JPS62102176A - Magnetic flux meter and superconductive accumulative operation circuit appropriate for the meter - Google Patents
Magnetic flux meter and superconductive accumulative operation circuit appropriate for the meterInfo
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- JPS62102176A JPS62102176A JP60241470A JP24147085A JPS62102176A JP S62102176 A JPS62102176 A JP S62102176A JP 60241470 A JP60241470 A JP 60241470A JP 24147085 A JP24147085 A JP 24147085A JP S62102176 A JPS62102176 A JP S62102176A
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- magnetic flux
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- quantum interference
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Abstract
Description
【発明の詳細な説明】
〔発明の利用公爵〕
本発明はジョセフソンデバイスを用いた磁束計およびそ
れに好適な超電導累積演算回路に関する。DETAILED DESCRIPTION OF THE INVENTION [Uses of the Invention] The present invention relates to a magnetometer using a Josephson device and a superconducting cumulative calculation circuit suitable therefor.
ジョセフソンデバイスを用いた磁束計は当技術分野では
公知であり、５ＱＵＩＤ磁束計に代表される。従来の５
ＱＵＩＤ磁束計は外界からの熱雑音や信号の増幅に使う
前置増幅器の雑音により５ＱＵＩＤが本来持つ感度を十
分に活用できなかった。この５ＱＵＩＤ磁束計の欠点を
補い、更に高感度の磁束計を実現するために、直流磁束
パラメトロン（ＤＣＦｌｕｘ Ｐａｒａｍｅｔｒｏｎ
；以下ＤＣＦＰと呼ぶ）回路を使う方法が提案されてい
る（特願昭６Ｏ−１２２５２６）。ＤＣＦＰ回路は磁束
に鋭敏で、高い回路利得を持っているため、磁束の比較
回路として優れた特性を持つ事ができる。この出願に記
載されている回路例では、磁束計は入力磁束と参照磁束
と比較する磁束比較回路と比較結果をもとに参照磁束を
更新する帰還回路から構成されている。この特許出願記
載の技術では ＤＣＦＰ回路から構成された磁束比較は
例えば液体ヘリウムの様な極低温環境に、積分又はアッ
プダウンカウンタから構成される帰還回路は従来技術で
は極低温デバイスで構成できなかったため室温環境で動
作するトランジスタ類で作られた。一般に極低温環境に
あるデバイスと室温環境にあるデバイスのを接続するた
めには長いケーブル線を必要とするが、このケーブルに
よる時間遅れが大きく、信号の伝送に長い時間がかった
。このため上記特許出願にかかる技術による。ＤＣＦＰ
回路を使った磁束計では測定周波数範囲を広げられない
ため高速の信号に追従できない欠点があった。また、長
い信号線に重畳する誘導雑音や室温に置かれた帰還回路
が原因とみられる熱雑音が測定系に混入するため、測定
精度や測定分解能を上げられない欠点があった。Magnetometers using Josephson devices are known in the art and are typified by the 5QUID magnetometer. Conventional 5
The QUID magnetometer could not fully utilize the inherent sensitivity of the 5QUID due to thermal noise from the outside world and noise from the preamplifier used to amplify the signal. In order to compensate for the shortcomings of this 5QUID magnetometer and realize a magnetometer with even higher sensitivity, we developed a DC flux parametron (DCFlux Parametron).
A method using a circuit (hereinafter referred to as DCFP) has been proposed (Japanese Patent Application No. 6O-122526). Since the DCFP circuit is sensitive to magnetic flux and has high circuit gain, it can have excellent characteristics as a magnetic flux comparison circuit. In the circuit example described in this application, the magnetometer includes a magnetic flux comparison circuit that compares the input magnetic flux with the reference magnetic flux, and a feedback circuit that updates the reference magnetic flux based on the comparison result. In the technology described in this patent application, the magnetic flux comparison composed of the DCFP circuit is operated in a cryogenic environment such as liquid helium, and the feedback circuit composed of an integral or up/down counter cannot be constructed with a cryogenic device in the conventional technology. It is made with transistors that operate at room temperature. Generally, long cables are required to connect devices in a cryogenic environment and devices in a room temperature environment, but the time delay caused by these cables is large and it takes a long time for signal transmission. For this reason, the technology related to the above patent application is used. DCFP
Magnetometers using circuits have the disadvantage of not being able to follow high-speed signals because the measurement frequency range cannot be expanded. In addition, inductive noise superimposed on long signal lines and thermal noise thought to be caused by feedback circuits placed at room temperature enter the measurement system, making it impossible to improve measurement accuracy and measurement resolution.
本発明の目的は測定周波数範囲が広く、高速の信号に追
従できる高感度、高分解能の磁束計およびそれに好適な
超伝導累積演算回路。The object of the present invention is to provide a high-sensitivity, high-resolution magnetometer that has a wide measurement frequency range and can follow high-speed signals, and a superconducting cumulative calculation circuit suitable for the same.
この目的を達成するために本発明では、帰還回路をジョ
セフソンデバイスで構成し超電導ループに循環電流をた
める方式の累積演算回路を採用した。この構成では磁束
比較回路と帰還回路の何れもが極低温環境中にあるため
上記特許出願に記載されている技術の欠点を一掃し、高
速、高感度の磁束計を実現できる。In order to achieve this objective, the present invention employs an accumulation calculation circuit in which the feedback circuit is configured with a Josephson device and a circulating current is accumulated in a superconducting loop. In this configuration, since both the magnetic flux comparison circuit and the feedback circuit are in an extremely low temperature environment, the drawbacks of the technology described in the above patent application can be eliminated, and a high-speed, high-sensitivity magnetometer can be realized.
以下、本発明を実施例を用いて詳細に説明する。 Hereinafter, the present invention will be explained in detail using Examples.
第２図は本発明で使う量子干渉素子の例である。FIG. 2 is an example of a quantum interference device used in the present invention.
第２ａ図にその等価回路を、第２ｂ図にそのシンボルを
示す、この量子干渉素子は２接合磁束結合量子干渉素子
と呼ばれる回路で、２個のジョセフソン接合１０．１１
と２個のインダクタ１２．１３からなる超電導ループ１
５から構成されている。この超電導ループの近傍には制
御線４が配置され、該制御線４に流れる制御電流により
発生する磁束は該超電導ループに鎖交し、該超電導ルー
プ１５に流れる最大超電導電流を制御する。該超電導ル
ープ１５には負荷抵抗１４が接続される。This quantum interference device, whose equivalent circuit is shown in Fig. 2a and its symbol is shown in Fig. 2b, is a circuit called a two-junction flux-coupled quantum interference device, and consists of two Josephson junctions.
Superconducting loop 1 consisting of and two inductors 12 and 13
It consists of 5. A control line 4 is placed near the superconducting loop, and the magnetic flux generated by the control current flowing through the control line 4 interlinks with the superconducting loop to control the maximum superconducting current flowing through the superconducting loop 15. A load resistor 14 is connected to the superconducting loop 15.
一般に該負荷抵抗１４の抵抗値を選択すれば、この量子
干渉素子の動作モード、すなわち該量子干渉素子の両端
に発生する電圧値、電圧波形等を変える事が出来る。Generally, by selecting the resistance value of the load resistor 14, it is possible to change the operating mode of the quantum interference device, that is, the voltage value, voltage waveform, etc. generated across the quantum interference device.
第３図は本発明で使う累積演算回路の原理構成図である
。この累積演算回路は該量子干渉素子１の両端に配線５
を介してインダクタ２を接続した超電導ループ７に直流
電流源３よりバイアス電流Ｉｇを供給した構成である。FIG. 3 is a diagram showing the basic configuration of the cumulative calculation circuit used in the present invention. This cumulative calculation circuit has wiring 5 at both ends of the quantum interference element 1.
In this configuration, a bias current Ig is supplied from a DC current source 3 to a superconducting loop 7 to which an inductor 2 is connected via a superconducting loop 7.
次に、第３図に示す累積演算回路の動作を説明する。例
えばインダクタンス２のインダクタンス値りが大きけれ
ば、累積演算回路の電源を投入した時点ではバイアス電
流Ｉｇはほとんど該量子干渉素子１に流れ、該インダク
タ２には流れない。この状態で該量子干渉素子１の制御
線４に制御電流を流すと該量子干渉素子１は電圧状態に
遷移し、該インダクタ２の両端には電圧ｖＬが発生する
。このためインダクタ２には該量子干渉素子１を循環経
路とする循環電流Ｉｃが流れるが、この循環電流Ｉｃは
（１）式％式％
ｒ ｃ ＝ −ｆ ＶＬｄ ｔ （１
）Ｌ
（１）かられかる様に、循環電流Ｉｃは該インダクタ２
の両端に発生する電圧の積分値すなわち累積値になって
いる。したがって制御信号線４に複数個のパルス信号が
印加された場合には、循環電流Ｉｃは入力さたれた信号
パルスの数に比例していることになり、第３図に示す回
路は制御線４に印加されるパルスの計数値すなわち累積
値を示すことになる。第３図に示す回路構成でき、該イ
ンダクタ２と該量子干渉素子１は超電導配線で接続され
ており、一つのループを構成しているため。Next, the operation of the cumulative calculation circuit shown in FIG. 3 will be explained. For example, if the inductance value of the inductance 2 is large, most of the bias current Ig flows to the quantum interference element 1 and does not flow to the inductor 2 at the time when the accumulator circuit is powered on. In this state, when a control current is passed through the control line 4 of the quantum interference device 1, the quantum interference device 1 changes to a voltage state, and a voltage vL is generated across the inductor 2. Therefore, a circulating current Ic flows through the inductor 2 with the quantum interference element 1 as a circulation path, and this circulating current Ic is expressed by the formula (1)% r c = -f VLd t (1
)L As seen from (1), the circulating current Ic is
It is the integrated value, that is, the cumulative value of the voltage generated across the terminal. Therefore, when a plurality of pulse signals are applied to the control signal line 4, the circulating current Ic is proportional to the number of input signal pulses, and the circuit shown in FIG. It shows the count value, that is, the cumulative value of the pulses applied to. The circuit configuration shown in FIG. 3 can be achieved because the inductor 2 and the quantum interference element 1 are connected by superconducting wiring and constitute one loop.
該インダクタ２の両端の電圧は該量子干渉素子１の電圧
に他ならない。該量子干渉素子ｌにはインダクタ２が負
荷として接続されているため、荷量子干渉素子１は一時
的に電圧状態に遷移しても定常状態では超電導状態にも
どることは明らか。しかし該量子干渉素子１が電圧状態
にある時に発生する電圧値、電圧波形は先にのべた負荷
抵抗１４の抵抗値による量子干渉素子の動作モードによ
り変化する。負荷抵抗１４の値が大きい場合は発生する
電圧は大きく、電圧状態の持続時間は長い。The voltage across the inductor 2 is nothing but the voltage of the quantum interference device 1. Since the inductor 2 is connected to the quantum interference element 1 as a load, it is clear that even if the charge quantum interference element 1 temporarily changes to a voltage state, it returns to the superconducting state in a steady state. However, the voltage value and voltage waveform generated when the quantum interference device 1 is in a voltage state change depending on the operation mode of the quantum interference device depending on the resistance value of the load resistor 14 described above. When the value of the load resistor 14 is large, the generated voltage is large and the duration of the voltage state is long.
一方負荷抵抗１４の抵抗値が小さいと発生する電圧値は
小さく、電圧状態の持続時間は短い。このため高速のパ
ルスに応答させるためには負荷抵抗１４の抵抗値を小さ
く選んだ方が有利である。On the other hand, when the resistance value of the load resistor 14 is small, the generated voltage value is small and the duration of the voltage state is short. Therefore, in order to respond to high-speed pulses, it is advantageous to select a small resistance value for the load resistor 14.
また測定電流の分解能を上げるためには負荷抵抗１４の
抵抗１４の抵抗値を小さく選んだ方が有利であることも
明らかである。しかし負荷抵抗１４ ゛の抵抗値を小
さく選んだ場合、１回の累積演算で得られる変化量は少
なく、累積値を大幅に変化させるには多くの時間を要す
る。この欠点を補うためには第４ａ図に示す累積加算回
路の変形回路を採用すればよい。第４ａ図に示す累積演
算１回路では超電導ループ回路７に２個の量子干渉素子
１．１′を挿入した構成である。この構成で例えば。It is also clear that it is advantageous to select a small resistance value for the load resistor 14 in order to increase the resolution of the measured current. However, if the resistance value of the load resistor 14' is selected to be small, the amount of change obtained by one cumulative calculation is small, and it takes a long time to significantly change the cumulative value. In order to compensate for this drawback, a modified circuit of the cumulative addition circuit shown in FIG. 4a may be employed. The single cumulative operation circuit shown in FIG. 4a has a configuration in which two quantum interference elements 1.1' are inserted into the superconducting loop circuit 7. For example with this configuration.
第１の量子干渉素子１の負荷抵抗１４の抵抗値を大きく
、第２の量子干渉素子１′の負荷抵抗１４の抵抗値を小
さくする。この構成では第１の量子干渉素子１の制御線
４に印加されるパルス信号により累積される循環電流Ｉ
ｃの値は小さく、第２の量子干渉素子１′に印加される
パルス信号により累積される循環電流Ｉｃの値は大きい
。従って、第４ａ図に示す回路構成で２個の量子干渉素
子ｌ。The resistance value of the load resistor 14 of the first quantum interference element 1 is increased, and the resistance value of the load resistor 14 of the second quantum interference element 1' is decreased. In this configuration, the circulating current I accumulated by the pulse signal applied to the control line 4 of the first quantum interference element 1
The value of c is small, and the value of the circulating current Ic accumulated by the pulse signal applied to the second quantum interference element 1' is large. Therefore, in the circuit configuration shown in FIG. 4a, two quantum interference elements l.
１′を使い分けて入力パルスを印加すれば、循環電流の
累積を最適な時間内に行う事が出来る。第４ａ図の例は
２個の量子干渉素子を使った場合であるが、他に２個以
上の量子干渉回路を用いて同様の動作を行う回路を構成
することも出来る。第４ｂ図は累積演算回路の他の変形
例で、加算と減算ができる累積演算回路の例である。第
４ｂ図の回路では第１の直流電流源３ａからバイアス電
流Ｉａを供給された第１の量子干渉素子１ａと第２の直
流電流源３ｂからバイアス電流Ｉｂを供給された第２の
量子干渉素子１ｂとインダクタ２で超電導ループ７を構
成している。この回路構成で第１の量子干渉素子１ａと
第２の量子干渉素子１ｂの発生する電圧の向きは該超電
導ループ７内で逆向きになる様に第１、第２の直流電流
源３ａ、３ｂの電流の方向を決める。従って第４ｂ図に
示す回路構成では、例えば第１の量子干渉素子１ａの制
御線４ａに入力されるパルス信号の数を加算し、第２の
量子干渉素子１ｂの制御線４ｂに入力されるパルス信号
の数を減算する累積演算回路を構成できる。If input pulses are applied while using 1', it is possible to accumulate the circulating current within an optimal time. Although the example in FIG. 4a uses two quantum interference devices, it is also possible to configure a circuit that performs the same operation using two or more quantum interference circuits. FIG. 4b shows another modification of the cumulative calculation circuit, and is an example of a cumulative calculation circuit that can perform addition and subtraction. In the circuit of FIG. 4b, a first quantum interference element 1a is supplied with a bias current Ia from a first DC current source 3a, and a second quantum interference element is supplied with a bias current Ib from a second DC current source 3b. 1b and the inductor 2 constitute a superconducting loop 7. With this circuit configuration, the first and second DC current sources 3a and 3b are arranged so that the directions of the voltages generated by the first quantum interference element 1a and the second quantum interference element 1b are opposite within the superconducting loop 7. determine the direction of the current. Therefore, in the circuit configuration shown in FIG. 4b, for example, the number of pulse signals input to the control line 4a of the first quantum interference element 1a is added, and the number of pulse signals input to the control line 4b of the second quantum interference element 1b is added. It is possible to configure an accumulation calculation circuit that subtracts the number of signals.
第４ｃ図はＤＣＦＰ回路の負荷線１０７に流れる電流の
向きを感知し、負荷電流工、を累積演算する回路である
。この回路では累積演算回路６００の動作を円滑に行な
うため第１．第２の量子干渉素子１ａ、ｌｂには第２の
制御線４ａ′。FIG. 4c shows a circuit that senses the direction of the current flowing through the load line 107 of the DCFP circuit and cumulatively calculates the load current. In this circuit, the first. A second control line 4a' is connected to the second quantum interference device 1a, lb.
４ｂ′、配線４０１、直流電流源４００を介してオフセ
ット電流工。が印加されてする。次にＤＣＦＰ回路５０
０の電流検出法と累積演算回路の動作について詳しく説
明する。第５図（ａ）。4b', wiring 401, offset current wire via DC current source 400; is applied. Next, the DCFP circuit 50
The zero current detection method and the operation of the cumulative calculation circuit will be explained in detail. Figure 5(a).
（ｂ）は２個の量子干渉素子１ａ、ｌｂの動作点を示し
た図で、（ａ）は第１の量子干渉素子１ａを、（ｂ）は
第２の量子干渉素子１ｂを表わしている。各々の図は磁
束結合形量子干渉素子のしきい値特性と呼ばれる特性図
で、量子干渉素子の超電導状態と電圧状態を区別する図
である。本発明の実施例では、量子干渉素子の２個のジ
ョセフソン接合１０．１１の最大超電導電流値、２個の
インダクタンス１２．１３のインダクタンス値を最適に
選んである。例えば、第１図に示す本発明の実施例では
、第１の量子干渉素子のしきい値特性は制御電流に対し
右上がりの、また第２の量子干渉素子のしきい値特性の
しきい値特性は制御電流に対し左上がりの特性になる様
に該ジョセフソン接合、該インダクタの特性を選んであ
る。量子干渉素子１ ａ、１ ｂにはバイアス電流Ｉｇ
ａ、Ｉｇｂが直流電流源３ａ、３ｂより供給されている
。第５図で、ＤＣＦＰ回路が励振されず、その出力電流
ＩＬが零の場合は２個の量子干渉素子１ａ、１ｂの動作
点は各々Ａ ａ ｒ Ａ ｂにあり、いずれも超電導状
態にある。このためこの時点では累積演算は実行されな
い、次にＤＣＦＰ回路が励振され、例えば正の向の出力
電流工、が流れれば各々の量子干渉素子の動作点はＢａ
、Ｂｂで表わされ、第１の量子干渉素子１ａは電圧状態
に遷移し、第２の量子干渉素子は超電導状態にある。こ
のため第４ａ図で説明したごとく、累積演算回路は加算
演算を実行する。同様にＤＣＦＰ回路５００の出力電流
の向きが負の場合は動作点は各々Ｃａ、Ｃｂになり、累
積演算回路６００は減算演算を行う。(b) is a diagram showing the operating points of two quantum interference devices 1a and lb, where (a) represents the first quantum interference device 1a, and (b) represents the second quantum interference device 1b. . Each figure is a characteristic diagram called the threshold characteristic of a flux-coupled quantum interference device, and is a diagram that distinguishes between a superconducting state and a voltage state of the quantum interference device. In the embodiment of the present invention, the maximum superconducting current value of the two Josephson junctions 10.11 and the inductance value of the two inductances 12.13 of the quantum interference device are optimally selected. For example, in the embodiment of the present invention shown in FIG. The characteristics of the Josephson junction and the inductor are selected so that the control current slopes upward to the left. A bias current Ig is applied to the quantum interference elements 1a and 1b.
a and Igb are supplied from DC current sources 3a and 3b. In FIG. 5, when the DCFP circuit is not excited and its output current IL is zero, the operating points of the two quantum interference elements 1a and 1b are respectively at A a r A b, and both are in a superconducting state. Therefore, no cumulative calculation is performed at this point.Next, when the DCFP circuit is excited and, for example, a positive output current flows, the operating point of each quantum interference element becomes Ba.
, Bb, the first quantum interference element 1a transitions to a voltage state, and the second quantum interference element is in a superconducting state. Therefore, as explained in FIG. 4a, the accumulation operation circuit performs an addition operation. Similarly, when the direction of the output current of the DCFP circuit 500 is negative, the operating points become Ca and Cb, respectively, and the cumulative calculation circuit 600 performs a subtraction calculation.
第１図は本発明による磁束計の実施例である。FIG. 1 shows an embodiment of a magnetometer according to the present invention.
第１図に示す磁束計は磁束を感知するピックアップコイ
ル２００とジョセフソン接合１００．１０１、励振イン
ダクタ１０３．１０４からなる超電導ループに負荷線１
０７を接続したＤＣＦＰ回路５００と、第１、第２の直
流電流源３ａ、３ｂ、第１．第２の量子干渉素子１ａ、
ｌｂ、インダクタ２からなる累積演算回路６００から構
成されている。ピックアップコイル２００で感知した磁
束信号はトランス２０２の巻線２０１と巻線１０８の磁
束結合を介してＤＣＦＰ回路５００に入力される。ＤＣ
ＦＰ回路５００は励振１０５を介して周期的に交流電流
１０６から供給される励振電流Ｉｅｘで励振される。Ｄ
ＣＦＰ回路５００の出力電流工りは入力信号の向きに拡
存して、該ＤＣＦＰ回路５００から接地に向けて流れる
場合（正の向き）と接地から該ＤＣＦＰ回路５００の超
電導ループに向けて流れる場合（負の向き）尼がある。The magnetometer shown in Fig. 1 has a load line 1 connected to a superconducting loop consisting of a pick-up coil 200 for sensing magnetic flux, a Josephson junction 100, 101, and an exciting inductor 103, 104.
07 is connected to the DCFP circuit 500, the first and second DC current sources 3a, 3b, the first . second quantum interference element 1a,
lb, and an accumulation calculation circuit 600 consisting of an inductor 2. The magnetic flux signal sensed by the pickup coil 200 is input to the DCFP circuit 500 via magnetic flux coupling between the winding 201 and the winding 108 of the transformer 202. D.C.
The FP circuit 500 is excited with an excitation current Iex periodically supplied from an alternating current 106 via an excitation 105 . D
The output current of the CFP circuit 500 expands in the direction of the input signal, and there are cases where it flows from the DCFP circuit 500 to the ground (positive direction) and cases where it flows from the ground to the superconducting loop of the DCFP circuit 500. (Negative) There is a nun.
ＤＣＦＰ回路５００の出力電流工、は負荷線１０７に流
れるが、この負荷線１０７は該第１、第２の量子干渉素
子１ａ、ｌｂの制御線４ａ。The output current of the DCFP circuit 500 flows into a load line 107, which is the control line 4a of the first and second quantum interference elements 1a and lb.
４ｂに接続されており、ＤＣＦＰ回路５００の電流はこ
れらの量子干渉素子１ａ、ｌｂで検知される。すなわち
量子干渉素子１ａ、ｌｂの制御線４ａ、４ｂに流れる制
御電流はＤＣＦＰ回路５００の出力電流ＩＬ他ならない
。累積演算回路６００はＤＣＦＰ回路５００の正または
負のパルス数を累積し、インダクタ２に流れる循環電流
Ｉｃとして情報を蓄える。この実施例ではインダクタ２
はトランス２０２の巻線であり、したがってトランス２
０２の巻線１０８を介して該循環電流Ｉｃの発生する磁
束を該ＤＣＦＰ回路５００は帰還する構成である。ここ
で循環電流Ｉｃによる磁束が負に帰還される様に、イン
ダクタ２の電流の向きを選んである。以上説明したごと
く第１図に示す磁束計ＤＣＦＰ回路５００の出力電流の
方向に対応して累積演算回路６００が加減算動作を行っ
てその結果を循環電流として蓄え、該循環電流の発生す
る磁束がピックアップコイル２００の感知した磁束と一
致した時点で平衡に達する帰還動作を行う。これらピッ
クアップコイル２００．ＤＣＦＰ回路５００、累積演算
回路６００および帰還回路系は全て液体ヘリウム中の様
な極低温環境下に置かれている。累積演算回路６００の
第１、第２の量子干渉素子１ａ、ｌｂの出力電圧は室温
中のアップダウンカウンタ３００に接続され、該累積演
算回路６００の累積値をモニタする。すなわちこのアッ
プダウンカウンタ３００は量子干渉素子１ａの出力パル
ス数を加算し、量子干渉素子１ｂの出力パルス数を減算
する動作を行い、このアップダウンカウンタ３００の出
力値は該循環電流工。4b, and the current of the DCFP circuit 500 is detected by these quantum interference elements 1a and lb. That is, the control current flowing through the control lines 4a and 4b of the quantum interference elements 1a and lb is nothing but the output current IL of the DCFP circuit 500. The accumulation calculation circuit 600 accumulates the number of positive or negative pulses of the DCFP circuit 500 and stores information as a circulating current Ic flowing through the inductor 2. In this example, inductor 2
is the winding of transformer 202, therefore transformer 2
The DCFP circuit 500 is configured to feed back the magnetic flux generated by the circulating current Ic through the winding 108 of 02. Here, the direction of the current in the inductor 2 is selected so that the magnetic flux due to the circulating current Ic is fed back negatively. As explained above, the cumulative calculation circuit 600 performs addition and subtraction operations in accordance with the direction of the output current of the magnetometer DCFP circuit 500 shown in FIG. 1, stores the result as a circulating current, and the magnetic flux generated by the circulating current is picked up. When the magnetic flux sensed by the coil 200 matches, a feedback operation is performed to reach equilibrium. These pickup coils 200. The DCFP circuit 500, the cumulative calculation circuit 600, and the feedback circuit system are all placed in an extremely low temperature environment such as in liquid helium. The output voltages of the first and second quantum interference elements 1a and lb of the cumulative calculation circuit 600 are connected to an up/down counter 300 at room temperature, and the cumulative value of the cumulative calculation circuit 600 is monitored. That is, this up/down counter 300 performs an operation of adding up the number of output pulses of the quantum interference device 1a and subtracting the number of output pulses of the quantum interference device 1b, and the output value of this up/down counter 300 is determined by the circulating current factor.
に比例する値となる。このアップダウンカウンタ以上説
明したごとく、本発明によればビックアツブコイル２０
０．ＤＣＦＰ回路５００、累積演算回路６００および帰
還回路系の磁束計の主要な部分をすべて極低温環境に置
く事ができるため、理想的な低雑音環境で動作する磁束
計を実現できる。このため高感度、高分解能の磁束計を
実現するために役立つ。また本発明に採用したＤＣＦＰ
回路、量子干渉素子はと高速スイッチング素子回路であ
るため高速の回路動作が可能であり、また帰還回路系が
コンパクトに集積化出来るので、測定周波数範囲の広い
、高速信号に追従出来る磁束計が実現するのに役立つ。The value is proportional to . As explained above, according to the present invention, this up/down counter
0. Since the main parts of the DCFP circuit 500, the cumulative calculation circuit 600, and the feedback circuit system of the magnetometer can all be placed in a cryogenic environment, it is possible to realize a magnetometer that operates in an ideal low-noise environment. Therefore, it is useful for realizing a high-sensitivity, high-resolution magnetometer. In addition, the DCFP adopted in the present invention
Since the circuit and quantum interference device are high-speed switching element circuits, high-speed circuit operation is possible, and the feedback circuit system can be integrated compactly, making it possible to create a magnetometer that can track high-speed signals with a wide measurement frequency range. Helpful.
本発明の詳細な説明する際に、累積演算回路の量子干渉
素子に２接合磁束結合量子干渉素子を使ったが、他に３
接合以上の磁束結合量子干渉素子を使える事は明らか。In the detailed explanation of the present invention, a two-junction flux-coupled quantum interference device was used as the quantum interference device of the cumulative calculation circuit, but three other
It is clear that a flux-coupled quantum interference device with more than just a junction can be used.
また実施例で、累積演算回路の循環電流をトランス２０
２を介して帰還したが、他にピックアップコイル２００
を介して帰還することも、ＤＣＦＰ回路に直接部、還で
きることも明らかである。In addition, in the embodiment, the circulating current of the cumulative calculation circuit is transferred to the transformer 20.
2, but there was also a pickup coil 200.
It is clear that it can be fed back via the DCFP circuit or directly to the DCFP circuit.
本発明によれば、高感度、高分解能で測定周波数範囲の
広い磁束計を実現できる。このため従来の磁束計では測
定出来なかった高速、微弱磁束の計測、例えば人体の脳
磁計測等ができる様になり、本発明の効果極めて大きい
。また、本発明による累積演算回路によれば、簡単に超
電導電流の累積を求めることができる。According to the present invention, a magnetometer with high sensitivity, high resolution, and a wide measurement frequency range can be realized. Therefore, it becomes possible to measure high-speed, weak magnetic flux that could not be measured with conventional magnetometers, such as measurement of brain magnetism in the human body, and the effects of the present invention are extremely large. Further, according to the accumulation calculation circuit according to the present invention, the accumulation of superconducting current can be easily obtained.
第１図は本発明による磁束計の実施例、第２図は本発明
で使う累積演算回路に使う２接合磁束結合量子干渉素子
、第３図は累積演算回路の原理構成図、第４図は累積演
算回路の変形回路例、第５図は本発明の実施例で使った
累積演算回路の動作を説明する図である。
１・・・量子干渉素子、２・・・インダクタ、３・・・
直流電流源、４・・・制御線、５・・・配線、７・・超
電導ループ、１０．１１・・・ジョセフソン接合、１２
．１３・・・インダクタ、１４・・・負荷抵抗、１５・
・・超電導ループ。
１００．１０１・・・ジョセフソン接合、１０３．１０
４・・・励振インダクタ、１０５・・・励振線。
１０６・・・交流電流源源、１０７・・・負荷線、１０
８．２０１・・・巻線、２００・・・ピックアップコイ
ル、２０２・・・トランス、３００・・・アップダウン
カウンタ、４００・・・直流電流源、４０１・・・配線
、５００・・・ＤＣＦＰ回路、６００・・・累積演算回
路。
第２画
（Ｌ）
ｃｂン第
（み）Fig. 1 shows an embodiment of the magnetometer according to the present invention, Fig. 2 shows a two-junction magnetic flux coupling quantum interference element used in the cumulative calculation circuit used in the present invention, Fig. 3 shows the principle configuration of the cumulative calculation circuit, and Fig. 4 shows the principle configuration of the cumulative calculation circuit. FIG. 5 is a diagram illustrating the operation of the cumulative calculation circuit used in the embodiment of the present invention. 1... Quantum interference element, 2... Inductor, 3...
DC current source, 4... Control line, 5... Wiring, 7... Superconducting loop, 10.11... Josephson junction, 12
．． 13...Inductor, 14...Load resistance, 15.
...Superconducting loop. 100.101...Josephson junction, 103.10
4... Excitation inductor, 105... Excitation line. 106... AC current source, 107... Load line, 10
8.201...Winding, 200...Pickup coil, 202...Transformer, 300...Up/down counter, 400...DC current source, 401...Wiring, 500...DCFP circuit , 600...cumulative calculation circuit. 2nd stroke (L)
cb nth (mi)
Claims (1)
生する第１の手段と、該差電流の大きさに応答して、数
がそれぞれ変化する正および負のパルスを出力する直流
磁束パラメトロン回路と、該正および負のパネルに応答
し、該正および負のパルスのそれぞれの累積の差に比例
した電流を該参照電流として出力する第２の手段とを有
する磁束計において、該第２の手段は該正又は負のパル
スに応答して、該累積差に比例した超電導循環電流を該
参照電流として該第１の手段に供給する手段を有するこ
とを特徴とする磁束計。 ２、特許請求範囲第１項に記載の磁束計において、該第
２の手段は、磁束結合量子干渉素子とインダクタからな
る、該循環電流を流す超電導ループを有し、該直流磁束
パラメトロン回路の出力電流が該磁束結合量子干渉素子
の制御電流となっていることを特徴とする磁束計。 ３、少なくとも１個のジョセフソン素子とインダクタか
らなる超電導ループと、該インダクタの両端に接続され
た直流電流供給手段と、該直流電流の一部を該超電導ル
ープに累算していくべきタイミングごとに、該ジョセフ
ソン素子を電圧状態にするパルスを供給する手段を有す
る超電導累積演算回路。 ４、特許請求範囲第３項に記載の超電導累積演算回路に
おいて、該超電導ループには第１、第２のジョセフソン
素子が含まれ、該第１、第２のジョセフソン素子の接続
点が接続され、該超電導ループのインダクタの両端には
該第１、第２の直流電源から極性が反対の直流電流が供
給され、該第１、第２のジョセフソン素子が電圧状態に
なるごとに極性の反対の電流を超電導ループに累積して
行く超電導累積演算回路。[Claims] 1. A first means for generating a difference current between a current proportional to the input magnetic flux and a reference current, and positive and negative currents whose numbers change, respectively, in response to the magnitude of the difference current. a DC magnetic flux parametron circuit for outputting pulses; and second means responsive to the positive and negative panels for outputting, as the reference current, a current proportional to the cumulative difference between each of the positive and negative pulses. In the magnetometer, the second means has means for supplying a superconducting circulating current proportional to the cumulative difference to the first means as the reference current in response to the positive or negative pulse. Magnetometer. 2. In the magnetometer according to claim 1, the second means has a superconducting loop for flowing the circulating current, which is composed of a magnetic flux coupling quantum interference element and an inductor, and the output of the DC magnetic flux parametron circuit A magnetometer, characterized in that the current serves as a control current for the flux-coupled quantum interference element. 3. A superconducting loop consisting of at least one Josephson element and an inductor, a direct current supply means connected to both ends of the inductor, and a timing at which a portion of the direct current is to be accumulated in the superconducting loop. a superconducting cumulative operation circuit having means for supplying a pulse to bring the Josephson element into a voltage state; 4. In the superconducting cumulative operation circuit according to claim 3, the superconducting loop includes first and second Josephson elements, and the connection point of the first and second Josephson elements is connected. DC currents of opposite polarity are supplied to both ends of the inductor of the superconducting loop from the first and second DC power sources, and the polarity changes each time the first and second Josephson elements enter the voltage state. A superconducting accumulation calculation circuit that accumulates opposite currents in a superconducting loop.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60241470A JPH0644034B2 (en) | 1985-10-30 | 1985-10-30 | Magnetic flux meter and superconducting cumulative arithmetic circuit suitable for it |
| CA000510927A CA1268815A (en) | 1985-06-07 | 1986-06-05 | Superconducting current detecting circuit employing dc flux parametron circuit |
| EP86107693A EP0205120B1 (en) | 1985-06-07 | 1986-06-05 | Superconducting current detecting circuit employing DC flux parametron circuit |
| DE3650062T DE3650062T2 (en) | 1985-06-07 | 1986-06-05 | Superconducting current sensor circuit. |
| US07/291,338 US4866373A (en) | 1985-06-07 | 1988-12-28 | Superconducting current detecting circuit employing DC flux parametron circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60241470A JPH0644034B2 (en) | 1985-10-30 | 1985-10-30 | Magnetic flux meter and superconducting cumulative arithmetic circuit suitable for it |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62102176A true JPS62102176A (en) | 1987-05-12 |
| JPH0644034B2 JPH0644034B2 (en) | 1994-06-08 |
Family
ID=17074789
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60241470A Expired - Lifetime JPH0644034B2 (en) | 1985-06-07 | 1985-10-30 | Magnetic flux meter and superconducting cumulative arithmetic circuit suitable for it |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0644034B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63290979A (en) * | 1987-05-22 | 1988-11-28 | Fujitsu Ltd | Superconducting quantum interference element |
| JPS6421379A (en) * | 1987-07-16 | 1989-01-24 | Fujitsu Ltd | Digital squid |
| US4947118A (en) * | 1988-11-21 | 1990-08-07 | Fujitsu Limited | Digital squid system adaptive for integrated circuit construction and having high accuracy |
-
1985
- 1985-10-30 JP JP60241470A patent/JPH0644034B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63290979A (en) * | 1987-05-22 | 1988-11-28 | Fujitsu Ltd | Superconducting quantum interference element |
| JPS6421379A (en) * | 1987-07-16 | 1989-01-24 | Fujitsu Ltd | Digital squid |
| US4947118A (en) * | 1988-11-21 | 1990-08-07 | Fujitsu Limited | Digital squid system adaptive for integrated circuit construction and having high accuracy |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0644034B2 (en) | 1994-06-08 |
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