Browse Prior Art Database

Josephson Device Containing a Plurality of Microbridges

IP.com Disclosure Number: IPCOM000079578D
Original Publication Date: 1973-Jul-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Broers, AN: AUTHOR [+3]

Abstract

Josephson devices currently being investigated consist of superconductor-insulator-superconductor tunnel junctions. These devices exhibit a DC hysteresis loop and switch extremely fast. They are thus attractive for future use as memory and logic elements. Materials problems, in making the ultrathin oxide, in temperature cycling, and in the complexity of the device, continue.

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Josephson Device Containing a Plurality of Microbridges

Josephson devices currently being investigated consist of superconductor- insulator-superconductor tunnel junctions. These devices exhibit a DC hysteresis loop and switch extremely fast. They are thus attractive for future use as memory and logic elements. Materials problems, in making the ultrathin oxide, in temperature cycling, and in the complexity of the device, continue.

Josephson effects can also be observed in weak metallic links between two bulk super-conductors. The application of this type of Josephson device has been limited by at least two factors. First, these microbridges generally do not possess the energy storing capacitor of the insulator based tunnel junction, and hence by themselves do not exhibit the large hysteresis effect. Second, the study of these weak links has been limited by the poor geometric definition that has been used in the past, e.g., point contacts have been used. In spite of this difficulty, microbridges have been proposed and studied as oscillators and detectors.

An all-metal Josephson device is described using two or more microbridges which are precisely constructed, operate at microwave frequencies, and will exhibit hysteresis or at least two resistance states.

As an illustrative example, Fig. 1 shows a double bridge precisely constructed using electron-beam techniques. These bridges separately show the 0-voltage supercurrent and broad band AC effects, as shown in Fig. 2. The AC effects give rise to a DC voltage as predicted by Josephson to be 2eV(dc) = h gamma, where gamma is the frequency of the AC current. A microvolt of DC...