JPS58209178A - Josephson integrated circuit - Google Patents

Abstract

PURPOSE:To enable to easily change the critical current ratio of the titled integrated circuit by simply altering the first and the second layers only by a method wherein, for the different logical operation of a variable threshold value characteristic type quantum interference element, an alteration is made in the aperture for Josephson junction or in the connection of a Josephson junction electrode, thereby enabling to form the greater part of construction such as inductances and electrodes in common manner. CONSTITUTION:Lower electrodes 1 and 1' constituting inductances (3/4) L and (1/4) L are provided, control electrodes 8 and 9 are formed thereon through the intermediary of an SiO insulating film, and each of said control electrodes 8 and 9 is magnetically coupled to electrodes 1 and 1' respectively. Then, an aperture is provided on the insulating film at the position as indicated by the black spot 2 in the diagram, and said aperture part is used as the Josephson junction. At this time, the critical current ratio can be set at 1:3, if the number of the black spot 2 is three on the electrode 1' side and one on the electrode 1 side, and the current ratio will be 1:1, if the number of the black spot is two on both sides. According to this constitution, an upper electrode 3 is provided, an earthing is performed through the window 4 provided on the insulating film and a terminal 5, to be used to apply a bias current, and signal current injection terminals 6 and 7 are also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to Josephson junction logic gates, and in particular to Josephson junction logic gates that have a common structure and can perform different logic operations by changing wiring connections, etc. This invention relates to logic gates and logic circuits using them.

(2) Prior art and problems The conventionally proposed variable threshold characteristic type violet interference elements have a common critical current ratio, and the logic I had chosen to create a product/disjunction. By the way, the critical current ratio at which the operating margin is maximized is different for AND and OR, so
On the other hand, the operating margin was sacrificed.

(3) Purpose of the Invention The purpose of the present invention is to have most structures such as inductance and electrodes in common, and to make it possible to easily change the critical 11 ratio by only changing 1 to 2). (4) Structure of the Invention The present invention provides a method for changing the number of openings in the insulating layer for Josephson joint formation, or changing the connection position of the Josephson junction by changing the wiring connection. According to
By changing the critical current ratio, different logic operations can be realized with the critical current ratio suitable for each, and the change is 1
This can be easily done by simply changing the photomask for one to two layers.

(5) Practical Example of the Invention FIG. 1 shows an equivalent circuit of a Doji interference element of the Machin threshold characteristic type. The critical current ratio of the two junctions J+ and Jt is 1:3
When (FIG. 1(a)), the operation margin becomes a large logical sum. IG flows through bias', and IHl and I)it are signal currents. On the other hand, the fiber product shown in Figure 1(b) is J8
．． When the critical DC ratio of J4 is 1.1, the operating margin is large. Note that the LIo product is approximately 1.4Φ0 (Φ0 is a magnetic flux quantum of 2.07 x 10-''Wb), and IH in FIG. 1(b) has an offset of Φ, /2L.

FIG. 2 is a diagram showing an embodiment of the present invention, in which 1° and 1' are lower electrodes constituting inductances T'' and τL, respectively, and a control panel insulated by an insulating layer 5iOK (not shown in the figure) on top of the lower electrodes. m[, Lr are arranged, and are magnetically coupled to 1.1' respectively. #The insulating layer V is opened with a window shown by the black dot 2 in the figure, and this part becomes a Josephson junction, but as shown in Figure 2 ( As shown in a), the number is 3 on the 1' side, 1111
If there is one in each case, the direct current ratio can be set to 1:3. On the other hand, when using two pieces at a time as shown in Figure 2 (b), the critical 'ft Mt ratio is 1:1. 3 is a lower electrode, which is applied through a window 4 opened in the Si0 layer.

5 is a terminal through which a bias current Ic flows, and 6 and 7 are signal current injection terminals.

FIG. 3 shows another embodiment. There are 2 connections on the 1' side, 1
Make one on the side and further lower ff: l'+[, pole 1, 1'
Further, on the other lower electrode 11 separated from vc i (
Create +4 junction 10. Using the above as a common structure, if 1' and 11 are connected by wiring 12 as shown in Figure 3 (&), a 31-pin junction is connected to the 1' side, and the critical DC ratio is 1' i3: becomes 1. Figure 43 (
If 1:11 is connected by wiring 13 as shown in b), a critical DC ratio of 1:1 can be obtained.

(6) Effects of the Invention According to the present invention, the variable threshold l'jjj characteristic type great characteristic type element interference element has a common structure such as cotance and electrodes.
The critical current ratio can be easily changed just by changing the photomasks of 1- to 21-, and the maximum one-crop margin can be obtained for different @embedding operations. Fig. 1 is a diagram showing an equivalent circuit of a variable threshold type key interfering element, Fig. 2 is a diagram showing the first part of the present invention, and Fig. 3
[FIG. 7] is a diagram showing another practical example of the present invention. 1 in 1
, 1' is the loop inductance of the Doji interference element, 2 is the Josephson connection, 3id upper pole, 4 is the connection part with the ground plane, and 5 is the logic voltage 1. Bias terminal for I operation, 6
．． 7 is No. 16 KK injection terminal for AND operation, 8.9
is a magnetic field coupling line for No. 1g for logical sum operation and an offset current line for logic type operation; 10 is the separated lower part r1i; Josephson junction formed on the top;
is this separated lower electrode, 12.13 is a wiring for connecting the separated lower electrode to the loose inductance 1 or 1', Jll J2-Js, J4 are Josephson junctions, each 1 3 In I.

The critical DC value of each is 21.2, where L is the loop inductance +I+ of the meter interference resistor;

IH, flows offset'.

Claims (1)

[Claims] For different logical operations of quantum interference probes with variable threshold characteristics, the Gissefson method is characterized by changing the critical current ratio by changing the opening of the Josephson junction or by changing the connection of the Josephson non-junction electrodes. Tosen circuit 1・