Superconducting memory array using weak links

Claim 2

A superconducting memory, comprising: a plurality of superconducting loops, each one of which has at least one element therein capable of supporting a Josephson current therethrough, said loops being capable of trapping magnetic flux quanta therein as representations of a data information state, each loop being characterized by inductance L, capacitance C, and damping R where 3/4 phi 0 < OR = LI0 < OR = 7/4 phi 0 , anD (1/R2) - 4C/L) > OR = 0 where phi 0 is a magnetic flux quantum equal to 2.07 X 10 15 webers and I0 is the maximum Josephson current which the loop can sustain; information producing means for generating a single flux quantum in selected loops, said flux quantum being indicative of said information state; selection means connected to said information producing means for selecting which superconducting loops are linked by said magnetic flux, said selection being in accordance with a predetermined data format.

Claim 3

The memory of claim 1, where said generating means comprises coincidentally driven lines located near each said superconducting loop, and current sources for providing currents in said lines, the total current in said lines near each said loop being sufficient to cause linking of one flux quantum in said loop.

Claim 4

The memory of claim 2, where said drive lines are arranged in X-Y coordinate fashion, said X lines and said Y lines producing magnetic flux which links each superconducting loop in the same direction.

Claim 5

The memory of claim 2, further comprising sense lines for detecting the magnetic flux trapped in said superconducting loops, said sense lines being comprised of said coincidentally driven lines.

Claim 6

The memory of claim 2, further comprising sense lines for detecting the magnetic flux trapped in said superconducting loops, said sense lines being located near each said superconducting loop.

Claim 7

The memory of claim 2, wherein each said drive line is connected to a current source for providing current in each said line, and each said loop has a plurality of drive lines thereacross, the total current in said plurality of drive lines across each superconducting loop being sufficient to induce a current in each loop of a magnitude which is greater than the maximum Josephson current of the Josephson device of each loop.

Claim 8

The memory of claim 2, where said selection means comprises at least one address unit and decoders connected to said drive lines, said address unit and said decoders connecting said current sources to selected drive lines.

Claim 9

The memory of claim 1, where said superconducting loops are located on a superconducting ground plane, each loop having a thin film, planar Josephson device therein.

Claim 10

The memory of claim 1, where said superconducting loops are located on a superconducting ground plane, each loop having a constriction-type weak link Josephson device therein.

Claim 11

A superconducting memory array, comprising: a plurality of superconducting memory cells located on a superconducting ground plane, each of said cells comprising a ring of superconducting material having at least one superconducting weak link therein, said weak link being capable of supporting Josephson current therethrough, each said cell being characterized by an inductance L, capacitance C, and damping R, where 3/4 phi 0 < or = LI0 < or = 7/4 phi 0 , and (1/R2) - (4C/L) > or = 0 where phi 0 is a flux quantum defined as 2.07 X 10 15 webers and I0 is the maximum Josephson current which the loop can sustain; generating means located near said cells for producing magnetic flux which threads each said cell, said generating means producing sufficient flux to trap a single flux quantum in said cell, and to cause expulsion of said trapped flux; selection means connected to said generating means for selecting which of said memory cells is to be threaded by said magnetic flux; sensing means for detecting the presence of trapped flux in each said memory cell, said sensing means being responsive to said selection means for sensing the flux trapped in selected memory cells, wherein said generating means comprises a group of drive lines for each memory cell, each drive line being connected to a current source for producing Drive currents in said lines, wherein the total current in each said group of drive lines is sufficient to cause trapping of a flux quantum in said memory cells.

Claim 12

A superconducting memory array, comprising: a plurality of superconducting memory cells located on a superconducting ground plane, each of said cells comprising a ring of superconducting material having at least one superconducting weak link therein, said weak link being capable of supporting Josephson current therethrough, each said cell being characterized by an inductance L, capacitance C, and damping R, where 3/4 phi 0 < or = LI0 < or = 7/4 phi 0 , and (1/R2) - (4C/L) > or = 0 where phi 0 is a flux quantum defined as 2.07 X 10 15 webers and I0 is the maximum Josephson current which the loop can sustain; generating means located near said cells for producing magnetic flux which threads each said cell, said generating means producing sufficient flux to trap a single flux quantum in said cell, and to cause expulsion of said trapped flux; selection means connected to said generating means for selecting which of said memory cells is to be threaded by said magnetic flux; sensing means for detecting the presence of trapped flux in each said memory cell, said sensing means being responsive to said selection means for sensing the flux trapped in selected memory cells, wherein said generating means comprises a group of drive lines for each memory cell, each drive line being connected to a current source for producing Drive currents in said lines, wherein the total current in each said group of drive lines is sufficient to cause trapping of a flux quantum in said memory cells.

Claim 13

The memory of claim 10, wherein said selection means comprises address means and decoder means connected to said current sources for selectively biasing said drive lines.

Claim 14

The memory of claim 11, wherein said drive lines are arranged in coordinate fashion across said array and are coincidentally biased by said selection means and said generating means, each said group of drive lines being located on one side of the associated memory cell.

Claim 15

A superconducting memory, comprising: a superconducting ground plane; a plurality of discrete insulating layers located on said ground plane, said layers extending in a first direction across said ground plane; a plurality of discrete superconducting film strips on each said insulating layer, said film strips extending in a second direction and contacting said superconducting ground plane in at least one location; Josephson current devices, there being at least one of said devices in each superconducting film strip; thin film superconducting drive lines located over each said film strip and insulated therefrom; current sources connected to said drive lines for generating current pulses in said drive lines; selection means connected to said current sources for selectively connecting said current sources to said drive lines.

Claim 16

A superconducting memory, comprising: a superconducting ground plane; a plurality of discrete insulating layers located on said ground plane, said layers extending in a first direction across said ground plane; a plurality of discrete superconducting film strips on each said insulating layer, said film strips extending in a second direction and contacting said superconducting ground plane in at least one location; Josephson current devices, there being at least one of said devices in each superconducting film strip; thin film superconducting drive lines located over each said film strip and insulated therefrom; current sources connected to said drive lines for generating current pulses in said drive lines; selection means connected to said current sources for selectively connecting said current sources to said drive lines.

Claim 17

The memory of claim 13, wherein said drive lines are arranged in coordinate fashion, there being a plurality of said drive lines located over each said film strip.

Claim 18

The memory array of claim 13, wherein said current sources and drive lines produce magnetic flux in said insulating layers in the vicinity of said film strips, the amount of magnetic flux produced by said current sources and said drive lines being approximately a single flux quantum of 2.07 X 10 15 webers.

Claim 19

The memory of claim 13, wherein each said discrete film strip forms a superconducting loop with said ground plane, said loops being characterized by a capacitance C, inductance L, and damping R given by 3/4 phi 0 < or = LI0 < or = 7/4 phi 0 , and (1/R2) - (4C/L) > or = 0 where phi 0 is a flux quantum of 2.07 X 10 15 webers.

Claim 20

The memory array of claim 13, where each said Josephson device is a thin film junction device having a tunnel barrier located between said ground plane and each of said film strips.

Claim 21

The memory array of claim 13, wherein said Josephson devices are constriction-type devices formed in said film strips, each said constriction device being characterized by a region in said strip having less width than the surrounding strip.

Claim 22

A superconducting memory, comprising: a superconducting ground plane; a first layer of spaced insulating strips extending across said plane in a first direction; a layer of spaced superconducting strips having Josephson current devices therein, said superconducting strips being deposited on said insulating strips, said superconducting strips extending in a second direction; a second layer of insulation located over each said superconducting strip; a first layer of superconducting drive lines located over each said superconducting strip, the current flow in said drive lines producing magnetic flux which threads the volume between said superconducting strips and said ground plane; a third layer of insulation deposited on said drive lines; a second layer of superconducting drive lines located over each said superconducting strip, the current flow in said second layer drive lines producing magnetic flux which threads the volume between said superconducting strips and said ground plane; current sources connected to said fourth layer of drive lines and to said second layer of drive lines for producing current in said second layer of drive lines; selection means connected to said current sources for coincidentally connecting groups of said drive lines of said current sources; sensing means for detecting the magnetic flux which threads each said volume between said superconducting strips and said ground plane.

Claim 23

A superconducting memory, comprising: a superconducting ground plane; a first layer of spaced insulating strips extending across said plane in a first direction; a layer of spaced superconducting strips having Josephson current devices therein, said superconducting strips being deposited on said insulating strips, said superconducting strips extending in a second direction; a second layer of insulation located over each said superconducting strip; a first layer of superconducting drive lines located over each said superconducting strip, the current flow in said drive lines producing magnetic flux which threads the volume between said superconducting strips and said ground plane; a third layer of insulation deposited on said drive lines; a second layer of superconducting drive lines located over each said superconducting strip, the current flow in said second layer drive lines producing magnetic flux which threads the volume between said superconducting strips and said ground plane; current sources connected to said fourth layer of drive lines and to said second layer of drive lines for producing current in said second layer of drive lines; selection means connected to said current sources for coincidentally connecting groups of said drive lines of said current sources; sensing means for detecting the magnetic flux which threads each said volume between said superconducting strips and said ground plane.

Claim 24

The memory of claim 19, wherein each superconducting strip forms a memory loop with said ground plane, each said memory loop having an insulating strip therein and being characterized by inductance L, capacitance C, and damping R given by 3/4 phi 0 < or = LI0 < or = 7/4 phi 0 , and (1/R2) - (4C/L) > or = 0 where phi 0 is a flux quantum equal to 2.07 X 10 15 webers.

Claim 25

The memory of claim 19, wherein said first layer of drive lines extends in a direction transverse to said second layer of drive lines.

Claim 26

A superconducting memory, comprising: a superconducting ground plane; a plurality of memory cells located over said ground plane, each said memory cell comprising: a layer of insulating material formed on said ground plane and a strip of superconducting material located over said insulating material, said superconducting strip and said ground plane forming a loop having said insulating material therein; a superconducting weak link capable of supporting Josephson current therethrough; magnetic flux generating means for linking flux in each said loop, said generating means comprising superconducting drive lines insulated from said memory cells and electrical sources connected to said drive lines for producing current pulses therein; selection means for selectively connecting said current sources to said drive lines; sensing means for detecting the amount of flux which links each said loop.

Claim 27

A superconducting memory, comprising: a superconducting ground plane; a plurality of memory cells located over said ground plane, each said memory cell comprising: a layer of insulating material formed on said ground plane and a strip of superconducting material located over said insulating material, said superconducting strip and said ground plane forming a loop having said insulating material therein; a superconducting weak link capable of supporting Josephson current therethrough; magnetic flux generating means for linking flux in each said loop, said generating means comprising superconducting drive lines insulated from said memory cells and electrical sources connected to said drive lines for producing current pulses therein; selection means for selectively connecting said current sources to said drive lines; sensing means for detecting the amount of flux which links each said loop.

Claim 28

The memory of claim 22, wherein each Josephson device is a planar device having an electron tunnel barrier formed between said ground plane and each superconducting strip.

Claim 29

The memory array of claim 22, wherein each Josephson device is a constriction-type device formed in each superconducting strip.

Claim 30

The memory of claim 22, wherein each loop has inductance L, capacitance C, and damping R characterized by 3/4 phi 0 < or = LI0 < or = 7/4 phi 0 , and (1/R2) - (4C/L) > or = 0 where phi 0 is a flux quantum equal to 2.07 X 10 15 weber.

Claim 31

The memory of claim 22, where said drive lines are arranged in X and Y coordinate fashion, there being an X line and a Y line located in flux linking relationship to each said loop, the sum of currents in each flux-linked group of X and Y conductors being sufficient to produce a linking flux quantum in each said loop.