compared with experimental data on VTB’s and point contacts. Nonequilibrium effects more subtle than those accounted for by simple heating are briefly considered. Finally, the properties of point contacts which apparently show nearly ideal intrinsic frequency‐dependent behavior out to far infared frequencies of twice the gap frequency are summarized.