Josephson device threshold gates

Claim 1

A threshold logic gate of the type having n inputs, weighting means for each of said inputs, summing means and threshold means, the improvement comprising: a. a plurality of series connected Josephson devices of the type which have zero voltage there-across when the current therethrough is below a critical current and a finite welldefined voltage, Delta , there-across, when the current equals or exceeds the critical current, b. input control lines each associated with specific ones of said series connected Josephson devices and positioned to provide a magnetic field to change the critical current of said specific ones of said devices, c. means for applying a gating current to said series connected Josephson devices, said gating current having a Josephson between the critical current values which would be established by first and second current values applies to any of said input control lines, wherein each said input control line is adapted to carry a logic 0 current of value Ic and a logic 1 current of value Ic , where Ic NOT = Ic , and wherein said currents Ic and Ic cause the specific Josephson devices associated with said control lines to have critical currents of Im and Im , respectively, Im NOT = Im , and wherein said gating current applied to said series connected Josephson devices has a value I1 which is less than Im and equal to or greater than Im , wherein the voltage across said series connected Josephson devices equals m Delta , where Delta is the voltage across an individual Josephson device which has been switched from V 0 to V NOT = 0, and where m is the number of said series connected Josephson devices associated with input control lines carrying currents of value Ic , d. a resistance, R, connected in a current path in parallel with said series connected devices, e. a further Josephson device positioned to be influenced by the magnetic field caused by current flowing in said parallel current path, f. means for applying a gating current to said further Josephson device whereby the switching of said further Josephson device from a zero voltage depends upon the current value in said alternate path, and g. means electromagnetically coupled to said further Josephson device for varying the threshold of said threshold logic gate and thereby altering the logic function carried out by said threshold logic gate.