  In his original work Josephson predicted that a phase-dependent conductance
should be present in superconducting tunnel junctions, an effect difficult to
detect, mainly because it is hard to single it out from the usual
non-dissipative Josephson current. We propose a solution for this problem that
consists in using different superconducting materials to realize the two
junctions of a superconducting interferometer. According to the
Ambegaokar-Baratoff relation the two junctions have different conductances if
the critical currents are equal, thus the Josephson current can be suppressed
by fixing the magnetic flux in the loop at half of a flux quantum without
cancelling the phase-dependent conductance. Our proposal can be used to study
the phase-dependent conductance, an effect present in principle in all
superconducting weak links. From the standpoint of nonlinear circuit theory
such a device is in fact an ideal memristor with possible applications to
memories and neuromorphic computing in the framework of ultrafast and low
energy consumption superconducting digital circuits.
