JPH01201973A - Magnetic flux quantum logic element and asynchronous counter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic flux quantum logic device that controls the propagation of magnetic flux quanta (called Josephson hortesox) in a Josephson line by other magnetic flux quanta. It relates to magnetic flux quantum logic elements used in high-speed logic circuits, memories, etc.

[Prior art] Conventionally, to construct a T flip-flop using a superconductor,
As shown in FIG. 11, magnetically coupled Josephson junction 4
TD-furi is constructed using two.

Pflosop (see Japanese Patent Application No. 57-174926) has a configuration in which circuit A2 is connected to the next stage of A1 without a combinatorial output terminal, and terminals 1 and 3 from which the Q signal is output are connected to terminal T2. This requires a very complicated circuit configuration, and because of this complicated circuit configuration, the margin is narrow and high-speed operation cannot be achieved. Furthermore, the 11th
In the figure, Ti and T4 are terminals.

[Invention or problem to be solved]

Therefore, the problem to be solved by the present invention is to configure a flip-flop with a simpler circuit configuration than that of the prior art. This should be done every time high-speed operation is achieved.

[Means for solving problems]

In order to solve such problems, the present invention has developed
A Josephson junction is sandwiched between an upper electrode and a lower electrode consisting of a body, and has a long structure in only one direction, with one end being the input end and the other end being the output end. The first to third Josephson lines are provided, and between the output end of the first Josephson line and the input end of the second Josephson line, and between the output end of the first Josephson line and the third Josephson line.
Either connect both the upper and lower electrodes to the input end of the Josephson line with a resistor, or connect one of the upper electrodes and the lower electrodes with a resistor and connect the external force with a superconductor. , the input end of the second Josephson line and the input end of the third Josephson line are connected by superconductors for both the upper electrodes and the lower electrodes, respectively. This allows magnetic flux quanta to be held in a superconducting loop composed of a Josephson line and a superconductor.

[Effect]

The magnetic flux quantum logic device according to the present invention has the characteristic that the magnetic flux quanta propagating in the Josephson line self-shapes during propagation even if the waveform once collapses. The next stage input is always kept constant,
It is possible to prevent a decrease in margin due to multi-stage connection.

〔Example〕

Examples of the present invention will be described below using 17 screens.

The embodiment of the present invention is constructed using at least first to third Josephson lines. First, here, the substrate is constructed with a laminated structure in which a tunnel barrier is sandwiched between an upper electrode and a lower electrode made of a superconductor, and such a laminated structure has a Josephson penetration distance in the propagation direction of magnetic flux quanta. A description will be given using a distributed constant type line having a length of about five times λJ or more.

FIG. 1 shows an explanatory diagram of the first embodiment. In the figure, 1 is the first
Josephson line, 2 is the second Josephson line, 3
is the third Josephson line, 4 is a resistor, 5 is an inductance, 6 is a superconductor, 7 is a tunnel barrier, T1 is an input end, T2 . T3 is an output end. The output end of the first Josephson line 1 and the input end of the second Josephson line 2 and the output end of the first Josephson line 1 and the input end of the third Josephson line 3 are independent from each other. is connected to by a resistor 4. Furthermore, since the input end of the second Josephson line 2 and the input end of the third Josephson line 3 are connected through the inductance 5, the junction of the second Josephson line 2 - the interface 5 - A superconducting loop consisting of a path between the junction of the third Josephson line 3 and the ground plane is formed. Here, the size LI product of this superconducting loop (L: value of inductance composing the superconducting loop, ■ = critical current value of the Josephson junction included in the superconducting loop) is the shaded area in Figure 2. S
Set so that condition a is satisfied. Under the conditions of the region Sa, magnetic flux quanta that have entered the Josephson line 2 are stopped and held in the superconducting loop. Magnetic flux quanta do not stop in region sb.

In the above structure, the auxiliary bias current 1 is supplied only to the input end of the second Josephson line 2, and the magnetic flux quantum that has propagated through the first Josephson line 1 is transferred to the second Josephson line 2 through the resistor 4. The signal propagates through the third Josephson line 3, but is set so as not to propagate to the third Josephson line 3.

In this state, when a magnetic flux quantum is propagated from the first Josephson line 1, the magnetic flux quantum enters the second Josephson line 2, and one end of the magnetic flux quantum is transferred to the second Josephson line 2. It propagates to the output end T2, and the other end is held in a superconducting loop constructed between the second Josephson line 2 and the third Josephson line 3. At this time,
During the superconducting loop, a circulating current associated with magnetic flux quanta flows from the lower electrode to the upper electrode at the input end of the second Josephson line 2, and from a portion of the electrode to the lower electrode at the input end of the third Josephson line 3. Flows in the direction of the electrode. Therefore, at the input end of the second Josephson line 2, the auxiliary bias current 1 and the circulating current associated with the magnetic flux quantum cancel each other out, and at the input end of the third Josephson line 3, the auxiliary bias current 1 is supplied. It has the same effect as . In this state, when the next magnetic flux quantum is propagated from the first Josephson line 1, the magnetic flux quantum enters the Josephson line 3, propagates to the output Oi#i of the Josephson line 3, and at the same time, inside the superconducting loop. An annihilation occurs with the retained magnetic flux quantum, returning to the initial state.

Therefore, the magnetic flux quantum propagated from the first Josephson line 1 is transmitted to the output end T2 of the second Josephson line 2 and the third
The signal is alternately propagated to the output end T3 of the Josephson line 3, and a T flip-flop can be realized.

In order to confirm the above-mentioned cycle-dividing operation in this structure, a simulation was performed using a circuit analysis program.

Third, the value Rcp of the resistor 4 that connects the first line 1, the second line 2, and the third line 3, and the magnetic flux quantum that connects the second line 2 and the third line 3 are determined. The results of examining the operating margin using the inductance (correction CP) that constitutes the stop section as a parameter are shown. Operating region S2 in which the flux propagates to the line, △ indicates operating region S3 in which the flux does not propagate to either line 2 or line 3, × indicates that the magnetic flux quantum is retained in the magnetic flux quantum stop part, but the magnetic flux quantum is not propagated in the line 3. An operating region S4 in which no propagation occurs is shown.From this result, it can be seen that there is an operating margin of about ±30% for the connection resistance RCP and about ±30% for the connection inductance .

In addition, in FIG. 3, the line bias condition IB/
I J-0,4, auxiliary bias current 1++'-0,45
It is mA.

A lumped constant type Josephson line can also be applied to the Josephson line in the above embodiments, as well as the above-mentioned distributed constant type Josephson line.

Here, a lumped parameter Josephson line is defined as a first layered structure having a layered structure similar to a distributed type Josephson line, and in addition to this first layered structure, an upper layer made of a superconductor. A second laminated structure portion is provided between the electrode and the lower electrode, in which an insulating layer having a thickness such that the I-N-F'1E current cannot flow is sandwiched between the electrode and the lower electrode.

The first laminated structure portion and the second laminated structure portion are alternately connected, and the length of the first laminated structure portion is formed to be smaller than the Josephson penetration distance λ.

FIG. 4 is an explanatory diagram showing a second embodiment of the present invention, and compared to FIG. 1, a resistor 4a is added, and this resistor 4a causes the Josephson line l and the Josephson line 2 And the Josephson line 1 and the Josephson line 3 are connected to each other by the lower electrodes. This embodiment also operates in the same way as the first embodiment.

FIG. 5 is an explanatory diagram showing a third embodiment of the present invention. Compared to FIG. A Son line 1 and a Josephson line 3 are connected to each other through their lower electrodes. This embodiment also operates in the same way as the first embodiment. In the third embodiment, the upper electrodes are connected to each other by the resistor 4, and the lower electrodes are connected to each other by the inductance 4b, but conversely, the lower electrodes are connected to each other by the resistor 4, and the upper electrodes are connected to each other by the inductance 4b. The same operation can be performed even if they are connected together through an inductance 4b.

FIG. 6 is an explanatory diagram showing a fourth embodiment of the present invention, and compared to FIG. 1, Josephson junctions 1a to 1d and 2a to 2d have four Josephson lines.

The difference is that it is composed of 3a to 3d. In each Josephson junction, part of the electrodes and the lower electrodes are connected to each other by an interface 8. This example also applies to the first
The same operation as in the embodiment is performed.

A fifth embodiment of the present invention is shown in FIG. 7(a), tb+.

In FIG. 7(a), 11 is a first Josephson line, 12 is a second Josephson line, 13 is a third Josephson line, 14 is a fourth Josephson line, 15 is a resistor, and 16 is a third Josephson line. is an interface, T11, T13 are input terminals, T12 . 'r14 is an output terminal. The output end of the first Josephson line 11, the input end of the second Josephson line 12, the output end of the third Josephson line 13, and the fourth
Input of Josephson line 14*:1. ; are each independently connected to a resistor 15. In addition, since the input common 11 of the second Josephson line 12 and the input end of the fourth Josephson line 14 are connected by the interface 16, the junction of the second Josephson line 12 - the inductance 16 - the input end of the fourth Josephson line 14 A superconducting loop (magnetic flux quantum stop portion) consisting of the Junction-Blunt plane path of the Josephson line 14 of No. 4 is formed to hold the magnetic flux parent and child.

In the structure of the fifth embodiment, the magnetic flux quantum stop can assume three states. 17 is a state where magnetic flux quanta are not retained,
18 is a state in which the magnetic flux quantum is held such that the circulating current associated with the stopped magnetic flux quantum flows from the upper electrode of the line 12 to the upper electrode of the line 13; 19 is a state in which the circulating current is maintained from the upper electrode of the line 13 to the upper electrode of the line 12; This is a state in which magnetic flux quanta are held so that they flow to
It becomes as shown in . In the figure, (input to terminal Tll, input to terminal 13) indicates the input that causes a change, and [output of terminal 12, output of terminal 1 14] indicates the output at that time.

A sixth embodiment will be described using FIG. 8. In FIG. 6, 21 is a first Josephson line, 22 is a second Josephson line, 23 is a third Josephson line, 24 is a resistor, and 25 is a Josephson line forming a series connection of Josephson junctions. junction, T21 is the input end, T22 and T2
3 is the output end. The sixth embodiment creates an inductance loop by connecting the upper electrode at the input end of the line 2 and the upper electrode at the input end of the line 3 with a superconductor (inductance) in the magnetic flux quantum logic element of the first embodiment. Instead, a plurality of Josephson junctions 25 are connected in series, and an inductance loop is constructed by the inductance of the junctions.

A seventh embodiment will be explained using FIG. 9. In FIG. 9, 31 is a first Josephson line, 32 is a second Josephson line, 33 is a third Josephson line, 34 is a resistor, and 35 is a Josephson line forming a series connection of Josephson junctions. junction, Ll is the signal line for reset input signal a, 36 is the magnetically coupled part, T21 is the input end, T2
2 and T23 are output ends. The seventh embodiment is the sixth embodiment.
In the magnetic flux quantum logic device of the embodiment, line 22 and line 2
The signal line L1 is magnetically coupled to one of the Josephson junctions connecting the signal line L1 and the signal line L1. By applying an input to this signal line L1, the Josephson junction in the inductance loop (magnetic flux quantum stopping section) can undergo a voltage transition, and the magnetic flux quantum held in the inductance loop can be released. In other words, the signal line L1 has the function of resetting the magnetic flux quantum stop section.

The eighth embodiment will be explained using FIG. 10. In FIG. 10, M1 to Mn are magnetic flux quantum logic elements of the first embodiment. In this way, the eighth embodiment uses n magnetic flux quantum logic elements of the first embodiment, and connects one of the two output terminals of the first β flux quantum logic element to the 1 + 1st magnetic flux quantum logic element. It is connected in n stages by connecting the input terminals of the logic elements. In the structure of this embodiment, an asymmetric (
1 counter is realized.

〔Effect of the invention〕

As explained above, the magnetic flux quantum logic element and asynchronous counter according to the present invention are capable of forming a flip-flop and an asynchronous counter with an extremely simple structure by forming an inductance loop at the branch of the resistance-coupled branch of the Josephson line. By utilizing the self-shaping effect unique to magnetic flux quanta, there is a great advantage that reduction in margin due to multi-stage connections can be prevented.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram for explaining the first embodiment of the present invention, Fig. 2 is an explanatory diagram showing the relationship between the Ll product and the flux quantum behavior Z) J in the inductance loop section, and Fig. 3 is an explanatory diagram for explaining the operation mode of the first embodiment, FIGS. 4 to 10 are explanatory diagrams for explaining the second to eighth embodiments,
FIG. 11 is a circuit diagram for explaining a conventional magnetic flux quantum logic element. 1. First Josephson line, 2... Second Josephson line, 3... Third Josephson line, 4... Resistor, 5... Inductance, 6... Superconductor, 7.
...Tunnel barrier, T1...Input end, T2. T3・
...Output end.

Claims (5)

[Claims] (1) A Josephson junction in which a tunnel barrier is sandwiched between an upper electrode and a lower electrode made of a superconductor has a long structure in only one direction, with one end serving as an input end and the other end serving as an output end. The first to third Josephson lines are provided, and between the output end of the first Josephson line and the input end of the second Josephson line, and between the output end of the first Josephson line and the third Josephson line. Either the upper electrode and the lower electrode are connected to the input end of the line with a resistor, or one of the upper electrodes and the lower electrode is connected with a resistor, the other is connected with a superconductor, and the second The input end of the Josephson line and the input end of the third Josephson line are connected by a superconductor between the upper electrodes and between the lower electrodes, and the second Josephson line and the third Josephson line are connected. A magnetic flux quantum logic element characterized in that magnetic flux quanta can be held in a superconducting loop composed of a superconductor. (2) The magnetic flux quantum device according to claim 1, which is a Josephson junction in which a tunnel barrier is sandwiched between an upper electrode and a lower electrode made of a superconductor, and has a long structure in only one direction, and has an input terminal at one end. Instead of a Josephson line with one end as an output end and the other end as an output end, multiple Josephson junctions with a tunnel barrier sandwiched between an upper electrode and a lower electrode made of a superconductor are used to connect the upper electrodes using inductance. and a magnetic flux quantum logic element comprising a Josephson line which is connected in only one direction by connecting the lower electrodes to each other, and has one end as an input end and the other end as an output end. (3) In the magnetic flux quantum device according to claim 1, instead of connecting the input end of the second Josephson line and the input end of the third Josephson line with each other by a superconductor, a plurality of Josephson A magnetic flux quantum logic element, characterized in that both input terminals are connected by a series-connected Josephson junction in which junctions are connected in series. (4) The magnetic flux quantum logic device according to claim 1, characterized in that a signal line is magnetically coupled to at least one junction of the plurality of Josephson junctions of the series connection body of Josephson junctions. (5) By using N magnetic flux quantum logic elements according to claim 1 and connecting the first or second output end of the magnetic flux quantum logic element in one stage to the input end of the next stage magnetic flux quantum logic element. An asynchronous counter characterized by N stages connected.