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A shift register is described which employs as information bits the flux quantum vortices occurring in Josephson junctions of extended dimensions. The positions of the vortices can be controlled and manipulated by an appropriately designed circuit geometry and by application of currents and magnetic fields. The time required for switching of the position of a vortex can approach the period of the Josephson plasma oscillation (∼10 ps) and the intrinsic energy dissipation is typically ≲ 10-18J/shift.

The dynamics of flux entry into a superconducting loop interrupted by a thin-film Josephson junction have been studied experimentally. A computer simulation of the system yields excellent agreement with these data. It is found that a specific number of flux quanta will bubble into a loop, and that this number depends only on the relative damping which is present.

We have made what we believe is the first experimental observation of the switching transients resulting from single flux quantum transitions in superconducting devices. For that purpose, we used ``long'' Josephson junctions or interferometers which exhibit overlapping vortex modes. By applying a magnetic field to such devices, vortex‐mode transitions are induced. The resulting transients are detected by a small Josephson junction located nearby. The experimental results show unambiguously that the points where a signal is detected by the sense junction correspond to the vortex‐mode boundaries of the device. These results have important implications for memory applications.

Operation of a DRO single flux quantum Josephson junction memory cell is described. Writing and sensing is performed with coincident currents. The device acts as its own sense detector, switching to the gap voltage if a flux quantum was stored. Dense arrays not requiring standby power are potentially feasible.

A quantum interference Josephson junction logic device is disclosed which comprises three or more junctions connected in parallel which are capable of carrying Josephson current and includes means integral with at least one of the junctions for carrying a larger maximum Josephson current than the remaining junctions. This integral means includes means for carrying a maximum Josephson current which is twice as large as the maximum Josephson current in the remaining junctions. While the spacing between the lobes of the threshold curve (Im vs. Ic) is increased over that of a two junction interferometer by adding another junction resulting in an increased operating region in which logic circuits switch to the voltage state, good current gains with large lobe separation could not be achieved by the mere addition of junctions. Current gain with large lobe separation is obtained if the two outer junctions having a zero field threshold current, Io, are connected via an inductance, L, to the center junction with a maximum Josephson current, 2Io. The gain is maximized if the gate current, Ig, is fed into the device through inductances, Lp, having a value of inductance approximately equal to 3L in the center of inductances L which are disposed between pairs of junctions forming a symmetrical dual feed. Increased gain and operating range can be achieved using the symmetrical dual feed and interferometer arrangements where the maximum Josephson current in all the junctions thereof is the same.

Under the proper circumstances voltage can be developed across a superconductor‐this voltage V is the electromotive force induced by flux flow through the superconducting material. Superconducting thin‐film techniques have been developed to assure that this flow is composed of individual flux quanta. These techniques usually involve inhomogeneous superconductivity; the inhomogenity either being artificially generated by flow through a constriction (as a Dayem bridge) or intrinsic to the material itself (as a deliberate spacial modification of electron density, Notarys). This resulting superconducting structure may be thought of as a current controlled flux valve‐passing quanta φ0 at a rate v=Vφ0−1. These flux valves have been incorporated into various circuits leading to results similar to the behavior of a Josephson Junction. In particular, inserting a valve into a superconducting ring produces a device similar to the Josephson Junction interferometer‐highly sensitive to magnetic field. These devices hav...