International Business Machines Corporation

Pierre L Gueret

Werner Baechtold

Peter Vettiger

Gerd K Binnig

Johannes Georg Bednorz

Wolfgang D Pohl

Christoph S Harder

Carl A Mueller

Heinrich Rohrer

Hans P Wolf

Hanspeter Ott

Volker Graf

Hermann E Nievergelt

Alexis Baratoff

Daniel F Widmer

A storage apparatus comprises a storage medium () on which information can be stored in form of electronic charge. The storage medium () comprises a plurality of separated electrically conductive charge-storing elements () on its surface. The apparatus further comprises a read/write head () with which the information can be written to and/or read from the storage medium (). Additionally, it contains driving means () which serves to move the read/write head () and the storage medium () relatively to each other. The read/write head () comprises cantilever means () with an electrically conductive read/write tip () which is connected to read/write means (). For writing, a charge-, voltage or current source () that delivers the electronic charge is provided. For reading, measure means () which measures the electronic charge is provided.

Storage apparatus and method utilizing a charge storage layer having discrete conductive charge-storing elements

Mechanical signal producer based on micromechanical oscillators and

The multiple STM-tip unit comprises a plurality of individually connectable, electrically separated tunnel tips (52 . . . 54) arranged in a common sandwiched block (5), in the form of a plurality of electrically conducting layers (41, 46, 50) each associated with at least one of said tunnel tips (52 . . . 54) with insulating layers (44, 48) intercalated between said conducting layers (41, 46, 50), the latter each having a contact pad (36, 42, 43) for connection to appertaining electronics. The thickness, area, and material characteristics of said insulating layers (44, 48) are chosen such that the tunnel current through any one of the intercalated insulating layers (44, 48) is negligible with respect to the tunnel current flowing across the gap between the involved tunnel tips (52 . . . 54) and the surface with which said tips cooperate.

Multiple-tip scanning tunneling microscopy

The transistor comprises two electrodes, (source (22) and drain (23), with a semiconductor tunnel channel (21A, 21B) arranged therebetween. A gate (24) for applying control signals is coupled to the channel. The semiconductor channel consists of a plurality of regions differing in their current transfer characteristics: contact regions (21c), connected to the source and drain electrodes, and a tunneling region (21t) arranged between the contact regions. The energy of free carriers in the contact regions differs from the energy of the conduction band or the valence band of the tunneling region which forms a low energy tunnel barrier the height (.DELTA.E) of which can be modified by control signals applied to the gate. The operating temperature of the device is kept sufficiently low to have the tunnel current through the barrier outweigh currents of thermionically excited carriers.

Low temperature tunneling transistor

The transistor comprises two electrodes, source (12) and drain (13), with a semiconductor tunnel channel (11) arranged therebetween. A gate (14) for applying control signals is coupled to the channel. The semiconductor, at low temperatures, behaves like an insulator with a low barrier (some meV) through which charge carriers can tunnel under the influence of an applied drain voltage. The tunnel current can be controlled by a gate voltage V.sub.G which modifies the barrier height between source and drain thereby changing the tunnel probability.

A vacuum transfer device includes a central processing chamber and a plurality of additional chambers radially positioned around the central chamber and in vacuum-tight connection therewith. A rotatable coulisse arrangement in the central chamber is extendable so as to reach into the additional chambers when correctly aligned. The device can transfer objects among several work stations without intermediate venting and re-evacuation of the system of chambers.

Vacuum transfer device

For storing digital data e.g. in magnetic vortex shift registers, a single flux quantum vortex is injected into a superconductive layer by a vortex generator consisting of an emitter and a transfer station. The emitter generates a pool of vortices. The transfer station upon a signal transfers one single vortex at the time. In a particular embodiment, the transfer station consists of a Josephson interferometer at the entrance of a transfer channel. Switching of the interferometer passes a flux vortex from a vortex pool to a shifting and storage apparatus. Other embodiments do not use interferometers but include transfer channels with separation corners and vortex spacing means which insure that upon application of appropriate signals one and only one vortex is passed from the vortex pool to the shifting and storage means.

Magnetic vortex generator with a vortex pool and single vortex transfer

Logic elements comprising resettable Josephson junctions cooperating with matched transmission lines have input circuit inductances connected to reversible Josephson devices which are so small that a flux of less than one flux quantum only can be trapped therein preventing the continued circulation of supercurrent in the inductance after removal of the input signals from the associated reversible Josephson junctions. The resettable junctions are designed such that upon removal of the input or control field from the resettable Josephson junctions connected to the transmission line, the a.c. voltage which is generated across said junction, is larger than the time-average d.c. voltage across said junction when switched to its state of normal conductance so that, after removal of the input or control field from said junction, the d.c. voltage is caused to lock back to zero, thus resetting the element. Circuit parameters for achieving resettability without interrupting gate current are given. Logic circuits including AND, OR and NOT circuits are described and the conditions for the operation of such circuits which include both resettable and reversible Josephson devices are also given.

Josephson junction logic element

Two Josephson gates are connected in series to a low impedance voltage source. Each junction is bridged by a load impedance. The feed voltage is maintained in the order of the gap voltage which corresponds to the voltage drop across a Josephson junction when it is in its single-particle-tunneling state. Therefore, only one out of both Josephson elements can exist in the voltage state at a time, and the other junction is forced to assume the superconducting pair-tunneling state. In its symmetric form, the basic circuit can be used as flip-flop or storage means. If asymmetric, the basic circuit shows monostable switching behavior, and it can be used as logic gate. Circuit asymmetry can be caused either by design using different junction areas or electrically by proper bias control currents applied to either or both gates of the basic circuit. The degree of symmetry or asymmetry can even be shifted with electrical means. AND and OR gates and inverting embodiments which perform logic NAND and NOR functions are shown.

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Richterswil, Switzerland

Pierre L Gueret