JPH09237923A - Superconductive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable improvement of a detection system of an optical signal as an input signal to a superconductive single magnetic flux quantum logic circuit, etc., that is, an input speed of a signal according to an operational speed of a superconductive logic circuit, and optical detection ranging over THz zone while eliminating the influence of light on a peripheral circuit. SOLUTION: This superconductive circuit has a superconductive optical detection part 110 which generates a pulse by an impedance which changes according to the radiation of an optical signal on an impedance modulation part 111 consisting of a superconductor film, etc., and a superconductive single magnetic flux quantum generation part 120 which produces or shapes single magnetic flux quantum making the pulse as the trigger, and it converts the optical signal into single magnetic flux quantum. A photosensitive part is provided to a part of a superconductor film which constitutes a superconductive electromagnetic wave transmission line, and a line end at a position apart therefrom is made an output terminal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting circuit used as an input circuit or the like of an ultrahigh speed superconducting logic circuit.

[0002]

2. Description of the Related Art "Yes" / "No" of magnetic flux quantized in units of magnetic flux quantum Φ ₀ (= 2.07 × 10 ^-15 Wb) realized in an inductance loop in a superconducting circuit is "1" / " 0 ”
In addition, the RSFQ logic (Rapid Single Flux Quantum Lo
gic) and other logic circuits are being developed (for example, KK
Likharev et al., IEEE Trans. Appl. Supercond. Vol.
1, 3-28 (1991)). This kind of single magnetic flux quantum (Single
In a logic circuit using Flux Quantum), a voltage pulse with a pulse width of about ps that can be generated using Josephson elements (Φ ₀ when integrated over time, the corresponding magnetic flux density in space is integrated). Then Φ ₀ ) is used.

The essential upper limit of the calculation speed of the logic circuit using the quantized magnetic flux pulse is determined by the minimum time that can be circuitally separated when the interval between the two pulses is reduced, and the magnetic flux quantum Φ ₀ is It is expressed as a value divided by the critical current-normal resistance product (Ι _c · R _n product) of the Josephson device (which has no hysteresis in the current-voltage characteristic) used in this circuit. For example, if the product of Ι _c · R _n is 2 mV, it is possible to operate at frequencies up to 1 THz in the integrated circuit.
So far, an example of operating a small RSFQ logic circuit at a clock frequency of up to 370 GHz has been reported (BIBunyk et al., Appl. Phys. Lett., 66, 646 (199
Five)).

Further, in the superconducting circuit, impedance matching between the wiring and the element can be easily realized, and the propagation delay is not limited by the CR time constant of the wiring as seen in an integrated circuit using semiconductor transistors. Since the propagation delay is determined by the time that the signal moves at the speed of the electromagnetic wave in the transmission line, the superconducting circuit can operate at a very high speed.

As described above, a logic circuit using a single magnetic flux quantum has a very high potential in its high speed. Furthermore, in recent years, without hysteresis Josephson device having iota _c · R _n product of several mV using an oxide high-temperature superconductor has been achieved, thereby greatly exceeding the Josephson device using a metal-based superconductor Realization of calculation speed is expected.

By the way, FIG. 15 shows a circuit configuration for inputting from the semiconductor circuit 1 as a room temperature device to the superconducting single magnetic flux quantum logic circuit 3 using the coaxial cable 2 and the like. When it comes to a logic circuit that operates at a high speed up to 1 THz, it is very difficult to directly input an ultra-high speed signal suitable for the high speed from the outside using the coaxial cable 2 or the like. This is because if the signal frequency becomes extremely high and the loss due to the cable 2 becomes large, the size of the connection part cannot be ignored for the wavelength corresponding to that frequency, and it becomes very susceptible to the effect of stray impedance. In addition, a wide band is used so that reflection between the external high-impedance semiconductor circuit 1 and the superconducting logic circuit 3 and the coaxial cable 2 between them does not cause a signal different from the original signal to be input. This is because it is necessary to make impedance matching and electromagnetic field mode matching, and it is usually necessary to introduce a plurality of signal inputs.

On the other hand, in order to solve the above-mentioned problems, instead of using an electric signal using a pulse train of "0" and "1" as an input signal, for example, an ON / OFF-modulated optical signal is used. The input method is being tried. FIG.
An optical modulation signal is sent from a semiconductor circuit 1 as a room temperature device to an optical detection unit 5a of an optical-single magnetic flux quantum conversion circuit 5 via an optical cable 4 such as an optical fiber, where it is converted into an electric signal. A circuit configuration is shown in which a single magnetic flux quantum is generated by the single magnetic flux quantum generating unit 5b connected to the photodetector 5a in a low temperature region and the single magnetic flux quantum is input to the superconducting single magnetic flux quantum logic circuit 3. .

The most important input system using such light is the photodetector 5a, which has hitherto been metal / semiconductor /
Attempts have been made to use metal (MSM) diodes, laser diodes for optical modulation, and optical fibers for cables (Chia-c).
hi Wang et al. IEEE Trans. Appl. Supercond., 5,3156
(1995)). As a result, with this MSM diode, 38Gb
A resolution of / s is obtained at a temperature of 2K.

In the input system using the optical signal described above, various types such as an optical fiber and a lens of an optical system can be used,
Moreover, by using these, a signal having a higher frequency than an electric signal can be easily handled in the form of light. Further, for the high speed modulation of the optical signal, direct modulation by a semiconductor laser, external modulation using an optical waveguide, traveling wave type external modulation, or the like can be used, and modulation at a higher frequency is possible.

Since one is light and the other is a single magnetic flux quantum (a voltage pulse of a fixed form in terms of an electric circuit),
Since it is not necessary to directly perform impedance matching between the two and it is not necessary to consider stray impedance and the like in the signal introducing portion to the superconducting single magnetic flux quantum logic circuit 3, it is possible to easily introduce the signal. it can. Further, as is well understood when considering that the signal is introduced into the optical-single magnetic flux quantum conversion unit by the optical fiber, the influence of external electromagnetic noise (particularly low frequency noise) is caused because the conductor is not used for the signal introduction cable. Also, crosstalk is unlikely to occur even when a plurality of signals are input.

As described above, by applying the input method using the optical signal, the input signal can be introduced into the superconducting single magnetic flux quantum logic circuit easily and at a relatively high speed.

[0012]

However, in the conventional optical-single-flux quantum conversion circuit using a semiconductor circuit as the photodetector, the input speed of a signal commensurate with the operation speed of the superconducting single-flux quantum logic circuit. Therefore, it was difficult to obtain the essential maximum performance of a superconducting single-flux-quantum logic circuit, which is characterized by ultra-high-speed operation. As a light-receiving element that uses a metal-based superconductor, one that utilizes the non-equilibrium superconducting phenomenon of a superconducting thin film has been studied, but its response speed is not as fast as it approaches THz. It's not a solution to the problem.

Further, regarding the light receiving portion, when detecting a high-speed signal, it is necessary to dispose the light receiving portion in the immediate vicinity of the signal detecting portion in order to avoid the waveform from becoming dull due to the influence of the time constant. On the other hand, due to the nature of shining light, there is a possibility that the light may affect the peripheral circuit part made of the superconducting circuit, so that there is a problem that the light receiving part cannot be brought very close to the signal detecting part.

As described above, in order to sufficiently bring out the performance of the superconducting single magnetic flux quantum logic circuit or the like, it is important to improve the detection method of the optical signal as the input signal. Specifically, to realize an input speed of a signal corresponding to the operation speed of the superconducting single-flux quantum logic circuit and to eliminate the influence of light on the surrounding superconducting circuit portion without blunting the input waveform. In addition, it has been a problem to be able to separate the light receiving part from the signal detecting part. The present invention has been made to address such a problem, and an object of the present invention is to provide a superconducting circuit capable of sufficiently extracting the performance of a superconducting single-flux quantum logic circuit or the like. Is a superconducting circuit that realizes a signal input speed that matches the operation speed of a superconducting single-flux quantum logic circuit, and prevents the blunting of the input waveform, and it is possible to eliminate the effect of light on the peripheral circuit part. The purpose of the present invention is to provide a superconducting circuit.

[0015]

A first superconducting circuit according to the present invention is provided with a superconducting light guide detecting section which is irradiated with an optical signal and generates a pulse by an impedance which changes by the irradiation of the optical signal, and the pulse is used as a trigger. And a superconducting single-flux-quantum generating unit that generates or shapes a single-flux-quantum, and converts the optical signal into the single-flux-quantum.

The second superconducting circuit is provided at at least one light receiving portion of the superconducting film forming the superconducting electromagnetic wave transmission line and at least one or more line ends of the superconducting electromagnetic wave transmitting line. And an output terminal connected to the output terminal.

In the first superconducting circuit, the superconducting film, the superconducting coupling, and the portion having superconductivity due to the proximity effect are irradiated with light, and a pulse is generated by the impedance of this portion which changes at high speed. , This pulse is used as a trigger to generate or shape a single flux quantum. From the irradiation of the optical signal to the generation of the single magnetic flux quantum, it is possible to obtain an ultrahigh speed single magnetic flux quantum train corresponding to the optical signal because it is based on the above-mentioned ultrahigh speed impedance change.

Further, in the second superconducting circuit, by irradiating the light receiving portion provided on a part of the superconductor film forming the superconducting electromagnetic wave transmission line with light, the optical response output waveform of the light receiving portion is distorted. Can be taken out from the output terminal at an appropriate distance from the light receiving section. Therefore, it is possible to dispose the detection unit at a position away from the light receiving unit that is not affected by light.

[0019]

Embodiments of the present invention will be described below.

First, an embodiment of the first superconducting circuit of the present invention will be described. FIG. 1 is a block diagram showing an example of the configuration of a superconducting logic circuit having the first superconducting circuit of the present invention as an input circuit. 100 is a superconducting light guide-single flux quantum conversion circuit, and 200 is a superconducting single flux quantum logic. Circuit.

A superconducting light guide-single magnetic flux quantum conversion circuit 100, which is an embodiment of the first superconducting circuit of the present invention, includes a light receiving portion for an optical signal, and an impedance that changes according to the optical signal applied to the light receiving portion. It has a superconducting light guide detection unit 110 that generates a pulse and a superconducting single magnetic flux quantum generation unit 120 that generates or shapes a single magnetic flux quantum by using this pulse as a trigger.

The above-mentioned superconducting light guide detecting section 110 is, for example, as shown in FIG. 2, a light receiving section for an optical signal p, and a superconductor such as an oxide superconducting film whose impedance changes according to the applied optical signal p. It can be realized by the impedance modulation section 111 made of a film and the trigger pulse generation section 112 that generates a trigger pulse by the impedance change of the impedance modulation section 111. As the impedance modulator 111, a grain boundary included in the oxide superconductor film, a Josephson junction, or the like can also be used. As shown in FIG. 2, for example, the trigger pulse generator 112 is composed of a superconducting loop including an impedance modulator 111 and a Josephson element JJ ₁ .

Further, the superconducting single magnetic flux quantum generator 120
Is a portion that is generated or shaped (amplified) into a single magnetic flux quantum by the energy supplied from the external power source by using the pulse generated in the superconducting light guide detection unit 110 as a trigger, and for example, in the trigger pulse generation unit 112 described above. Josephson element JJ ₂ (... J connected in parallel with the superconducting loop
J _n ), and a superconducting loop including this Josephson device J
It is composed of an external power supply (Idc ₂ (... Idc _n )) that supplies energy to the magnetic flux generated in the portion J ₂ (... JJ _n ). A plurality of Josephson elements JJ ₂ (... JJ _n ) of the superconducting single-flux-quantum generating section 120 may be arranged according to the energy of the target single-flux-quantum, etc., and the plurality of Josephson elements JJ in that case. ₂ ... JJ _n are arranged such that the superconducting loops are connected in parallel.

In the superconducting light guide detector 110 shown in FIG.
When the optical signal p is applied to the impedance modulation section 111 that also functions as a light receiving section made of an oxide superconductor film or the like, the density of superconducting conductors changes due to an effect including a non-equilibrium phenomenon, and the impedance of this portion changes at an ultrahigh speed. . This means
It is also clear from the following report example. That is, YBa ₂ Cu ₃ O ₇ which is an oxide superconductor is processed into an H-shaped antenna pattern, and a constant current is applied between the tips of the left and right bars of the H-shaped femto in the middle horizontal bar. The results of observing electromagnetic radiation in the THz band as its optical response by applying an optical pulse have been reported (Tonai et al., IEICE Tech. S.
CE95-23, 13 (1995)).

[0025] by the above-mentioned impedance change, superconducting bias current Iotadc ₁ in the superconducting loop including a Josephson element JJ ₁ impedance modulation section 111
The diversion ratio of changes. Here, the superconducting light guide detection unit 110 shown in FIG. 3A will be described as an example. FIG. 3 (b)
Is an actual configuration example. Now, by irradiating the light pulse p, −
It is assumed that the instantaneous inductance L has increased (L (p)). Then, a lot of current flows into the Josephson element JJ ₁ ,
If the critical current Ι _c of this Josephson element JJ ₁ is designed to have an appropriate value, it will exceed Ι _c and will be in a voltage state for a moment to generate a voltage pulse. The time constant of the circuit should be designed short enough.

Of the magnetic flux generated in the Josephson element JJ ₁ at the same time as the voltage pulse (trigger pulse) described above, the upward magnetic flux generated in the superconducting single-flux quantum generator 120 side at the same time as the Josephson element JJ _1. Josephson devices JJ ₂ superconducting single flux quantum generator 120 which momentarily the voltage state transfers to (... JJ _n), Josephson devices JJ ₂ of the superconducting single flux quantum generator 120 (... JJ _n)
Bias current Ιdc ₂ (… Idc
_It receives energy from _n ) and grows and is shaped into a single magnetic flux quantum.

The Josephson element JJ ₀ is a resetting element after the trigger pulse and the single magnetic flux quantum are generated, and is used to release the unnecessary quantized magnetic flux generated for the next optical pulse. It is an element.

The optical pulse signal p can be modulated at high speed by direct modulation by a semiconductor laser, external modulation using an optical waveguide, traveling wave type external modulation, etc., as described above.
Since the irradiation of the optical pulse signal p to the generation of the single magnetic flux quantum is based on the ultra-high-speed impedance change in the impedance modulation unit 111, the ultra-high-speed modulation corresponding to the optical pulse signal p subjected to high-speed modulation is performed. A single flux quantum train can be obtained.

The single flux quantum train generated or shaped by the superconducting single flux quantum generating unit 120 and corresponding to the optical signal p is a superconducting single flux quantum logic in the subsequent stage of the superconducting light guide-single flux quantum conversion circuit 100. It is transferred to the circuit 200 and logically operated. That is, the superconducting single magnetic flux quantum logic circuit 200
An ultra-high-speed signal (single magnetic flux quantum train) commensurate with the calculation speed of
It is possible to input from the superconducting light guide-single magnetic flux quantum conversion circuit 100. Then, by integrating the superconducting light guide-single flux quantum conversion circuit 100 for a plurality of systems, it is possible to easily input super high speed signals of a large number of channels to the superconducting single flux quantum logic circuit 200. Superconducting single-flux quantum logic circuit 200 featuring arithmetic operation
It is possible to bring out the essential maximum performance of.

Next, a specific configuration example of the above-mentioned superconducting light guide-single magnetic flux quantum conversion circuit 100 will be described with reference to FIG. The superconducting light guide-single magnetic flux quantum conversion circuit 100 shown in FIG. 4 is manufactured by expanding the circuit shown in FIG. This superconducting light guide-single magnetic flux quantum conversion circuit 100
The superconductor film constituting the, YBa ₂ Cu ₃ O ₇ with film, also in each Josephson device YBa ₂ Cu ₃ O ₇ /
A ramp edge type junction of PrBa ₂ Cu ₃ O ₇ / YBa ₂ Cu ₃ O ₇ was used.

In FIG. 4, 11 is the above YBa ₂ Cu ₃
YBa ₂ Cu ₃ which is a superconducting bias line (Idc ₁ ) made of an O ₇ film and which serves as an impedance modulating section 14 which also functions as a light receiving section via the first and second Josephson elements 12 and 13 on the superconducting bias line 11. The O ₇ film is connected. By these, the superconducting light guide detection unit 11
A superconducting loop forming 0 is formed. here,
The first Josephson element 12 corresponds to the Josephson element JJ ₀₁ in FIG. 3, and the second Josephson element 13 corresponds to the Josephson element JJ ₁ .

Further, Y which becomes the impedance modulation section 14
A ground plane 15 is connected to the Ba ₂ Cu ₃ O ₇ film in order to suppress inductance. The YBa ₂ Cu ₃ O ₇ film that becomes the impedance modulation section 14 is
The film thickness is made thinner than the other parts, and the width is greatly expanded to further reduce the inductance.

YBa _{2 serving as the} impedance modulation section 14
The superconducting line 16 connected to the Cu ₃ O ₇ film is connected to the superconducting bias line 11 via the third Josephson element 17 corresponding to the Josephson element JJ ₂ in FIG. A superconducting loop which constitutes the superconducting single magnetic flux quantum generating part 120 is formed with the Josephson element 13. This superconducting loop is dc-SQUID1
Make up eight.

In the superconducting single-flux-quantum generating section 120, the bias current Idc _{2 is} supplied from the superconducting bias line 19.
Is supplied. In the figure, 20 is a superconducting contact.

The circuit configuration shown in FIG. 4 corresponds to n = 2 of the circuit configuration shown in FIG. The design of each partial inductance is the usual superconducting quantum interference device (SQUID)
Became the design of. After setting each bias, the optical pulse signal p was continuously irradiated through the optical fiber 21. Voltage V _dc of the case, by applying a bias current Ιdc ₃ dc-
When the current-voltage characteristics were measured while changing the magnetic flux of the SQUID 18, a Shapiro step was observed, and the frequency obtained from the current step interval was 5 GHz, which coincided with the optical pulse repetition frequency. This is shown in FIG. Therefore, it was confirmed that the optical signal was detected.

FIG. 6 shows a test circuit obtained by expanding FIG. 4 for further investigation. In this circuit, the single magnetic flux quantum generated by the optical pulse signal p is transferred to the superconducting transformer 22.
It is designed to be able to store on the primary side, and the stored magnetic flux can be detected by the dc-SQUID23 on the secondary side. FIG. 7 shows the measurement results. It can be seen that the output voltage of the dc-SQUID rises stepwise each time one optical pulse enters, and that a single magnetic flux quantum is sent. In these tests, problems such as external noise as in the case of the electric input method described above were not found.

Next, an embodiment of the second superconducting circuit of the present invention will be described.

8 to 10 are views showing an embodiment of the second superconducting circuit, which functions as a light receiving element for the optical signal p. Here, in order to prevent blunting of the input waveform due to the optical signal p and to eliminate the influence of light on the peripheral circuit parts such as the photodetection part, the photodetection part and the like should be separated from the superconducting light receiving part. Therefore, the optical response waveform of the superconducting light receiving section may be propagated without being distorted. Therefore, if the concept of the distributed constant circuit is adopted, it is sufficient to use a superconducting electromagnetic wave transmission line such as a superconducting microstrip line, and since this superconducting electromagnetic wave transmission line has a superconducting film, it is used as a light receiving part. can do.

The superconducting light receiving element shown in FIG. 8 has a superconducting electromagnetic wave transmission line 33 having a superconducting microstrip structure formed of superconducting films 31 and 32. A DC current Idc is supplied from a DC power source 34 to one of the superconducting film 31 constituting the superconducting electromagnetic wave transmission line 33, and a light receiving portion 35 is provided in a certain section of the superconducting film 31. One of the line ends of the superconducting electromagnetic wave transmission line 33 has a characteristic impedance Z of the superconducting electromagnetic wave transmission line 33.
Matching termination is performed with a load impedance 36 equal to ₀ , and the other line end serves as an output terminal 37.

When the optical signal p is applied to the superconductor film 31 corresponding to the above-mentioned light receiving portion 35, a voltage pulse is generated there. This pulse propagates toward both ends of the superconducting electromagnetic wave transmission line 33, but since one end is matched and terminated, it is possible to detect light by the pulse propagated to the output terminal 37 provided at the other end. You can At this time, due to the characteristics of the superconducting electromagnetic wave transmission line 33, the pulse waveform responding to the optical signal p can be taken out from the output terminal 37 with a certain delay. That is, the pulse waveform in response to the optical signal p can be taken out as a voltage change corresponding to the optical pulse, that is, a change in impedance, without significantly blunting the output terminal 37 at a proper distance from the light receiving unit 35. Becomes

Here, as the method of biasing the current to the superconductor film 31, it is also possible to adopt the method as shown in FIG. Also, as shown in FIG. 10, it is possible to provide a plurality of light receiving portions 35, apply light to the light receiving portions 35, 35 at the plurality of locations, perform an arithmetic operation with an electric signal, and provide a plurality of output terminals 37. is there. Further, it is possible to strengthen the pulse by applying light to a plurality of sections with an optical path difference.

FIG. 11 is a diagram showing another embodiment of the second superconducting circuit. As shown in the figure, the optical waveguide 38 which receives the optical pulse signal p modulated by the signal is arranged so as to be in contact with the superconducting film 31 constituting the superconducting electromagnetic wave transmission line 33, and the incident optical pulse LP is The superconductor film 31 is absorbed and attenuated in a distributed constant manner. Further, the optical waveguide 38
The speed of light inside and the speed of electromagnetic wave in the superconducting electromagnetic wave transmission line 33 are matched.

At this time, the current bias Idc similar to that in FIG. 8 is arranged so as to absorb light.
If is kept flowing, the voltage pulse VP corresponding to the input optical pulse LP is generated. This voltage pulse VP and light pulse
Due to the matching of the LP velocities, the light pulse LP decays as it proceeds to give energy to the voltage pulse VP, while the voltage pulse VP changes its impedance in that part due to the light pulse LP. As a result, energy is obtained from the current bias Idc, and the energy is increased as if the energy was obtained from the light pulse LP. The optical pulse LP is attenuated when it reaches the vicinity of the output terminal 37, and the voltage pulse VP appears at the output terminal 37 instead. In this way, a broadband light receiving element can be constructed.

Next, a specific structural example of the superconducting light receiving element shown in FIG. 8 will be described with reference to FIG. As a superconducting film forming this superconducting circuit, Y
A Ba ₂ Cu ₃ O ₇ film was used.

In FIG. 12, 41 is YBa ₂ Cu ₃ O
₇ (thickness = 10 nm) / CeO ₂ (thickness = 300 nm) / YBa ₂ C
It is a superconducting microstrip line having a laminated structure of u ₃ O ₇ (thickness = 300 nm), and has a characteristic impedance of the superconducting microstrip line 41 at one end thereof.
A terminating resistor 42 equal to (= 10Ω) is connected. Here, molybdenum is used for the termination resistor 42, and YBa
_At the interface between ₂ Cu ₃ O ₇ and molybdenum, Au with a thickness of 20 nm is used.
Is sandwiched between.

The other end of the superconducting microstrip line 41 serves as an output terminal 43. Here, in order to easily measure the output, the ramp edge Josephson junction 4 is connected to the output terminal 43 so that the output can be detected by DC.
4 connected. Light can be detected in a direct current manner by the Shapiro step appearing in the current-voltage characteristic of the Josephson junction 44. In addition, a superconducting bias line 46 that causes a direct current to flow from the DC power supply 45 to the superconducting microstrip line 41.
Has raised the characteristic impedance so that it does not affect high frequencies.

Regarding such a superconducting optical element, an intermediate portion (light receiving portion 47) of the superconducting microstrip line 41.
FIG. 13 shows the current-voltage characteristics of the Josephson element when the laser light modulated at 5 GHz is irradiated from the optical fiber 48. As is clear from FIG. 13, the Shapiro step corresponding to the frequency was observed and the operation was confirmed. Further, FIG. 14 shows a specific configuration example of the superconducting circuit shown in FIG. 11, in which Τi is diffused in a LiNbO ₃ substrate 51 to form an optical waveguide 52 having a length of 50 mm, and then the optical waveguide 52 and one of As shown in FIG. 12, the YBa ₂ Cu ₃ O ₇ film is contacted.
A superconducting microstrip line 41 similar to that was formed. The other parts have the same structure as in FIG.

In the light receiving element shown in FIG. 14, an optical signal is transmitted from the optical fiber 48 to the optical waveguide 52 by using the lens 53.
When the same test as the light receiving element shown in FIG. 12 was conducted, the operation was confirmed. In this method, the optical waveguide 52 can be placed in the superconducting electromagnetic wave transmission line.

[0049]

As described above, according to the first superconducting circuit of the present invention, it is possible to input data or the like at ultrahigh speed to an ultrahigh speed superconducting logic circuit using a single flux quantum. Is possible. As a result, it is possible to realize information processing or the like that sufficiently exhibits the ultra-high speed of the superconducting logic circuit or the like. Further, according to the second superconducting circuit, it becomes possible to convert the optical signal into an electric signal in a wide band while eliminating the influence of light on the peripheral circuits.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a superconducting logic circuit using the first superconducting circuit of the present invention as an input circuit.

FIG. 2 is a diagram showing a configuration example of a superconducting light guide-single magnetic flux quantum conversion circuit as one embodiment of a first superconducting circuit of the present invention.

FIG. 3 is a diagram showing a configuration of a superconducting light guide detection unit in the superconducting light guide-single magnetic flux quantum conversion circuit shown in FIG.

FIG. 4 is a diagram showing a specific configuration example of the superconducting light guide-single magnetic flux quantum conversion circuit shown in FIG.

5 is a diagram showing a result of performing photodetection by the superconducting light guide-single magnetic flux quantum conversion circuit shown in FIG.

6 is a diagram showing an integrated circuit produced by expanding the superconducting light guide-single magnetic flux quantum conversion circuit shown in FIG. 4;

FIG. 7 is a diagram showing a result of light detection performed by the superconducting light guide-single magnetic flux quantum conversion circuit shown in FIG.

FIG. 8 is a diagram showing a configuration of a superconducting light receiving element which is an embodiment of a second superconducting circuit of the present invention.

9 is a diagram showing a configuration of a modified example of the superconducting light receiving element shown in FIG.

FIG. 10 is a diagram showing a configuration of another modification of the superconducting light receiving element shown in FIG.

FIG. 11 is a diagram showing a configuration of a superconducting light receiving element as another embodiment of the second superconducting circuit of the present invention.

12 is a diagram showing a specific configuration example of the superconducting light receiving element shown in FIG.

13 is a diagram showing a result of detecting an optical signal by the superconducting light receiving element shown in FIG.

FIG. 14 is a diagram showing a specific configuration example of the superconducting light receiving element shown in FIG.

FIG. 15 is a block diagram showing an electrical input method to a conventional superconducting single-flux quantum logic circuit.

FIG. 16 is a block diagram showing an optical input method to a conventional superconducting single-flux quantum logic circuit.

[Explanation of symbols]

 100 ... Superconducting light guide-single magnetic flux quantum conversion circuit 110 ... Superconducting light guide detecting section 111 ... Impedance modulating section 112 ... Trigger pulse generating section 120 ... Superconducting single magnetic flux quantum generating section 33 ... Superconducting electromagnetic wave transmission line 35 ...... Light receiving part 37 …… Output terminal

Claims (2)

[Claims] 1. A superconducting light guide detection unit which is irradiated with an optical signal and generates a pulse by an impedance which changes by the irradiation of the optical signal, and a superconducting single magnetic flux quantum which generates or shapes a single magnetic flux quantum by using the pulse as a trigger. A superconducting circuit, comprising: a generator, and converting the optical signal into the single magnetic flux quantum. 2. A superconductor film forming a superconducting electromagnetic wave transmission line, comprising a light receiving portion provided at at least one or more places, and an output terminal provided at at least one line end of the superconducting electromagnetic wave transmission line. A superconducting circuit characterized by: