JPH0558591B2 - - Google Patents
Info
- Publication number
- JPH0558591B2 JPH0558591B2 JP60128487A JP12848785A JPH0558591B2 JP H0558591 B2 JPH0558591 B2 JP H0558591B2 JP 60128487 A JP60128487 A JP 60128487A JP 12848785 A JP12848785 A JP 12848785A JP H0558591 B2 JPH0558591 B2 JP H0558591B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- current
- josephson
- vortex
- ground
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000010409 thin film Substances 0.000 claims description 89
- 230000005291 magnetic effect Effects 0.000 claims description 67
- 238000000034 method Methods 0.000 claims description 13
- 239000010408 film Substances 0.000 claims description 5
- 230000004907 flux Effects 0.000 description 24
- 230000000694 effects Effects 0.000 description 6
- 239000012528 membrane Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 230000007257 malfunction Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 239000002887 superconductor Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011423 initialization method Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N69/00—Integrated devices, or assemblies of multiple devices, comprising at least one superconducting element covered by group H10N60/00
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、ジヨセフソン集積回路及びジヨセフ
ソン集積回路内にトラツプ（捕捉）された磁束を
取り除くための初期化方法に関する。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to Josephson integrated circuits and initialization methods for removing magnetic flux trapped within Josephson integrated circuits.
（従来の技術及びその問題点）
ジヨセフソン集積回路は基板上に超伝導薄膜を
形成してなり、その超伝導薄膜は接地薄膜とこの
接地薄膜上に設けたジヨセフソン回路薄膜とから
なる。このジヨセフソン回路薄膜はジヨセフソン
接合、干渉計ループ、配線等からなつている。(Prior Art and its Problems) A Josephson integrated circuit is formed by forming a superconducting thin film on a substrate, and the superconducting thin film consists of a ground thin film and a Josephson circuit thin film provided on the ground thin film. This Josephson circuit thin film consists of Josephson junctions, interferometer loops, wiring, etc.
超伝導薄膜によつて作られるジヨセフソン集積
回路の正常動作をさまたげる障害のひとつとし
て、従来から超伝導薄膜における磁束のトラツプ
という現象が問題になつていた。臨界温度Tcを
もつ完全な超伝導薄膜の温度がＴ＞TcからＴ＜
Tcまで下がることにより、始め超伝導薄膜を貫
いていた磁場はマイスナー効果によつてすべて超
伝導薄膜から排除される。しかし、もしこの超伝
導薄膜の超伝導性が多少たりとも不純物、格子欠
陥などによつてそこなわれると、Ｔ＜Tcの状態
において磁場は超伝導膜内から完全には排出され
ず、トラツプされた磁束として薄膜内に残る。磁
場の十分弱い状態では、トラツプされる磁束はボ
ルテツクスとよばれる量子化された磁束である
（磁束量子Φ0＝２×10-7G／cm2）通常の方法で製
作される超伝導薄膜はいずれも完全なものではな
く、アイ・イー・イー・イー・トランズアクシヨ
ンズ・オン・マグネテイツク（IEEE
Transactions on Magnetics）Vol.MAG−19、
No.３、1983に述べられているような、磁束量子の
トラツプ現象が起きる事が知られている。実際の
ジヨセフソン集積回路は各ゲート間、ライン間の
磁気的結合を小さくするために接地薄膜上に作ら
れている。しかし、この接地薄膜内に磁束量子が
トラツプされていて（即ち、ボルテツクスが存在
して）、そしてそのトラツプされた磁束が干渉計
ループ又はジヨセフソン接合自身に結合している
とすると、ジヨセフソン集積回路は誤動作を起
す。第５図に上記のような状態を示す。 The phenomenon of magnetic flux traps in superconducting thin films has long been a problem that hinders the normal operation of Josephson integrated circuits made of superconducting thin films. The temperature of a perfect superconducting thin film with critical temperature Tc changes from T>Tc to T<
By lowering the temperature to Tc, the magnetic field that initially penetrated the superconducting thin film is completely removed from the superconducting thin film by the Meissner effect. However, if the superconductivity of this superconducting thin film is impaired to some extent by impurities, lattice defects, etc., the magnetic field will not be completely exhausted from within the superconducting film in the state of T<Tc, but will be trapped. The remaining magnetic flux remains within the thin film. When the magnetic field is sufficiently weak, the trapped magnetic flux is a quantized magnetic flux called vortex (magnetic flux quantum Φ 0 = 2×10 -7 G/cm 2 ). None of these are complete, and the IEEE
Transactions on Magnetics) Vol.MAG−19,
No. 3, 1983, it is known that a magnetic flux quantum trap phenomenon occurs. Actual Josephson integrated circuits are built on a grounded thin film to reduce magnetic coupling between each gate and between lines. However, if flux quanta are trapped in this grounded film (i.e., a vortex exists), and the trapped flux is coupled to the interferometer loop or the Josephson junction itself, then the Josephson integrated circuit Causes malfunction. FIG. 5 shows the above state.
第５図は磁束量子をトラツプした超伝導薄膜の
模式的な断面図である。図中、１は接地薄膜、２
は干渉計ループ、３はジヨセフソン接合、４はボ
ルテツクス（トラツプされた磁束量子）、５は磁
力線を示す。ボルテツクス４の径は約50nｍ、磁
場が貫ぬく接合の断面は約300nｍ×5000nｍ、干
渉計の径は約10000nｍ、膜厚はすべて約300nｍ
である。第５図のようにトラツプされた磁束が、
ジヨセフソン接合３と結合していると、その接合
３のジヨセフソン電流が小さくなるし、またそれ
が干渉計ループ２と結合していると干渉計ゲート
の制御特性に変化をもたらす。いずれの場合も磁
気的結合の度合によつてはその磁気的結合がゲー
トの誤動作を誘発する原因となる。通常ジヨセフ
ソン集積回路の動作は磁気遮蔽の中の非常に低い
磁場中で行なわれる。この種の磁気遮蔽内の磁場
は約10μGほどであるが、この磁場は例えば10cm
×10cmのチツプ総面積を持つ複数のジヨセフソン
集積回路チツプからなるジヨセフソンコンピユー
タ内に約5000個の磁束量子をトラツプさせコンピ
ユータの誤動作の原因となる。実際にはジヨセフ
ソンコンピユータを冷却する時に熱起電力によつ
て誘起される電流によつて、上記のようなサイズ
を持つコンピユータはさらに多くの（数万個乃至
数十万個の）磁束量子をトラツプするであろうと
推測されていて、このような環境下での正常な演
算動作はほとんど不可能である。 FIG. 5 is a schematic cross-sectional view of a superconducting thin film in which magnetic flux quanta are trapped. In the figure, 1 is a ground thin film, 2
is an interferometer loop, 3 is a Josephson junction, 4 is a vortex (trapped magnetic flux quantum), and 5 is a magnetic field line. The diameter of vortex 4 is approximately 50 nm, the cross section of the junction through which the magnetic field penetrates is approximately 300 nm x 5000 nm, the diameter of the interferometer is approximately 10000 nm, and the thickness of all films is approximately 300 nm.
It is. As shown in Figure 5, the trapped magnetic flux is
If it is coupled to Josephson junction 3, the Josephson current in that junction 3 will be small, and if it is coupled to interferometer loop 2, it will change the control characteristics of the interferometer gate. In either case, depending on the degree of magnetic coupling, the magnetic coupling may induce malfunction of the gate. Normally, Josephson integrated circuits operate in very low magnetic fields within a magnetic shield. The magnetic field within this type of magnetic shield is about 10 μG;
This traps about 5,000 magnetic flux quanta in the Josephson computer, which consists of multiple Josephson integrated circuit chips with a total chip area of 10cm x 10cm, causing the computer to malfunction. In reality, a computer with the above size can generate even more magnetic flux quanta (tens to hundreds of thousands) due to the current induced by thermoelectromotive force when cooling the Josephson computer. It is assumed that this will trap the data, and normal operation of the calculation under such an environment is almost impossible.
そこで、本発明の目的は、接地薄膜にトラツプ
された磁束による影響が避けられるジヨセフソン
集積回路及びその影響を取り除く方法を提供する
事にある。 SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a Josephson integrated circuit which avoids the effects of magnetic flux trapped in a ground thin film, and a method for eliminating the effects.
（問題点を解決するための手段）
前述の問題点を解決するために本願の第１の発
明が提供する手段は、超伝導薄膜が接地薄膜とこ
の接地薄膜上に設けられたジヨセフソン回路薄膜
とからなるジヨセフソン集積回路であつて、前記
接地薄膜の相対する縁辺にボルテツクス駆動電流
供給端子が設けてあることを特徴とする。(Means for Solving the Problems) In order to solve the above-mentioned problems, the first invention of the present application provides means in which the superconducting thin film is a ground thin film and a Josephson circuit thin film provided on the ground thin film. The Josephson integrated circuit is characterized in that vortex drive current supply terminals are provided on opposing edges of the ground thin film.
また、前述の問題点を解決するために本願の第
２の発明が提供する手段は、超伝導薄膜が接地薄
膜とこの接地薄膜上に設けられたジヨセフソン回
路薄膜とからなるジヨセフソン集積回路の初期化
方法であつて、前記接地薄膜は超伝導状態に保つ
たまま前記ジヨセフソン回路薄膜に第１の電流を
流してこのジヨセフソン回路薄膜を常伝導状態に
し、前記接地薄膜にこの膜の広平面に平行な方向
の直流又は脈流の第２の電流を流した後にこの第
２の電流を零にし、次に前記第１の電流を零にす
ることを特徴とする。 Further, in order to solve the above-mentioned problems, the second invention of the present application provides means for initializing a Josephson integrated circuit in which the superconducting thin film is composed of a grounded thin film and a Josephson circuit thin film provided on the grounded thin film. The method includes applying a first current to the Josephson circuit thin film while keeping the ground thin film in a superconducting state to bring the Josephson circuit thin film into a normal conducting state, and applying a current to the ground thin film parallel to a wide plane of the film. The method is characterized in that after a second current of direct current or pulsating current is passed in the direction, the second current is made zero, and then the first current is made zero.
（実施例）
次に実施例を挙げ本願発明を一層詳しく説明す
る。(Example) Next, the present invention will be described in more detail with reference to Examples.
第１図は本願の第１の発明の一実施例を示す模
式的な平面図、第２図は第１図実施例の模式的な
断面図である。以下に、これら図を参照して本願
の第１の発明の一実施例及び本願の第２の発明の
第１及び第２の実施例を説明する。 FIG. 1 is a schematic plan view showing an embodiment of the first invention of the present application, and FIG. 2 is a schematic cross-sectional view of the embodiment shown in FIG. An embodiment of the first invention of the present application and first and second embodiments of the second invention of the present application will be described below with reference to these figures.
図において、１〜５は第５図と同じものであ
り、６は接地薄膜１を流れる電流、７は電流６に
よりボルテツクスに加わるローレンツ力Ｆ（Ｆ＝
Ｊ×Φ0）、ここでＪは電流６の電流密度、Φ0は磁
束量子のベクトルである（Ｆ、Ｊ、Φ0はベクト
ル量である）。９は電流供給線、１０は電源、１
１はボルテツクス駆動電流供給端子である。ボル
テツクス駆動電流供給端子１１は接地薄膜１の相
対す縁辺に設けてあり、電流供給線９に接続して
ある。 In the figure, 1 to 5 are the same as in FIG. 5, 6 is the current flowing through the grounding thin film 1, and 7 is the Lorentz force F (F=
J×Φ 0 ), where J is the current density of the current 6 and Φ 0 is the vector of magnetic flux quanta (F, J, Φ 0 are vector quantities). 9 is a current supply line, 10 is a power supply, 1
1 is a vortex drive current supply terminal. The vortex drive current supply terminals 11 are provided on opposite edges of the ground thin film 1 and are connected to the current supply line 9.
第１図実施例にはボルテツクス駆動電流供給端
子１１が備えてあり、この端子から接地薄膜１に
電流６を流す事が可能になる。この電流６により
各ボルテツクス４に対して符号７で示すローレン
ツ力Ｆ＝Ｊ×Φ0が生じ、ボルテツクス４を接地
薄膜１の辺部へ追いやる事が出来る。電流密度Ｊ
にはそれにより接地薄膜１の表面に誘起される磁
界が接地薄膜１の臨界磁界Hc（もし材料が第２種
超伝導体ならば下部臨界磁界Hc1）を超えてはな
らないという上限があるので、ボルテツクス駆動
電流供給端子１１の数や形は出来るだけ均等な電
流分布が実現出来るように考慮して設計するのが
望ましい。 The embodiment shown in FIG. 1 is provided with a vortex drive current supply terminal 11 from which a current 6 can be passed through the ground thin film 1. This current 6 generates a Lorentz force F=J×Φ 0 indicated by 7 on each vortex 4, which can drive the vortex 4 to the side of the ground thin film 1. current density J
There is an upper limit that the magnetic field induced on the surface of the ground thin film 1 must not exceed the critical magnetic field Hc of the ground thin film 1 (lower critical magnetic field Hc 1 if the material is a type 2 superconductor). It is desirable that the number and shape of the vortex drive current supply terminals 11 be designed in such a way that a current distribution as uniform as possible can be realized.
なお、上記ボルテツクス駆動電流供給端子１１
は、トラツプされた磁束の影響を無くした初期化
後の本実施例の動作中には、接地薄膜１と実装基
板上の接地面とを電気的に接続する端子として機
能させることも可能である。 Note that the vortex drive current supply terminal 11
It is also possible to function as a terminal for electrically connecting the ground thin film 1 and the ground plane on the mounting board during operation of this embodiment after initialization to eliminate the influence of the trapped magnetic flux. .
本願の第２の発明は接地面内に存在するボルテ
ツクスがジヨセフソン集積回路に及ぼす影響を排
除する方法である。この第２の発明の第１の実施
例は以下の手順で行なわれる。まず超伝導状態に
ある超伝導薄膜において、干渉計ループ配線やジ
ヨセフソン接合を形成している上下電極や配線等
を構成するジヨセフソン回路薄膜に超伝導臨界電
流を超える第１の電流を流し、上記のジヨセフソ
ン回路薄膜を常伝導状態にする。次に電源１０か
ら直流の第２の電流６を接地薄膜１に流す。この
とき、第１図及び第２図で示されるようにローレ
ンツ力Ｆ＝Ｊ×Φ0がボルテツクス４にかかり、
ボルテツクス４を接地薄膜１内で電流６と垂直の
方向に移動させる。また、ボルテツクス４と逆方
向の磁束をトラツプしている反ボルテツクス４′
は第１図及び第２図で示されるようにボルテツク
ス４と正反対の方向に向かつて移動する。ジヨセ
フソン回路を構成している薄膜はすでに常伝導状
態に転移されているので、ボルテツクス４（以下
の説明では特に記す場合のほか反ボルテツクス
４′を含む）は接地薄膜１上部のジヨセフソン回
路薄膜からの磁気的抵抗をうけずにすみやかに接
地薄膜１内を移動出来る。この過程で注意するべ
きことは、電流６及び第１の電流によつて接地薄
膜１表面に誘起される磁界Ｈは決して接地薄膜１
を構成している材料の臨界磁界Hc（もし材料が第
２種超伝導ならば下部臨界磁界Hc1）を超えては
ならないことである。さもなければ新しいボルテ
ツクスが接地薄膜１に生じてしまう。したがつ
て、電流密度Ｊには上限JMaxが存在する。ボルテ
ツクスには通常ピン留め力FPという、磁束のト
ラツプされた位置からこれがほかに動かないよう
に現時点にとどめる力があるから、電流６を流し
作り出したローレンツ力ＦはＦ＞FPでなければ
ならない。 The second invention of the present application is a method for eliminating the influence of vortices existing in a ground plane on Josephson integrated circuits. The first embodiment of this second invention is carried out in the following steps. First, in a superconducting thin film in a superconducting state, a first current exceeding the superconducting critical current is passed through the Josephson circuit thin film that constitutes the upper and lower electrodes and wiring forming the interferometer loop wiring and the Josephson junction. The Josephson circuit thin film is brought into a normal conducting state. Next, a second DC current 6 is applied to the ground thin film 1 from the power source 10 . At this time, as shown in FIGS. 1 and 2, a Lorentz force F=J×Φ 0 is applied to the vortex 4,
A vortex 4 is moved within the ground membrane 1 in a direction perpendicular to the current 6. In addition, there is an anti-vortex 4' that traps the magnetic flux in the opposite direction to the vortex 4.
moves in the opposite direction to the vortex 4, as shown in FIGS. 1 and 2. Since the thin film constituting the Josephson circuit has already been transferred to a normal conduction state, the vortex 4 (in the following explanation, the anti-vortex 4' is included unless otherwise specified) is generated from the Josephson circuit thin film on top of the ground thin film 1. It can quickly move within the ground thin film 1 without being subjected to magnetic resistance. What should be noted in this process is that the magnetic field H induced on the surface of the ground thin film 1 by the current 6 and the first current never exceeds the ground thin film 1 surface.
must not exceed the critical magnetic field Hc of the material constituting the material (or the lower critical magnetic field Hc 1 if the material is a type II superconductor). Otherwise, new vortices would occur in the ground membrane 1. Therefore, the current density J has an upper limit J Max . Since a vortex normally has a pinning force F P that holds the magnetic flux at the current moment so that it does not move from the trapped position, the Lorentz force F created by flowing current 6 must be F > F P. It won't happen.
ボルテツクス４と反ボルテツクス４′はローレ
ンツ力にしたがつて移動し、第１図でしめされる
ように接地薄膜１の周辺部で磁気的反発力により
止まる。この状態で外部から加えられた第２の電
流６を零にする。電流６がなくなつてもボルテツ
クス４と反ボルテツクス４′はピン留め力FPによ
つて接地薄膜１の周辺部にピン留めされそこにと
どまる。次に第１の電流を零にする。これで超伝
導薄膜は通常の起伝導の動作状態になり、同時に
接地薄膜１のボルテツクスとジヨセフソン回路薄
膜とは磁気的には結合しなくなる。以上のような
過程を行なうことにより接地薄膜１内のボルテツ
クスの影響が排除出来る。更に加えて、最後の第
１の電流を零にする過程でジヨセフソン回路薄膜
が超伝導状態に移行する時に、外部磁界は以上説
明したように接地薄膜１の周辺部に集中している
ので、ジヨセフソン回路薄膜近辺の磁場は極めて
弱くジヨセフソン回路薄膜自体への磁束のトラツ
プも非常に起りにくい。 The vortex 4 and the anti-vortex 4' move according to the Lorentz force, and stop at the periphery of the ground thin film 1 due to magnetic repulsion, as shown in FIG. In this state, the second current 6 applied from the outside is made zero. Even when the current 6 is removed, the vortex 4 and anti-vortex 4' are pinned to the periphery of the ground membrane 1 by the pinning force F P and remain there. Next, the first current is made zero. The superconducting thin film is now in a normal conductive operating state, and at the same time the vortex of the ground thin film 1 and the Josephson circuit thin film are no longer magnetically coupled. By carrying out the above process, the influence of vortex within the ground thin film 1 can be eliminated. In addition, when the Josephson circuit thin film transitions to a superconducting state in the process of reducing the first and final current to zero, the external magnetic field is concentrated around the ground thin film 1 as explained above. The magnetic field near the circuit thin film is extremely weak, and trapping of magnetic flux into the Josephson circuit thin film itself is extremely unlikely.
次に本願の第２の発明の第２の実施例を説明す
る。前に述べたように、第２の電流６がボルテツ
クス４に及ぼすローレンツ力Ｆはピン留め力FP
より大きくなければならない。他方、第２の電流
６と第１の電流とにより接地薄膜１の表面に作ら
れる磁界Ｈは接地薄膜１の臨界磁界を超えてはな
らないから、第２の電流６の大きさには制限があ
る。そこで、FP＞｜FMnax｜＝｜JMnax×Φ0｜とい
うような大きいピン留めFPが働いている場合に
は前述の第１の実施例ではボルテツクスを移動す
る事は出来ない。ボルテツクスはピン留めセンタ
ー近傍で単振動を起す特性周波数を持つている。
この特性周波数はピン留め力とボルテツクスが超
伝導薄膜内を移動するときの摩擦力によつて決め
られていて、通常約0.1MHz〜50MHzぐらいであ
る。したがつて、この特性周波数でボルテツクス
を外部から駆動してやると、共振現象によりボル
テツクスはピン留めセンターから簡単にはずれ
る。つまりピン留め力FPが実効的にFP〜０とな
る。上記の理由で、直流電流に少量のボルテツク
スの特性周波数と同じ周波数の交流電流を重ねて
なる脈流を外部電源１０から流す事により、ボル
テツクスを簡単に移動させる事が出来る。この脈
流により接地薄膜１上に誘起される磁界は接地薄
膜１の臨界磁界以下でなくてはならない。このよ
うに、第２の実施例では第２の電流を脈流にして
ボルテツクスの移動を容易にした。その他は第１
の実施例と同様である。 Next, a second embodiment of the second invention of the present application will be described. As mentioned earlier, the Lorentz force F exerted by the second current 6 on the vortex 4 is the pinning force F P
Must be bigger. On the other hand, since the magnetic field H created on the surface of the ground thin film 1 by the second current 6 and the first current must not exceed the critical magnetic field of the ground thin film 1, there is no limit to the magnitude of the second current 6. be. Therefore, when a large pinning F P such as F P > |F Mnax |=|J Mnax ×Φ 0 | is in effect, the vortex cannot be moved in the first embodiment described above. Vortex has a characteristic frequency that causes simple harmonic motion near the pinning center.
This characteristic frequency is determined by the pinning force and the frictional force when the vortex moves through the superconducting thin film, and is usually around 0.1MHz to 50MHz. Therefore, if the vortex is driven externally at this characteristic frequency, the vortex will easily dislodge from the pinning center due to the resonance phenomenon. In other words, the pinning force F P effectively becomes F P ~0. For the above reasons, the vortex can be easily moved by supplying from the external power supply 10 a pulsating current made by superimposing a small amount of alternating current having the same frequency as the characteristic frequency of the vortex on a direct current. The magnetic field induced on the ground thin film 1 by this pulsating flow must be less than the critical magnetic field of the ground thin film 1. In this way, in the second embodiment, the second current is made into a pulsating flow to facilitate the movement of the vortex. Others are 1st
This is similar to the embodiment.
次に本願の第２の発明の第３の実施例を第３図
及び第４図を参照して説明する。第３図は本願の
第１の発明の前述の一実施例を示す模式的な平面
図であり、第１図と同様である。また、第４図は
その第３図の実施例の模式的な断面図であり、第
２図と同様である。但し、本願の第２の発明の第
３の実施例では、第３図及び第４図に符号８で示
すように、接地薄膜１の表面（広平面）に平行に
交流磁界Ｈを加える。この交流磁界Ｈの周波数は
ボルテツクス４の特性周波数とする。交流磁界Ｈ
は、第２の電流６を流している期間内にかける。
そして、第２の電流６は直流とする。このように
ボルテツクス４の特性周波数の交流磁界Ｈを接地
薄膜１にかけることにより、ボルテツクス４が共
振現象を起し、ボルテツクス４はピン留めセンタ
ーから簡単に外れる。すなわち、ピン留め力FP
が実効的に零になる。そこで、この第３の実施例
によれば、前述の第２の実施例と同様に、小さい
第２の電流でボルテツクス４を接地薄膜１の縁辺
へ追いやることができる。第２の電流６を流すの
に並行して交流磁界Ｈをかけること以外は前述の
第１の実施例と同様である。尚、本実施例でも、
接地薄膜１表面上の全磁界は接地薄膜１の臨界磁
界以下でなくてはならない。 Next, a third embodiment of the second invention of the present application will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic plan view showing the above-described embodiment of the first invention of the present application, and is similar to FIG. 1. 4 is a schematic cross-sectional view of the embodiment shown in FIG. 3, and is similar to FIG. 2. However, in the third embodiment of the second invention of the present application, as shown by reference numeral 8 in FIGS. 3 and 4, an alternating current magnetic field H is applied parallel to the surface (wide plane) of the ground thin film 1. The frequency of this alternating magnetic field H is assumed to be the characteristic frequency of the vortex 4. AC magnetic field H
is applied during the period when the second current 6 is flowing.
The second current 6 is a direct current. By applying an alternating magnetic field H having a characteristic frequency of the vortex 4 to the ground thin film 1 in this manner, the vortex 4 causes a resonance phenomenon, and the vortex 4 easily comes off the pinning center. That is, the pinning force F P
effectively becomes zero. Therefore, according to the third embodiment, the vortex 4 can be driven to the edge of the ground thin film 1 with a small second current, similar to the second embodiment described above. This embodiment is the same as the first embodiment described above, except that the alternating current magnetic field H is applied in parallel to the flow of the second current 6. In addition, in this example as well,
The total magnetic field on the surface of the ground thin film 1 must be less than the critical magnetic field of the ground thin film 1.
次に本願の第２の発明の第４の実施例を第３図
及び第４図を参照して説明する。この実施例で、
第２の電流６として脈流を流し、しかも接地薄膜
１の表面に平行な交流磁界Ｈをかける。その脈流
の脈動周波数と交流磁界Ｈの周波数は同じで、ボ
ルテツクスの特性周波数である。そして、脈流と
交流磁界Ｈとは同期している。このように、本実
施例では、第２の電流６の主要成分である直流の
他に、第２の電流６に交流成分を重畳して第２の
電流６を脈流とするとともに、この脈流を流して
いる期間内に交流磁界Ｈを加えている。そこで、
接地薄膜１内のボルテツクス４は、共振現象によ
りピン留めセンターから簡単に外れ、第２の電流
６との間のローレンツ力により接地薄膜１の縁辺
に追いやられる。第２の電流６に交流成分を含む
こと及び交流磁界Ｈをかけること以外は第１の実
施例と同様である。また、接地薄膜１の方面にお
ける全磁界が接地薄膜１の臨界磁界以下でなくて
はならないことは、他の実施例と同様である。 Next, a fourth embodiment of the second invention of the present application will be described with reference to FIGS. 3 and 4. In this example,
A pulsating current is passed as the second current 6, and an alternating current magnetic field H is applied parallel to the surface of the ground thin film 1. The pulsating frequency of the pulsating flow and the frequency of the alternating current magnetic field H are the same, which is the characteristic frequency of the vortex. The pulsating flow and the alternating current magnetic field H are synchronized. In this way, in this embodiment, in addition to the direct current that is the main component of the second current 6, an alternating current component is superimposed on the second current 6 to make the second current 6 a pulsating current. An alternating current magnetic field H is applied during the period when the current is flowing. Therefore,
The vortices 4 in the ground membrane 1 easily dislodge from the pinning center due to resonance phenomena and are driven to the edges of the ground membrane 1 by the Lorentz forces with the second current 6. This embodiment is the same as the first embodiment except that the second current 6 includes an alternating current component and that an alternating magnetic field H is applied. Also, as in the other embodiments, the total magnetic field in the direction of the ground thin film 1 must be less than the critical magnetic field of the ground thin film 1.
（発明の効果）
以上説明したように、本銀の第１の発明によれ
ば接地薄膜にトラツプされた磁束による影響が避
けられるジヨセフソン集積回路が提供でき、本願
の第２の発明によればその影響を取り除く方法が
提供できる。また、本願の第２の発明の方法で
は、ジヨセフソン回路薄膜が常伝導状態から超伝
導状態に転移する時に周辺の外部磁場が小さいの
で、ジヨセフソン回路薄膜には磁束トラツプが起
こりにくい。(Effects of the Invention) As explained above, according to the first invention of the present invention, a Josephson integrated circuit that can avoid the influence of magnetic flux trapped in the ground thin film can be provided, and according to the second invention of the present application, the Josephson integrated circuit can be provided. A method can be provided to remove the effects. Furthermore, in the method of the second invention of the present application, since the surrounding external magnetic field is small when the Josephson circuit thin film transitions from the normal conducting state to the superconducting state, magnetic flux traps are less likely to occur in the Josephson circuit thin film.
第１図及び第２図は本願の第１の発明の一実施
例を示す模式的な平面図及び断面図であるととも
に、本願の第２の発明の第１乃至第２の実施例を
説明する図である。第３図及び第４図は第１図に
示した本願の第１の発明の一実施例に適用する本
願の第２の発明の第３乃至第４の実施例を説明す
る図である。第５図は接地薄膜に磁束量子がトラ
ツプされている状態にあるジヨセフソン集積回路
の超伝導薄膜を示す模式的な断面図である。
１……接地薄膜、２……干渉計ループ、３……
ジヨセフソン接合、４……トラツプされた磁束
（ボルテツクス）、５……磁力線、６……接地薄膜
を流れる電流、７……ローレンツ力、８……交流
磁界、９……電流供給線、１０……電源、１１…
…ボルテツクス駆動電流供給端子。
FIG. 1 and FIG. 2 are a schematic plan view and a cross-sectional view showing an embodiment of the first invention of the present application, and also explain the first and second embodiments of the second invention of the present application. It is a diagram. 3 and 4 are diagrams for explaining third and fourth embodiments of the second invention of the present application, which are applied to the embodiment of the first invention of the present application shown in FIG. FIG. 5 is a schematic cross-sectional view showing a superconducting thin film of a Josephson integrated circuit in which magnetic flux quanta are trapped in a grounded thin film. 1...Ground thin film, 2...Interferometer loop, 3...
Josephson junction, 4... Trapped magnetic flux (vortex), 5... Lines of magnetic force, 6... Current flowing through the ground thin film, 7... Lorentz force, 8... Alternating magnetic field, 9... Current supply line, 10... Power supply, 11...
...Vortex drive current supply terminal.
Claims (1)
けられたジヨセフソン回路薄膜とからなるジヨセ
フソン集積回路において、前記接地薄膜の相対す
る縁辺にボルテツクス駆動電流供給端子が設けて
あることを特徴とするジヨセフソン集積回路。 ２ 超伝導薄膜が接地薄膜とこの接地薄膜上に設
けられたジヨセフソン回路薄膜とからなるジヨセ
フソン集積回路の初期化方法において、前記接地
薄膜は超伝導状態に保つたまま前記ジヨセフソン
回路薄膜に第１の電流を流してこのジヨセフソン
回路薄膜を常伝導状態にし、前記接地薄膜にこの
膜の広平面に平行な方向の直流又は脈流の第２の
電流を流した後にこの第２の電流を零にし、次に
前記第１の電流を零にすることを特徴とするジヨ
セフソン集積回路の初期化方法。 ３ 前記第２の電流を流す期間内に、前記広平面
に平行な方向の交流磁界を加えることを特徴とす
る特許請求の範囲第２項記載のジヨセフソン集積
回路の初期化方法。[Claims] 1. A Josephson integrated circuit in which the superconducting thin film is composed of a grounding thin film and a Josephson circuit thin film provided on the grounding thin film, in which vortex drive current supply terminals are provided on opposite edges of the grounding thin film. A Josephson integrated circuit characterized by: 2. In a method for initializing a Josephson integrated circuit in which the superconducting thin film comprises a grounding thin film and a Josephson circuit thin film provided on the grounding thin film, a first step is applied to the Josephson circuit thin film while the grounding thin film is maintained in a superconducting state. A current is passed through the Josephson circuit thin film to bring it into a normal conduction state, and a second current of direct current or pulsating current is passed through the ground thin film in a direction parallel to the wide plane of the film, and then the second current is made zero; A method for initializing a Josephson integrated circuit, the method comprising: setting the first current to zero; 3. The method for initializing a Josephson integrated circuit according to claim 2, characterized in that an alternating current magnetic field is applied in a direction parallel to the wide plane during the period in which the second current is applied.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60128487A JPS61287182A (en) | 1985-06-13 | 1985-06-13 | Josephson integrated circuit and initiating method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60128487A JPS61287182A (en) | 1985-06-13 | 1985-06-13 | Josephson integrated circuit and initiating method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61287182A JPS61287182A (en) | 1986-12-17 |
| JPH0558591B2 true JPH0558591B2 (en) | 1993-08-26 |
Family
ID=14985964
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60128487A Granted JPS61287182A (en) | 1985-06-13 | 1985-06-13 | Josephson integrated circuit and initiating method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61287182A (en) |
-
1985
- 1985-06-13 JP JP60128487A patent/JPS61287182A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61287182A (en) | 1986-12-17 |
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