JP2931787B2 - Superconducting circuit - Google Patents

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 of an ultra-high-speed superconducting logic circuit.

[0002]

2. Description of the Related Art Magnetic flux quantized in units of a magnetic flux Φ ₀ (= 2.07 × 10 ⁻¹⁵ Wb) realized in an inductance loop in a superconducting circuit is defined as “1” / “1” / “None”. 0 ”
The RSFQ logic (RapidSingle Flux Quantum Lo
gic) and other logic circuits (eg, KK
Likharev et al., IEEE Trans.Appl.Supercond. Vol.
1, 3-28 (1991)). This kind of single flux quantum (Single
In a logic circuit using Flux Quantum, a pulse pulse whose pulse width corresponding to magnetic flux quantum can be generated using a Josephson element and whose pulse width is about ps (Φ ₀ when integrated over time, integrates the corresponding magnetic flux density in space) Even so, Φ ₀ is used.

[0003] The essential upper limit of the calculation speed of a logic circuit using quantized magnetic flux pulses is determined by the minimum time that can be separated in a circuit when the interval between the two pulses is reduced, and the magnetic flux quantum Φ ₀ is calculated as follows. It is expressed by a value obtained by dividing by the critical current / normal resistance product (Ι _c · R _n product) of the Josephson element (having no hysteresis on current-voltage characteristics) used in this circuit. For example, when the Ι _c · R _n product is 2 mV, it is possible to operate the integrated circuit at a frequency of 1 THz.
To date, examples have been reported in which a small RSFQ logic circuit was operated at a clock frequency of up to 370 GHz (BIBunyk et al., Appl. Phys. Lett., 66, 646 (199).
Five)).

Further, in a superconducting circuit, impedance matching between a wiring and an element can be easily realized, and the propagation delay is not limited by the CR time constant of the wiring as in an integrated circuit using semiconductor transistors. Since the propagation delay is determined by the time required for the signal to move 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 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 It is expected that the calculation speed will be realized.

FIG. 15 shows a circuit configuration in which a semiconductor circuit 1 as a room temperature device is input to a superconducting single flux quantum logic circuit 3 using a coaxial cable 2 or the like. In the case of a logic circuit that operates at a high speed of 1 THz, it is very difficult to directly input an ultra-high-speed signal corresponding to the high-speed operation from outside using the coaxial cable 2 or the like. This is because if the signal frequency becomes very 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 influence of stray impedance. In order to prevent reflection from occurring between the external high-impedance semiconductor circuit 1 and the superconducting logic circuit 3 and the coaxial cable 2 therebetween, a signal different from the original signal is input. This is because impedance matching and electromagnetic field mode matching need to be performed, and moreover, it is usually necessary to introduce a plurality of signal inputs.

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

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

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

[0010] Further, since one is light and the other is a single flux quantum (a voltage pulse of a fixed form in terms of an electric circuit),
Since it is not necessary to perform direct impedance matching or the like between the two and furthermore, it is not necessary to consider the floating impedance or the like in the signal introduction part to the superconducting single flux quantum logic circuit 3, so that the signal can be easily introduced. it can. Furthermore, as can be clearly understood from the consideration of introducing a signal into the optical-single-flux quantum conversion unit using an optical fiber, the influence of external electromagnetic noise (particularly low frequency noise) is reduced because a conductor is not used for a signal introduction cable. In addition, crosstalk hardly occurs even when a plurality of signal inputs are performed.

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

[0012]

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

As for the light receiving portion, when detecting a high-speed signal, it is necessary to arrange the light receiving portion immediately near the signal detecting portion in order to avoid dulling of the waveform due to the influence of the time constant. On the other hand, there is a problem that the light receiving portion cannot be brought close to the signal detecting portion because the influence of the light may reach the peripheral circuit portion made of the superconducting circuit due to the nature of light irradiation.

As described above, in order to sufficiently bring out the performance of a superconducting single flux quantum logic circuit or the like, it is important to improve the method of detecting an optical signal as an input signal. Specifically, it is possible to realize a signal input speed 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 dulling the input waveform. It has been an issue to make it possible to separate the light receiving unit from the signal detecting unit. 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 and the like. Enables the superconducting circuit to achieve a signal input speed that matches the operation speed of the superconducting single-flux quantum logic circuit, and eliminates the effects of light on peripheral circuits while preventing dull input waveforms. It is an object of the present invention to provide a superconducting circuit having the above configuration.

[0015]

First superconducting circuit in the present invention SUMMARY OF THE INVENTION comprises a superconductive film optical device signals is irradiated, Inpi <br/> of the superconductive film changes by the irradiation of the light signal A superconducting light detection unit that generates a pulse by
A superconducting single flux quantum generator having a Josephson element for generating or shaping the single flux quantum using the pulse as a trigger, wherein the optical signal is converted into the single flux quantum.

[0016] Further, the second superconducting circuit is described in claim 1.
In addition, one end of the superconducting circuit
With a superconducting film constituting a superconducting electromagnetic wave transmission line
And Bei, the light-receiving portion provided above at least one position of said superconducting electromagnetic wave transmission line superconductor film constituting the Mitsunobu
Signal is irradiated, and the other of the superconducting electromagnetic wave transmission line
The pulse is taken out from the output terminal provided at the end.
It is characterized in that that.

In the first superconducting circuit, light is irradiated to a superconducting film, a superconducting coupling, or a portion having superconductivity due to a proximity effect, and a pulse is generated by an impedance that changes at a very high speed in this portion. 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, the ultrahigh-speed single flux quantum train corresponding to the optical signal can be obtained because the ultrahigh-speed impedance change is based on the above.

In the second superconducting circuit, a light receiving portion provided on a part of the superconducting film constituting the superconducting electromagnetic wave transmission line is irradiated with light, thereby distorting a light response output waveform of the light receiving portion. Without this, it can be taken out from the output terminal which is separated from the light receiving section by an appropriate distance. Therefore, it is possible to arrange the detection unit at a position separated 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, where 100 is a superconducting light-single flux quantum conversion circuit, and 200 is a superconducting single flux quantum logic. Circuit.

The superconducting light-single flux quantum conversion circuit 100, which is one 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. And a superconducting single flux quantum generation unit 120 that generates or shapes a single flux quantum using the pulse as a trigger.

The superconducting light 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 irradiated optical signal p. This can be realized by an impedance modulating unit 111 made of a film and a trigger pulse generating unit 112 that generates a trigger pulse by an impedance change of the impedance modulating unit 111. As the impedance modulating unit 111, a grain boundary, a Josephson junction, or the like included in the oxide superconductor film can be used. Trigger pulse generating unit 112, for example, as shown in FIG. 2, constituted by a superconducting loop including a Josephson element JJ ₁ impedance modulation section 111.

The superconducting single flux quantum generator 120
Is a portion that is generated or shaped (amplified) into a single magnetic flux quantum by energy supplied from an external power supply, using a pulse generated by the above-described superconducting light detection unit 110 as a trigger. Josephson element JJ ₂ (... J connected in parallel with the superconducting loop
J _n ) and the Josephson element J
J ₂ constituted from an external power source and _{(Idc 2 (... Idc n)} ) for supplying energy to the magnetic flux generated in the portion of the (... JJ _n). A plurality of Josephson elements JJ ₂ (... JJ _n ) of the superconducting single magnetic flux quantum generating section 120 may be arranged in accordance with the energy of the target single magnetic flux quantum or the like. ₂ ... JJ _n are arranged so that each superconducting loop is connected in parallel.

In the superconducting light detecting section 110 shown in FIG.
When the optical signal p is applied to the impedance modulation section 111 which also functions as a light receiving section made of an oxide superconductor film or the like, the density of the superconductor changes due to an effect including a non-equilibrium phenomenon, and the impedance of this section changes at a very high speed. . This means
It is clear from the following report examples. That is, the oxide superconductor YBa ₂ Cu ₃ O ₇ is processed into an H-shaped antenna pattern, and a constant current is applied between the left and right rods of the H-shaped. It has been reported that THz-band electromagnetic radiation was observed as the optical response by applying a light pulse (Donouchi et al., IEICE Technical Report S
CE95-23, 13 (1995)).

The superconducting bias current Ιdc ₁ in the superconducting loop including the impedance modulating section 111 and the Josephson element JJ ₁ is generated by the impedance change described above.
Changes. Here, the superconducting light detection unit 110 shown in FIG. 3A will be described as an example. FIG. 3 (b)
Is an actual configuration example. Now, by irradiation of the light pulse p,-
It is assumed that the instantaneous inductance L increases (L (p)). Then, it flows into many current to the Josephson element JJ _1,
If the critical current Ι _c of the Josephson element JJ ₁ is designed to be an appropriate value, the voltage state exceeds the Ι _c for a moment and a voltage state is generated, and a voltage pulse is generated. The time constant of the circuit is designed to be sufficiently short.

Of the magnetic flux generated in the Josephson element JJ ₁ at the same time as the above-described voltage pulse (trigger pulse), the upward magnetic flux generated in the superconducting single magnetic flux quantum generating section 120 is the same as that of 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)
The bias current Ιdc ₂ (… Idc
It grows into a single flux quantum with energy from _n ) and is shaped.

The Josephson element JJ ₀ is a resetting element after generating a trigger pulse and a single magnetic flux quantum, and is used for releasing unnecessary quantized magnetic flux generated for the next optical pulse. Element.

As described above, the optical pulse signal p can be modulated at high speed by direct modulation using a semiconductor laser, external modulation using an optical waveguide, or traveling wave type external modulation.
Then, from the irradiation of such an optical pulse signal p to the generation of a single magnetic flux quantum, based on the ultra-high-speed impedance change in the impedance modulator 111, the ultra-high-speed corresponding to the optical pulse signal p modulated at a high speed is used. A single flux quantum train can be obtained.

The single flux quantum sequence corresponding to the optical signal p generated or shaped by the superconducting single flux quantum generator 120 is provided by the superconducting single flux quantum logic at the subsequent stage of the superconducting light-single flux quantum conversion circuit 100. The operation is transferred to the circuit 200 to perform a logical operation. That is, the superconducting single flux quantum logic circuit 200
Ultra-high-speed signal (single flux quantum train) matching the operation speed of
It becomes possible to input from the superconducting light-single flux quantum conversion circuit 100. By integrating the superconducting light-single flux quantum conversion circuit 100 into a plurality of systems, it is possible to easily input a multi-channel ultrahigh-speed signal to the superconducting single flux quantum logic circuit 200. Superconducting single flux quantum logic circuit 200 characterized by operation
It is possible to bring out the essential maximum performance.

Next, a specific configuration example of the above-described superconducting light-single flux quantum conversion circuit 100 will be described with reference to FIG. The superconducting light-single flux quantum conversion circuit 100 shown in FIG. 4 is obtained by expanding the circuit shown in FIG. This superconducting light-single flux quantum conversion circuit 100
YBa ₂ Cu ₃ O ₇ film is used for the superconductor film constituting the semiconductor device, and 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, reference numeral 11 denotes the above-mentioned YBa ₂ Cu ₃
A superconducting bias line (Idc ₁ ) made of an O ₇ film, and YBa ₂ Cu _{3 serving} as an impedance modulating unit 14 serving also as a light receiving unit via the first and second Josephson elements 12 and 13 to the superconducting bias line 11. The O ₇ film is connected. With these, the superconducting light detection unit 11
0 is formed in the superconducting loop. here,
First Josephson element 12 corresponds to a Josephson device JJ ₀₁ in FIG. 3, and the second Josephson element 13 corresponds to a Josephson device JJ _1.

Further, Y which becomes the impedance modulating unit 14
The ground plane 15 is connected to the Ba ₂ Cu ₃ O ₇ film in order to reduce the inductance. The YBa ₂ Cu ₃ O ₇ film serving as the impedance modulator 14 is
The film thickness is thinner than the other parts, and the width is greatly increased to further reduce the inductance.

YBa _{2 serving as the} impedance modulator 14
The superconducting line 16 connected to the Cu ₃ O ₇ film is connected to the superconducting bias line 11 via a third Josephson element 17 corresponding to the Josephson element JJ ₂ in FIG. A superconducting loop forming the superconducting single flux quantum generating section 120 is formed by the Josephson element 13. This superconducting loop is dc-SQUID1
8.

The superconducting single flux quantum generator 120 has a bias current Idc ₂ from the superconducting bias line 19.
Is supplied. In the figure, reference numeral 20 denotes a superconducting contact.

The circuit configuration shown in FIG. 4 corresponds to n = 2 in the circuit configuration shown in FIG. The design of each partial inductance is based on the usual superconducting quantum interference device (SQUID)
Following the design. 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 determined from the interval between the current steps was 5 GHz, which coincided with the repetition frequency of the light pulse. 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 more detailed examination. In this circuit, a single magnetic flux quantum generated by the optical pulse signal p is
The magnetic flux can be accumulated in the primary side, and the accumulated magnetic flux can be detected by the dc-SQUID 23 on the secondary side. FIG. 7 shows the measurement results. Each time one light pulse is applied, the output voltage of the dc-SQUID rises stepwise, indicating that a single flux quantum is being 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.

FIGS. 8 to 10 are diagrams showing an embodiment of the second superconducting circuit, which functions as a light receiving element of the optical signal p. Here, in order to prevent the input waveform from being dulled by the optical signal p and to eliminate the influence of light on peripheral circuit portions such as the photodetector, the photodetector must be separated from the superconducting light-receiving portion. In other words, it is only necessary to propagate the optical response waveform of the superconducting light receiving unit without distorting it. Therefore, if the concept of a distributed constant circuit is adopted, a superconducting magnetic wave transmission line such as a superconducting microstrip line may be used, and since this superconducting magnetic wave transmission line has a superconducting film, it is used as a light receiving portion. 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 passed from a DC power supply 34 to one of the superconducting films 31 constituting the superconducting magnetic wave transmission line 33, and a light receiving unit 35 is provided in a specific section of the superconducting film 31. One of the line ends of the superconducting magnetic wave transmission line 33 is the characteristic impedance Z of the superconducting magnetic wave transmission line 33.
It is matched and terminated with a load impedance 36 equal to ₀ , and the other line end is an output terminal 37.

When an optical signal p is applied to the superconductor film 31 corresponding to the light receiving section 35, a voltage pulse is generated there. Although this pulse propagates toward both ends of the superconducting electromagnetic wave transmission line 33, since one end is matched and terminated, light is detected by the pulse propagated to the output terminal 37 provided at the other end. Can be. At this time, a pulse waveform responding to the optical signal p can be extracted from the output terminal 37 with a certain time delay due to the characteristics of the superconducting magnetic wave transmission line 33. In other words, a pulse waveform in response to the optical signal p can be extracted as a voltage change corresponding to the optical pulse, that is, a change in impedance, without greatly dulling the output terminal 37 at an appropriate distance from the light receiving unit 35 on the way. Becomes

Here, as a method of biasing the current to the superconductor film 31, a method as shown in FIG. 9 can be adopted. Further, as shown in FIG. 10, a plurality of light receiving portions 35 may be provided, light may be applied to the plurality of light receiving portions 35, 35 to perform calculations using electric signals, or a plurality of output terminals 37 may be provided. is there. Furthermore, it is also possible to irradiate light to a plurality of sections with an optical path difference to strengthen the pulse.

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

At this time, a current bias Idc similar to that of FIG. 8 is applied to the superconductor film 31 arranged so as to absorb light.
, A voltage pulse VP corresponding to the input light pulse LP is generated. This voltage pulse VP and light pulse
Due to the matching of the speed of LP, the light pulse LP attenuates as it gives energy to the voltage pulse VP, while the voltage pulse VP changes the impedance of the part by the light pulse LP As a result, the energy is obtained from the current bias Idc and increases as if the energy was obtained from the light pulse LP. The light pulse LP attenuates by the time it reaches the vicinity of the output terminal 37, and a voltage pulse VP appears at the output terminal 37 instead. Thus, a broadband light receiving element can be configured.

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

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

The other end of the superconducting microstrip line 41 is an output terminal 43. Here, in order to facilitate the measurement of the output, a ramp edge Josephson junction 4 is connected to the output terminal 43 so that the output can be detected by DC.
4 was connected. DC light can be detected by the Shapiro step appearing in the current-voltage characteristics of the Josephson junction 44. A superconducting bias line 46 for passing a DC current from a DC power supply 45 to the superconducting microstrip line 41.
Increased the characteristic impedance so as not to affect high frequencies.

With respect to such a superconducting optical element, an intermediate portion (light receiving portion 47) of the superconducting microstrip line 41 is used.
FIG. 13 shows the current-voltage characteristics of the Josephson element when a laser beam modulated at 5 GHz is emitted from the optical fiber 48. As is clear from FIG. 13, Shapiro steps corresponding to the frequency were observed, and the operation was confirmed. FIG. 14 shows a specific configuration example of the superconducting circuit shown in FIG. 11, in which Δi is diffused into a LiNbO ₃ substrate 51 to form an optical waveguide 52 having a length of 50 mm. 12 so that the YBa ₂ Cu ₃ O ₇ film is in contact with the film.
A superconducting microstrip line 41 similar to the above was formed. The other parts were configured similarly to FIG.

In the light receiving element shown in FIG. 14, an optical signal is transmitted from an optical fiber 48 using a lens 53 to an optical waveguide 52.
Then, the same test as the light receiving element shown in FIG. 12 was performed, and 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 an ultra-high speed to an ultra-high-speed superconducting logic circuit or the like using a single flux quantum. Becomes possible. As a result, it is possible to realize information processing or the like that makes full use of the ultra-high speed of the superconducting logic circuit and the like. Further, according to the second superconducting circuit, it is possible to convert an optical signal into an electric signal in a wide band while eliminating the influence of light on peripheral circuits.

[Brief description of the drawings]

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

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

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

FIG. 4 is a diagram showing a specific configuration example of the superconducting light-single flux quantum conversion circuit shown in FIG. 2;

FIG. 5 is a diagram showing a result of light detection performed by the superconducting light-single flux quantum conversion circuit shown in FIG.

6 is a diagram showing an integrated circuit manufactured by expanding the superconducting light-single flux quantum conversion circuit shown in FIG.

FIG. 7 is a diagram showing a result of light detection performed by the superconducting light-single 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 the second superconducting circuit of the present invention.

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

FIG. 10 is a diagram showing a configuration of another modified example 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.

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 a conventional light input method to a superconducting single flux quantum logic circuit.

[Explanation of symbols]

 100 superconducting light-single magnetic flux quantum conversion circuit 110 superconducting light detecting unit 111 impedance modulating unit 112 trigger pulse generating unit 120 superconducting single magnetic flux quantum generating unit 33 superconducting electromagnetic wave transmission line 35 …… Light receiving part 37 …… Output terminal

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-7668 (JP, A) JP-A-7-15241 (JP, A) JP-A-9-55626 (JP, A) JP-A 64-64 88318 (JP, A) JP-A-7-335950 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 39/22 H01L 39/24 H01L 39/00 G01J 1/02 G01R 33/035

Claims (2)

(57) [Claims] 1. A has a superconductive film optical device signals is irradiated,
A superconducting light detecting section that generates a pulse by the impedance of the superconducting film that changes by irradiation of the optical signal, and a Josephson element that generates or shapes a single magnetic flux quantum by using the pulse as a trigger. A superconducting circuit comprising: a single flux quantum generator; and converting the optical signal into the single flux quantum. 2. A superconducting magnetic wave transmission according to claim 1 , wherein one end of the superconducting electromagnetic wave is matched and terminated.
Comprising a superconductor film constituting the line, the optical signal to the light receiving portion provided above at least one position of said superconducting electromagnetic wave transmission line superconductor film constituting the Tel
Isa is, and the superconducting circuit, wherein said that the pulses are taken from the output terminal provided at the other end of said superconducting electromagnetic wave transmission line.