JPS6161278B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes a Giosefson junction line having a configuration in which a tunneling non-superconductor layer is interposed between two striped superconductor layers to form a Giosefson junction. This invention relates to a novel superconducting pulse generator designed to obtain output.

Embodiments of the present invention will be described below in detail with reference to the drawings. FIGS. 1 to 3 show a first embodiment of the present invention, in which a striped superconductor layer 2 is formed on an insulating substrate 1, Further, on the insulating substrate 1 and the striped superconductor layer 2, there is provided an insulator having a striped window 3 that exposes the striped superconductor layer 2 to the outside with a width smaller than the width of the striped superconductor layer 2. A layer 4 is formed, and a striped tunneling non-superconductor layer 5 made of, for example, an insulating layer is formed in the striped window 3 of the insulating layer 4 so as to be in contact with the striped superconductor layer 2, Further, a striped superconductor layer 6 is placed on the insulating layer 4 at a position corresponding to the striped superconductor layer 2, and contacts the non-superconductor layer 5 for tunneling through the striped window 3 of the insulating layer 4. Thus, on the insulating substrate 1, 2
A striped non-superconductor layer 5 for tunneling is interposed between two striped superconductor layers 2 and 6 to form a Josephson junction line 8 having a structure in which a striped Josephson junction 7 is formed. In this case, the length of the striped Josephson junction 7 is selected to be sufficiently longer than the Josephson penetration depth λ _J expressed by λ _J =√2 _{0 c} (1). However (1)
In the formula, h is Planck's constant, e is the electron charge, μ
₀ is the vacuum permeability, d is the parameter expressed as (2λ _L + t ₀ ), where λ _L is the London penetration depth of Josephson junction 7, and t ₀ is the thickness of the non-superconductor layer 5 for tunneling, j _c indicates the maximum Josephson current density of Josephson junction 7.

Further, a striped window 10 is formed in the above-mentioned insulating layer 4 at a position below the striped superconductor layer 6, and a striped resistance layer 11 is formed within the striped window 10 to form a Josephson junction. It is formed extending between the striped superconductor layers 2 and 6 that constitute the line 8.

Further, on the insulating substrate 1, a Josephson junction line 8 is provided.
A striped conductor layer 12 made of a superconductor is formed which can extend outwardly from a plurality of positions along the length of the striped superconductor layer 2 constituting the insulating layer 4. A striped conductor layer 13 similar to the striped conductor layer 12 is formed extending outward from a position corresponding to the striped conductor layer 12 of the striped superconductor layer 6 .

The above is the configuration of the first embodiment of the present invention,
According to such a configuration, the resistance layer 11 is formed by forming a stripe of the Josephson junction line 8 on the Josephson junction line 8 having the Josephson junction 7 which is sufficiently long compared to the Josephson penetration depth λ _J expressed by the above equation (1). Striped conductor layers 12 and 13 are added to the Josephson junction line 8 in such a way that they extend between the superconductor layers 2 and 6, i.e. in a parallel relationship with the Josephson junction 7. It has a configuration in which a current can be applied to a plurality of positions along the length of the Josephson junction 7 using the electric current.

By the way, in the first embodiment of the present invention described above with reference to FIG.
1 and stripe-shaped conductor layers 12 and 13 are not added as described above, that is, a structure with only the Josephson junction line 8, one of the striped superconductor layers 2 and 6 constituting the Josephson junction line 8. The free ends are connected to terminals T1 and T1',
If the other free ends are terminals T2 and T2', as shown in FIG. The Josephson junction 7', the capacitance 21 distributed in the Josephson junction 7', and the quasiparticle resistance 22 of the Josephson junction 7'
An equivalent circuit in which a plurality of unit equivalent circuits represented by parallel circuits are cascade-connected as M1, M2... via inductors 23 of unit length of striped superconductor layers 2 and 6. It has a configuration expressed as follows, and a parameter Γ expressed as Γ=g√2 _c (2).
However, in equation (2), g represents the equivalent conductance per unit area of Josephson junction 7, and ε represents the dielectric constant of non-superconductor layer 5.

Therefore, the configuration of the embodiment of the present invention described above in FIG. 1 is as shown in FIG. 5, in the equivalent circuit described above in FIG.
... is an equivalent circuit M1', M2' for a unit, which has a Josephson junction 7', a capacitance 21, and a resistance 11' for a unit length of the resistance layer 11 connected in parallel with the external quasi-particle resistor 22 of the quasi-particle resistor 22. . . _. and the equivalent circuits M1', M2', . It has a configuration expressed by an equivalent circuit similar to that in Fig. 4 except for , and has a parameter _Γ ′ expressed as In the equation, g' is the sum of the equivalent conductance per unit area of the Josephson junction 7 and the equivalent conductance per unit area of the resistance layer 11), and therefore, in the configuration with only the Josephson junction line 8, ( 2)
It has a configuration in which the value of the parameter Γ in the equation is increased by providing the resistance layer 11,
Furthermore, the magnetic flux quantum at the Josephson junction 7 in the configuration based only on the Josephson junction line 8 is reduced by the current i in the Josephson junction 7 when the conductor layers 12 and 13 are provided.
Due to the Lorentz force caused by the magnetic field in the length direction of the Josephson junction line, which is caused by the flow _{of e} , the terminal T2 is
And on the T2' side, it is accelerated with the acceleration force represented by the parameter γ, which is expressed as γ=i _e /j _c ...(4), and μ=μ ₀ (πγ/4Γ) /√1+(44) ² ... ...Feed rate μ expressed by (5) (However, μ ₀ in equation (5) indicates the speed of the magnetic flux quantum in the configuration with only the Josephson junction line 8, and is expressed as √ _{0 0} )
The signal is transmitted from the terminals T1 and T1' to the terminals T2 and T2'.

For this reason, in the case of the first embodiment of the present invention described above in FIG. 1, a pulse generation voltage source 31 is connected between terminals T1 and T1', and a pulse generation voltage By applying G, the pulse generation voltage G is transmitted from the terminals T1 and T1' to the terminals T2 and T2' at the other end of the Josephson junction line 8, that is, between the terminals T2 and T2'. However _, at _that time, the pulse width is about several times the time τ _{J expressed} as The output pulse F is obtained in a manner corresponding to the time width and amplitude of the pulse generation voltage G. For example, the effective length of Josephson junction line 8 is 30
When λ _J , V ₀ =√ _{c 0} 2 ...(7) has _{an amplitude of 0.4V 0 as} shown in FIG. 6A, and 15τ _J When the voltage obtained at time 5τ _J with _a time _width of If the voltage obtained at time 5τ _J with an amplitude of 1.3V ₀ and a time width of 15τ _J as shown in FIG. 6C is used as the pulse generation voltage G, as shown in FIG. 6D. 2τ as shown
Three pulses having a width of about _J are obtained as a pulse output F successively after a time 40τ _J at intervals of approximately 5τ _J , and further have an amplitude of 9.4 V ₀ as shown in FIG. 6E, and approximately If the voltage obtained from time 5τ _J with a time width of 1τ _J is used as the pulse generation voltage _G , three pulses with a width of about 2τ _J as shown in FIG. Approximately 2.5τ
This is obtained as a pulse output F at intervals of _J.

As mentioned above, the first aspect of the present invention shown in FIG.
According to the embodiment, in the Josephson junction line 8,
By adding an extendable resistive layer 11 between the striped superconductor layers 2 and 6, the Josephson junction line 8 is provided with means for increasing the equivalent conductance of the Josephson junction 7, and the Josephson junction line 8 By adding striped conductor layers 12 and 13 to the Josephson junction 7, the Josephson junction line is provided with means for accelerating the magnetic flux quantum at the Josephson junction 7. It has a great feature in that by applying a pulse generation voltage having a predetermined amplitude to one end of the line 8, a predetermined pulse output can be obtained from the other end of the Josephson junction line 8.

In addition, in the above, Γ of Josephson junction line 8
We have described the case in which the value of is made larger by applying means to increase the equivalent conductance of the Josephson junction line 8 to the Josephson junction line 8 compared to the case where no such means is applied. As shown in the figure, although detailed explanation is omitted, the resistance layer 1 in the configuration described above in FIG.
1 is omitted, however, between the striped superconductor layer 6 and the non-superconductor layer 5 for tunneling, for example,
By inserting a normal conductor layer 41 made of a metal such as Al or Sn, a means for reducing the maximum Josephson current density j _c of the Josephson junction 7 is taken, and the value of the parameter Γ of the Josephson junction 7 is This normal conductor layer 41 can be made larger than that in the case where the above means are not applied.
As mentioned above, one striped superconductor layer 6
Not only between and the tunneling non-superconductor layer 5,
The structure is such that it is inserted between the other striped superconductor layer 2 and the non-superconductor layer 5 for tunneling, or between both striped superconductor layers 2 and 6 and the non-superconductor layer 5 for tunneling. It is also possible. Further, as shown in FIG. 8, although detailed explanation is omitted, the striped conductor layers 12 and 13 in the configuration described above in FIG. An insulating layer 42 is formed on the insulating layer 42 at a position corresponding to the striped superconductor layer 6, and a width gradually decreases from one end to the other end along the Josephson junction line 8. A conductor layer 43 that can be extended is formed, and an accelerating current for magnetic flux quantum is passed from one end of the conductor layer 43 to the other end, and a magnetic field is gradually applied to the Josephson junction line 8 from one end to the other end. By adopting a configuration that provides a magnetic field distribution with a large intensity, it is also possible to accelerate the magnetic flux quantum at the Josephson junction 7.

Note that the Josephson junction line 8 having the above-described configuration in FIGS. 1 to 8 is described as a distributed constant type line, but as shown in FIG. In place of the striped tunneling non-superconductor layer 5 extending along the Josephson junction line 8 in the configuration described above in the figure, by using an interrupted tunneling superconductor layer 45, the lumped constant It could also be a molded line, and various other modifications could be made without departing from the spirit of the invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing an example of a superconducting pulse generator according to the present invention, FIGS. 2 and 3 are sectional views taken along lines - and -, and FIG.
5 and 5 are equivalent circuit diagrams for explaining the superconducting pulse generator according to the present invention, FIG. 6 is a curve diagram showing the input/output characteristics of the superconducting pulse generator according to the present invention, and FIG. 7 is a diagram according to the present invention. A sectional view showing another example of a superconducting pulse generator, and FIGS. 8 and 9 are schematic plan views showing still other examples of the superconducting pulse generator according to the present invention. In the figure, 1 is an insulating substrate, 2 and 6 are striped superconductor layers, 3 and 10 are windows, 4 and 42 are insulating layers, 5 and 45 are non-superconductor layers for tunneling,
7 is a Josephson junction, 8 is a Josephson junction line, 11 is a resistance layer, 12 and 13 are striped conductor layers, 21 is a capacitor, 22 is a quasi-particle resistor, 23 is an inductor, 31 is a voltage source for pulse generation, 41 is a regular Conductor layer, 43 is conductor layer, T1, T1', T2
and T2' indicate terminals, respectively.

Claims (1)

[Scope of Claims] 1. A Josephson junction line having a configuration in which a non-superconductor layer for tunneling is interposed between first and second striped superconductor layers to form a Josephson junction, the On the railway line,
Either or both of the means for increasing the equivalent conductance of the Josephson junction and the means for reducing the maximum Josephson current density of the Josephson junction are applied, so that the parameter _Γ ( However, g is the equivalent conductance per unit area of Josephson junction, h is Planck's constant, and d is λ
_L London penetration depth, t ₀ is the thickness of the non-superconductor layer for tunneling, a parameter expressed as (2λ _L + t ₀ ), e is the electron charge, J _c is the maximum Josephson current density of the Josephson junction, (ε represents the dielectric constant of the tunneling non-superconductor layer) is made larger than that in the case where the above means are not applied, and the magnetic flux at the Josephson junction is increased to the Josephson junction line. A means for accelerating the quantum is provided, and by applying a pulse generation voltage having a predetermined amplitude to one end of the Josephson junction line, a predetermined pulse output can be obtained from the other end of the Josephson junction line. A superconducting pulse generator characterized by its features. 2. In the superconducting pulse generator recited in claim 1, the means for increasing the equivalent conductance of the Josefson junction comprises the first and second
1. A superconducting pulse generator comprising a resistive layer extending between striped superconductor layers. 3. In the superconducting pulse generator recited in claim 1, the means for lowering the maximum Josephson current density of the Josephson junction may be any one of the first and second striped superconductor layers. A superconducting pulse generator comprising a normal conductor layer interposed between one or both of the tunneling non-superconductor layers. 4. In the superconducting pulse generator recited in claim 1, the means for accelerating the magnetic flux quantum in the Josephson junction includes the first and a second striped superconductor layer, each of which has a conductor layer extending from the second stripe-shaped superconductor layer. 5. In the superconducting pulse generator recited in claim 1, the means for accelerating the magnetic flux quanta in the Josephson junction is such that a current for accelerating the magnetic flux quanta is passed from one end to the other end. In this way, in order to give the Josephson junction line a magnetic field distribution in which the magnetic field strength gradually increases from one end to the other end, the A superconducting pulse generator characterized in that it is constructed with a conductor layer that exhibits a narrow width and is extendable.