JPH0786647A - Superconducting element and its manufacture - Google Patents

Abstract

PURPOSE:To provide a fast new-function-element of low-energy-consumption provided with at least two superconducting joint parts, connected in series. CONSTITUTION:This element consists of the first superconducting joint part wherein at least two incidence electrodes, into which quasiparticles come in, are provide and assigned with such electrode interval (intervals between superconducting electrodes 101, 102 to 103) as will cause andreyer reflection, however with no connection in super-conduction manner, and the second superconducting joint part connected to it in series in superconducting manner (superconducting electrodes 103 to 104), and further, a means that controls amplitude of superconducting wave motion function leaking from the superconducting joint part (control electrodes 500 and 501) is included. The counter electrodes of the first super-conduction joint part is provided with a step-like shape so that the quasiparticles subjected to the andreeffu reflection will interfere. With the current made to flow in the first superconducting joint part as an input and the state of the second one as an output, a superconducting element provided with a threshold logic function that allow adjustment of input signal weight by a single element with the control electrode is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention comprises at least two superconducting junctions connected in series, at least one of the superconducting junctions comprising at least two electron wave incident electrodes. The present invention also relates to a superconducting element having low power consumption and a new function.

[0002]

2. Description of the Related Art Conventionally, a superconducting element having a plurality of superconducting conductive electrodes has been disclosed in Japanese Patent Laid-Open No. 1-132178. In this conventional technique, for example, as shown in FIG. 1, four superconducting conductive electrodes, which are a source, a drain, and a control electrode, are coupled via a common normal conductor, and a voltage is applied from the control electrode. There is a switching element (superconducting transistor).

[0003]

Among the conventional techniques,
In the superconducting element, the only function that can be performed is a simple switching operation by controlling the superconducting current by applying a voltage to the control electrode.

An object of the present invention is to provide an ultrahigh-speed, low-power-consumption functional superconducting device having a novel operating principle.

[0005]

In order to achieve the above object, a superconducting element of the present invention comprises a first superconductor having a step structure on at least one side, and a stepped side of the first superconductor. And a first superconducting junction composed of at least two incident electrodes for injecting quasi-particles through the normal conductor, and a normal conductor facing the stepless side of the first superconductor. And a second superconducting joint portion in which a second superconductor is arranged so as to be connected in series via the above-mentioned normal conductor in the first and second superconducting joint portions. It is characterized in that it is configured so as to include means for controlling the amplitude of the seeping superconducting waveguide function.

[0006]

In the superconducting element of the present invention, at least two incident electrodes are provided, and a structure in which quasi-particles are incident on a first superconductor having a step structure via a normal conductor is used. A first superconducting junction in which the incident electrode and the first superconductor are arranged so that a current does not flow, and the first superconducting junction is connected in series to the first superconducting junction.
The second superconductor and the second superconductor are superconductingly coupled by the Josephson effect so that the superconducting current flows.
Of the second superconducting joint in which the superconductor of FIG. At the first superconducting junction, a deviation from Ohm's law is observed due to excess current due to Andreev reflection that occurs at the boundary between the superconductor and the normal conductor. The second superconducting junction transitions from the superconducting state to the voltage state due to the addition of the currents having this non-linear characteristic. That is,
The sum of the currents flowing through the second superconducting junction is I = ΣI _k
When I exceeds the critical current, the second superconducting junction changes from the superconducting state to the voltage state. Here, I _k is a current flowing from the k-th superconducting electrode forming the first superconducting junction. Further, this I _k is I _k = w _k i _k
It can be expressed as. That is, w _k is the weight of the current (input signal) flowing between the k-th superconducting electrodes. The weight reflecting this excess current can be controlled by changing the distance between the superconducting conductive electrodes forming the first superconducting junction and the width of the superconducting conductive electrodes (normal conduction resistance, Andreyev reflectance).

The non-linear characteristic of the first superconducting junction due to excess current is the non-linearity reflecting the interference due to the provision of a step structure that causes quasi-particle interference in the counter electrode portion of the first superconducting junction. It is possible to obtain the characteristics with emphasis. Furthermore, in the first or second superconducting junction, the superconducting waveguide function seeps into the normal conductor due to the superconducting proximity effect. The length of the bleeding distance (bleeding length) depends on the substance of the normal conductor. Especially when a semiconductor is used as the normal conductor, the exudation length is 3 times the semiconductor carrier concentration.
It is proportional to the 1st power. By using these properties, the functionality of the superconducting device according to the present invention described below can be realized.

In order to realize the functionality of the superconducting element according to the present invention, a control electrode for applying a voltage is provided to a local portion or the whole of the first or second superconducting junction, and the voltage is applied to this. The carrier concentration may be controlled by controlling. As described above, when a voltage is applied to the control electrode provided in the first superconducting junction, the seeping length of the first superconducting junction becomes long, so that Andreev reflection that occurs in the first superconducting junction occurs. The excess current due to
The weight of the current (input signal) flowing through the superconducting junction of is changed. Also, for the same reason, it becomes possible to increase the critical current by applying a voltage to the control electrode provided in the second superconducting junction. By using the above controllability, it becomes possible to realize a superconducting element having a threshold logic function in which the weight and threshold value of an input signal are variable. The most basic application is the AND and OR logic functions realized by the threshold logic function of the superconducting element alone according to the present invention, and the weighted addition operation function. Further, it becomes possible to realize a superconducting device having a threshold logic function in which the input weight and the output threshold can be changed at the same time.

[0009]

EXAMPLES The present invention will now be described in detail with reference to examples.

(Embodiment 1) FIG. 1 is a top view of a superconducting element according to a first embodiment of the present invention. FIG. 2 is a sectional view of a superconducting-normal conducting two-layer film which is the basis of the superconducting device according to the first embodiment of the present invention. FIG. 3 is a sectional view showing an AA ′ section in FIG. 1 of the first embodiment of the present invention. The superconducting element according to the present invention has at least two portions where the superconductors face each other with the normal conductor interposed therebetween. One of these superconducting junctions is configured to be superconductingly coupled by the Josephson effect, and the other is formed so that superconducting coupling does not occur.

First, a basic manufacturing process of the superconducting device according to the present invention will be described with reference to FIG. The thickness of the substrate 119 made of silicon single crystal is about 2 by the thermal oxidation method.
A 00 nm silicon dioxide film 120 was formed. Next, after forming a thin film of Al having a thickness of 100 nm by a molecular beam method in a high vacuum, a thickness 1 of a superconductor Nb formed by a molecular beam method in the same high vacuum is used.
A superconducting layer 100 having a thickness of 00 nm was formed. In the above process, the Al layer that is the normal conductor layer 201 and the superconductor layer 1
A layer of Nb of 00 was continuously formed without being taken out into the air. Therefore, a good interface between the normal conductor and the superconductor necessary for producing the superconducting junction using the proximity effect can be obtained.

The normal conductive layer 201 and the superconductor layer 100 described above are used.
By using the resist pattern formed by the electron beam direct drawing method as a mask, the two-layered film made of the above is processed by the reactive ion etching method to form a plurality of opposed superconducting electrodes 102, 103, 104 as shown in FIG. The superconducting junction part containing it is obtained.

Next, referring to the top view (FIG. 1) of the superconducting element according to the first embodiment of the present invention, the superconducting electrodes 101, 102, 103, 104 and the first and second superconducting electrodes formed by using the superconductor Nb will be described. The structure of the superconducting element including a superconducting junction is shown. Superconducting electrodes 101 and 102 are provided to inject quasi-particles by a bias voltage, and superconducting electrodes 103 and 104 are provided to form a second superconducting junction. Superconducting electrodes 103 and 104 are superconductingly coupled via a normal conductor 201 by a superconducting proximity effect. That is, the superconducting electrodes 103 and 104
The Josephson effect occurs between the two, which causes superconducting current to flow. On the other hand, the superconducting electrodes 101 and 102 and the superconducting electrode 103 are not superconductingly coupled. That is, no superconducting current flows between these electrodes. But,
Between the superconducting electrodes 101 and 102 and the superconducting electrode 103, the electrode intervals of the superconducting electrodes are set so that a special scattering phenomenon (Andreev reflection) of quasi-particles that occurs at the interface between the superconductor and the normal conductor occurs. Further, a step shape is provided on the counter electrode (superconducting electrode 103) of the first superconducting junction. This shape causes interference with the Andreev-reflected quasiparticles.

Next, an example of the processing dimension of the weak connection will be shown. Figure 1
The width of the superconducting electrodes 101 and 102 shown in FIG.
And the width of 103 and 104 is 10 μm. The intervals between the superconducting electrodes 101 and 103 and 102 and 103 of the first superconducting junction where the superconducting electrodes are opposed to each other via the normal conductor are 0.5 μm. The distance between the superconducting electrodes 103 and 104 of the second superconducting junction is 0.2 μm. This size is an example, and the size is not limited to this. The recommended size is such that the width of each superconducting electrode is 50 to 0.2 μm, and the size of the interval between the first superconducting junctions where the superconducting electrodes are opposed to each other via the normal conductor is 50 to 0.05 μm. The distance between the second superconducting junctions is 50 to 0.2 μm. More desirable size is such that the width of each superconducting electrode is 2 to 0.5.
μm, and the dimension of the interval between the first and second superconducting junctions in which the superconducting conductive electrodes face each other via the normal conductor is 0.5 to
It is 0.1 μm.

A characteristic curve 10 in FIG. 4 is a current-voltage characteristic of the superconducting element in the first embodiment of the present invention. As described above, the superconducting electrodes 101, 103 and 1
Between 02 and 103, there is obtained a characteristic indicating an excess current deviated from Ohm's law due to Andreev reflection and an oscillation of excess current due to interference of quasi-particles subjected to Andreev reflection. The interference of the quasi-particles occurs because the quasi-particles subjected to Andreev reflection have a path difference due to the step shape of the counter electrode. The structure generated in the characteristic reflecting the interference of the quasi-particles changes depending on the step shape of the counter electrode and the distance between the superconducting conductive electrodes of the first superconducting junction. Characteristic curves 11 and 12 in FIG. 4 respectively show the characteristics when the step is increased and the distance between the electrodes is reduced and when the step is decreased and the distance between the electrodes is increased. Furthermore, these characteristics show a significant non-linearity when the second superconducting junction transitions to the voltage state. Due to this element characteristic, the superconducting element of the present invention can be used as a logic element having a non-linear weighted threshold characteristic.

The basic operation for controlling the characteristics of this element is possible by a magnetic field generated by passing an electric current through a control line provided in parallel with the superconducting electrodes 101, 102, 103. At this time, the region where the superconducting waveguide function is exuded in the first and second superconducting junctions becomes small, so that the interference intensity of the quasi-particles generated in the first superconducting junction becomes small and the criticality of the second superconducting junction The current value decreases and the characteristic change shown in FIG. 5 is obtained. Similar modulation of the critical current value of superconducting weak coupling can be realized by providing a waveguide for irradiating microwaves or lasers and irradiating microwaves or lasers. In FIG. 5, the characteristic curve 10 is the result when no magnetic field is applied, and the characteristic curve 30 is the result when the magnetic field is applied.

The current-voltage characteristics shown in FIGS. 4 and 5 can be obtained by cooling the superconducting element of the present invention in liquid helium.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG. The manufacturing process and materials used for the superconducting device of this embodiment may be the same as those of the first embodiment of the present invention. However, the present embodiment is different in that single crystal Si is used as the normal conductor, and that the control electrode 500 is formed above the normal conductor of the second superconducting junction that is superconductingly coupled. ing. Thus, the control electrode 500
By providing the above, it becomes possible to change the critical current of the second superconducting junction. Therefore, the superconducting element of the present invention can be used as a logic element having a function of controlling the threshold value.

FIG. 7 shows current-voltage characteristics of the superconducting device according to the present invention when the voltage applied to the control electrode 500 is changed. In FIG. 5, the characteristic curve 10 is the result when the control voltage is not applied, and the characteristic curve 20 is the result when the control voltage is applied. Since the critical current of the second superconducting junction increases, it becomes possible to control the threshold value of the voltage at which the characteristics change abruptly.

By using the threshold logic function of the superconducting element according to the present embodiment, the following AND or OR logic circuit function can be realized by a single element.

First, consider the case where no gate voltage is applied to the second superconducting junction. Whether the second superconducting junction is in the superconducting state or in the voltage state is regarded as the output. At this time, an OR logic circuit as shown in FIG. 8 can be configured with the bias voltage corresponding to the flow of the critical current of the second superconducting junction as the threshold value. In FIG. 6, X1 and X2 represent inputs by the currents flowing from the two superconducting electrodes to the first superconducting junction. In this case, when the current injected from any one of the superconducting electrodes of the first superconducting junction exceeds the critical current of the second superconducting junction, the second superconducting junction becomes a voltage state.
OR operation. Then, as represented by Figure 9, AN
The D operation will be described. At this time, a gate voltage is applied to set the critical current of the second superconducting junction, that is, the threshold value to double. By doing so, the second superconducting junction transitions to the voltage state only when the sum of the currents input from the first superconducting junction exceeds the critical current of the weak coupling portion 2, and AND
It becomes possible to operate.

The operation of the device in this embodiment is performed by cooling the superconducting device of the present invention in liquid helium, and then controlling the control electrode 500.
Can be carried out by applying a voltage to.

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to FIG. The manufacturing process and materials used for the superconducting element of this embodiment may be the same as those of the second embodiment of the present invention. However, the present embodiment is different in that the control electrode 510 is also formed on the normal conductor of the first superconducting junction which is not superconductingly coupled. By applying a voltage to the control electrode 510, the region where the superconducting waveguide function exuded in the normal conductor of the first superconducting junction increases is increased, so that the interference intensity of the quasi-particles subjected to Andreev reflection (excessive Current value) changes. Therefore,
A superconducting element having a threshold logic function capable of controlling the weight of the current (input signal) flowing through the first superconducting junction having a plurality of superconducting conductive electrodes by changing the voltage applied to the control electrode 510 is provided. It becomes feasible.

The superconducting electrode 101 (or 1
The current-voltage characteristics between 02) and 104 are shown in FIGS.

The current-voltage characteristic of FIG.
This is a change in characteristics when a voltage is applied to the control electrode 500 without applying a voltage to the control electrode 500. In FIG. 11, the characteristic curve 10 is the result when a voltage is not applied to any control electrode, and the characteristic curve 20 is the result when a control voltage is applied to the control electrode 500. This change in characteristics is the same as the change in characteristics shown in the second embodiment of the present invention. That is, when a voltage is applied to the control electrode 500, the second
The critical current of the superconducting junction of 1 increases, and the value of the threshold voltage at which the characteristics change rapidly changes.

The current-voltage characteristic of FIG.
This is a change in characteristics when a voltage is applied to the control electrode 510 without applying a voltage to the control electrode 510. In FIG. 11, characteristic curve 10 is the result when no voltage is applied to any control electrode, and characteristic curve 20 is the result when a control voltage is applied to control electrode 510. At this time, the control electrode 510
When a voltage is applied to the superconducting proximity effect, the region in which the superconducting waveguide function seeps into the normal conductor of the first superconducting junction expands due to the superconducting proximity effect, so that the excess current flowing in the first superconducting junction increases. In addition, the region exuding in the normal conductor of the first superconducting junction is enlarged, and the path difference between the quasi-particles subjected to Andreev reflection that contributes to the interference is reduced. Become.

Using the combination of the characteristics that change depending on the voltage applied to the control electrode 500 or 510,
The threshold logic function as shown in FIG. 13 can be realized by the superconducting element of the present invention.

In FIG. 13, X1 and X2 are inputs by a current flowing from the two superconducting electrodes to the first superconducting junction, and Vg1 and Vg2 are control electrodes 510 and 500, respectively.
Indicates the voltage applied by. w and T represent weights and threshold values that change depending on the applied voltage. The characteristic of the superconducting element having this threshold logic function is that the control electrode 5
By applying the voltage (Vg1) by 10, the weights of the input signals from X1 and X2 can be controlled in parallel.

The current-voltage characteristics shown in FIGS. 11 and 12 can be obtained by cooling the superconducting element of the present invention in liquid helium.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. The manufacturing process and materials used for the superconducting element of this embodiment may be the same as those of the second embodiment of the present invention. However, this example is different in that a plurality of control electrodes 510 and 511 are provided above the first superconducting junction. With the configuration of this element, a superconducting element having a threshold logic function capable of controlling the weight and threshold value of each input as shown in FIG. 15 can be realized. In FIG. 15, X1 and X2 are inputs by a current flowing from the two superconducting electrodes to the first superconducting junction, and Vg
1, Vg2 and Vg3 are control electrodes 510, 51, respectively.
The voltage applied to 1,500 is shown. w1 and w2 are weights that change according to Vg1 and Vg2, respectively, and T is V
The threshold value which changes with g3 is shown.

First, the weight applied to the second superconducting junction can be independently controlled by the voltage applied to the control electrodes 510 and 511. Further, as in the case of Example 3 described above, the critical current of the second superconducting junction that determines the output threshold value can be controlled by the gate voltage applied to the control electrode 500. Therefore, the threshold logic function shown in FIG. 15 can be realized by one superconducting element.

The above device operation was obtained by cooling the superconducting device according to the present invention in liquid helium.

In the above embodiments, Nb is used as the superconductor.
Was used, but instead of this, Pb, or an alloy of Pb, N
b intermetallic compound such as NbN, Nb Sn, Nb G
It goes without saying that e, Nb Al, Nb Si or the like may be used. Further, although Al is used as the normal conductor, it is needless to say that the object of the present invention can be achieved by using Au, Ag, Cu, or a semiconductor or a semiconductor compound such as Si, GaAs, or InAs instead. .

In the above-described embodiment of the present invention,
Although only two superconducting conductive electrodes and control electrodes are input to the first superconducting junction, the same effect can be realized when the number is three or more.

[0035]

According to the present invention, a first superconducting junction having a plurality of incident electrodes, a second superconducting junction formed by connecting to the first superconducting junction in series, and further comprising: It is configured to include means for controlling the amplitude of the superconducting waveguide function exuded in the normal conductor forming the first and second superconducting junctions. The superconducting electrodes forming the first superconducting junction are not superconductingly coupled to each other, and are formed with an electrode interval such that Andreev reflection occurs at the boundary between the superconductor and the normal conductor. The respective superconducting electrodes forming the second superconducting junction are formed so as to be superconductingly coupled. In the first superconducting junction, the counter electrode for injecting the quasi-particles from the incident electrode is provided with a step shape so that the quasi-particles subjected to Andreev reflection interfere with each other.

In this element structure, when the sum of the currents (inputs) flowing through the first superconducting junction exceeds the critical current of the second superconducting junction, the second superconducting junction transitions from the superconducting state to the voltage state. Therefore, when the current flowing through the first superconducting junction is input and the state of the second superconducting junction (superconducting state or voltage state) is output, a superconducting element having a threshold logic function can be realized by a single element. Further, the current (input signal) flowing in the first superconducting junction controls the weight of the input signal by the interference of quasi-particles due to Andreev reflection and the voltage applied to the control electrode provided in the first superconducting junction. The threshold value can be controlled by applying a voltage to the control electrode provided in the second superconducting junction to change the critical current of the second superconducting junction. Depending on the arrangement of the control electrodes, the weight of the input signal can be realized by applying a voltage from one control electrode to parallel processing the weights of a plurality of inputs or independently controlling a plurality of inputs. By utilizing these characteristics, it is possible to realize the function of a simple AND or OR logic circuit, and further, it is possible to realize multiple input variable weights and threshold variable threshold logic functions with a single element. Further, the superconducting weak coupling has an advantage that a superconducting element having a planar structure and a proximity effect type, which can be highly integrated, and has an ultrahigh speed and low power consumption can be realized.

[Brief description of drawings]

FIG. 1 is a top view of a superconducting element according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a superconducting-normal conducting two-layer film which is the basis of the superconducting device according to the first embodiment of the present invention.

FIG. 3 is an A- line in FIG. 1 according to a first embodiment of the present invention.
It is a sectional view showing an A'section.

FIG. 4 is a current-voltage characteristic showing the operating characteristic of the superconducting element in the first example of the present invention.

FIG. 5 is a change in current-voltage characteristics due to application of a magnetic field of the superconducting element in the first example of the present invention.

FIG. 6 is a top view of a superconducting element according to a second embodiment of the present invention.

FIG. 7 is a current-voltage characteristic showing the operating characteristic of the superconducting element in the second example of the present invention.

FIG. 8 is a conceptual diagram of logical functions (OR logic) realized by the second embodiment of the present invention.

FIG. 9 is a conceptual diagram of logical functions (AND logic) realized by the second embodiment of the present invention.

FIG. 10 is a top view of a superconducting device according to a third embodiment of the present invention.

FIG. 11 is a current-voltage characteristic showing the operating characteristic of the superconducting element in the third example of the present invention.

FIG. 12 is a current-voltage characteristic showing the operating characteristic of the superconducting element in the third example of the present invention.

FIG. 13 is a conceptual diagram of the threshold logic function realized by the third embodiment of the present invention.

FIG. 14 is a top view of a superconducting device according to a fourth embodiment of the present invention.

FIG. 15 is a conceptual diagram of a threshold logic function realized by the fourth embodiment of the present invention.

[Explanation of symbols]

101, 102, 103, 104 ... Superconducting conductive electrode (N
b), 1, 2 ... Superconducting junction, 119 ... Silicon substrate,
120 ... Silicon dioxide film, 201 ... Normal conductor layer (A
l) 10 ... Current-voltage characteristics when no control voltage is applied, 20 ... Current-voltage characteristics when control voltage is applied, 11, 12 ... Electrode spacing and step difference of the first superconducting junction Change in characteristics when applied, 30 ... Change in characteristics when a magnetic field is applied.

Claims (17)

[Claims] 1. A first superconductor having a step on at least one of first and second sides facing each other, and a quasi-particle formed on a first side of the first superconductor via a normal conductor. At least two incident electrodes formed of a superconductor for injecting, a second superconductor formed on the second side of the first superconductor via a normal conductor, and a stain in the normal conductor. Means for controlling the amplitude of the superconducting waveguiding function described above, and a superconducting element. 2. The superconducting element according to claim 1, wherein the width of the incident electrode is narrower than the width of the first superconductor. 3. The superconducting element according to claim 1, wherein the incident electrode and the first superconductor are arranged at an interval such that Andreev reflection can occur at the interface of the normal conductor. And superconducting element. 4. The superconducting element according to claim 1, wherein at the interface of the normal conductor, the first superconductor and the second superconductor are arranged at intervals such that a superconducting current can flow due to the Josephson effect. Are formed. 5. The superconducting element according to claim 1, wherein the reflection probability of causing Andreev reflection can be controlled by the width and step shape of the first superconductor facing the incident electrode. A superconducting element characterized in that 6. The superconducting element according to claim 1, wherein the means for controlling the amplitude of the superconducting waveguiding function exuded in the normal conductor has the amplitude of the superconducting waveguiding function exuded in the normal conductor. A superconducting element, which is arranged so that it can be controlled locally or in the entire region. 7. The superconducting element according to claim 6, wherein the control electrode controls the amplitude of a superconducting waveguide function exuding in a normal conductor between the first superconductor and the incident electrode. A superconducting element, wherein a control electrode is arranged so as to control the magnitude of excess current to each superconducting electrode due to reflection. 8. The superconducting element according to claim 1, wherein the value of the excess current flowing between the superconductors due to the interference of electron waves generated by the step structure provided in the first superconductor. The superconducting element, wherein the incident electrode, the first superconductor and the control electrode are arranged so as to be controlled as a change in 9. The superconducting element according to any one of claims 1 to 8, wherein between the first superconductor and the second superconductor is determined by the total value of the currents flowing from the incident electrode to the first superconductor. A superconducting element, in which a control electrode is arranged so that a threshold element that outputs a superconducting state and a voltage state can be realized by a single element. 10. The superconducting element according to claim 9,
A superconducting element, wherein the control electrode is arranged so that a weighted addition operation can be performed by controlling an input value with a control electrode provided above the first superconducting junction. 11. The superconducting element according to claim 9,
A superconducting device, characterized in that the threshold value of the threshold logic function can be controlled by a control electrode provided above the first and second superconductors. 12. The superconducting element according to claim 9,
A superconducting device in which the incident electrode, the first and second superconductors, and a control electrode are arranged so that an AND or OR logical function can be realized by a single device using a threshold logical function. 13. The superconducting element according to claim 1,
The superconducting element is characterized in that the means for controlling the superconducting critical current is application of a magnetic field, and is configured to include a control line for enabling the application of the magnetic field. 14. The superconducting device according to claim 1,
A superconducting element, wherein the means for controlling the superconducting critical current is a waveguide or a conductor for irradiating a high frequency microwave. 15. The superconducting device according to claim 1,
A superconducting device characterized in that the means for controlling the superconducting critical current is a waveguide or an optical fiber for guiding laser light. 16. The superconducting element according to claim 1, wherein the superconductor is a material selected from lead, a lead alloy, niobium and a niobium intermetallic compound, and the normal conductor is gold. , Silver, copper, or aluminum and its alloys or semiconductors or semiconductor compounds, such as Si, GaA
A superconducting device comprising at least one material selected from s, InAs and compounds thereof. 17. A first superconductor having a stepped structure on at least one side, and at least two facing superposed sides of the first superconductor and injecting quasi-particles through a normal conductor. The first superconducting junction composed of the incident electrode and the second superconductor are arranged so as to be connected in series so as to face the stepless side of the first superconductor through a normal conductor. A second superconducting junction, and
And a means for controlling the amplitude of the superconducting waveguiding function exuded in the normal conductor forming the second superconducting junction, and the first superconducting junction is provided with the first superconducting junction.
By using the excess current due to Andreev reflection that occurs at the interface between the superconductor and the normal conductor and the Josephson effect that occurs at the second superconducting junction, weighted addition and logical functions can be realized with a single element. A method for manufacturing a superconducting element including a step of processing a superconducting film of a weakly coupled portion using at least an electron beam direct writing method in a superconducting element characterized by having a threshold logic function.