JP4919051B2 - Superconducting qubit device and integrated circuit using the same - Google Patents

Description

  The present invention relates to a superconducting qubit device that can be used in a quantum computer, and more particularly to a superconducting qubit device including a qubit reading unit that can obtain a large signal and an integrated circuit using the same.

  Quantum computers can perform operations that cannot be performed by classical computers because states can be superimposed. Theoretically, a calculation with a plurality of inputs can be performed, and for this kind of calculation, the function of generating the superposition state is an indispensable function in the quantum computer.

  A qubit device is a component of a quantum computer. There are various types of this. For example, the qubit devices disclosed in Patent Documents 1 and 2 are devices called magnetic flux qubits and are superconducting loops having three Josephson junctions. The magnetic flux signal generated by the qubit device is read by a superconducting quantum interference device (DC-SQUID). Conventionally, a method of reading a magnetic flux signal by making a DC-SQUID close to a qubit element has been adopted.

  Non-Patent Document 1 reports that a DC-SQUID is made close to a qubit element and a qubit signal is observed. FIG. 5 is a diagram showing the critical current of the DC-SQUID reported in Non-Patent Document 1. In FIG. 5, the vertical axis represents the critical current of the DC-SQUID, and the horizontal axis represents the external magnetic flux applied to the qubit, which is proportional to the magnetic field applied from the outside. The inset shows the external magnetic flux in a wide range. When this part is enlarged, the qubit signal is observed as a small step.

JP 2005-260025 A JP 2005-302847 A Caspar H. van der Wal, A. C. J. ter Haar, F. K. Wilhelm, R. N. Schouten, C. J. P. M. Harmans, T. P. Orlando, Seth Lloyd and J.E. Mooij: Science, Vol. 290, pp. 773-777, 2000

  However, the method of reading a magnetic flux signal from a DC-SQUID formed close to a conventional qubit device has a problem that the obtained magnetic flux signal is weak because the mutual inductance between the qubit and the DC-SQUID is small. there were.

  In view of the above problems, an object of the present invention is to provide a superconducting qubit device capable of obtaining a large signal from the qubit device and an integrated circuit using the same.

In order to achieve the above object, a superconducting qubit device according to the present invention comprises a superconducting qubit unit and a qubit reading unit connected to the superconducting qubit unit, and the superconducting qubit unit comprises three Josephsons. A superconducting quantum interference device having a junction, and the qubit readout unit is composed of a superconducting quantum interference device having two Josephson junctions, and one of the Josephson junctions of the qubit readout unit is a superconducting quantum bit unit. It is configured to be shared with one of the Josephson junctions.
According to the above configuration, since the qubit readout unit is composed of a DC-SQUID that shares one of the Josephson junctions of the superconducting qubit unit, the magnetic flux signal generated in the superconducting qubit unit is highly sensitive. Can be detected.

In the above configuration, the superconducting qubit unit and the qubit reading unit are preferably formed of a loop-shaped thin line, and a thin line part in which a shared Josephson junction is formed among the thin lines is configured as a shared part. .
The magnetic flux in the loop of the qubit reading unit is preferably controlled to a value other than a half integer or an integral multiple of the magnetic flux quantum at the time of reading.
According to the above configuration, the mutual inductance between the superconducting qubit unit and the qubit reading unit can be increased, and the magnetic flux signal generated in the superconducting qubit unit can be detected with high sensitivity.

The integrated circuit of the present invention is composed of a plurality of superconducting qubit devices, each of which includes a superconducting qubit unit and a qubit reading unit connected to the superconducting qubit unit, The conduction qubit part is composed of a superconducting quantum interference element having three Josephson junctions, and the qubit reading part is composed of a superconducting quantum interference element having two Josephson junctions, and the Josephson junction of the qubit reading part Is configured so as to be shared with one of the Josephson junctions of the superconducting qubit portion.
In the above configuration, the superconducting qubit unit and the qubit reading unit are preferably formed of a loop-shaped thin line, and a thin line part in which a shared Josephson junction is formed among the thin lines is configured as a shared part. .
The magnetic flux in the loop of the qubit reading unit is preferably controlled to a value other than a half integer or an integral multiple of the magnetic flux quantum at the time of reading.
According to the above configuration, in the superconducting qubit device constituting the integrated circuit, the mutual inductance between the superconducting qubit unit and the qubit reading unit can be increased, and the magnetic flux signal generated in the superconducting qubit unit. Can be detected with high sensitivity.

In the above configuration, the magnetic flux transfer device is preferably disposed between adjacent superconducting qubit elements.
The control line is preferably arranged adjacent to the superconducting qubit section or adjacent to the magnetic flux transfer device.
According to the above configuration, the strength of coupling between two adjacent superconducting qubit devices can be arbitrarily controlled, and the superconducting qubit unit and the qubit reading unit of each superconducting qubit device can be controlled. The mutual inductance can be increased, and the magnetic flux signal generated in the superconducting qubit part can be detected with high sensitivity.

  According to the superconducting qubit device and the integrated circuit using the superconducting qubit device of the present invention, a sufficiently large magnetic flux signal can be obtained from the superconducting qubit device, so that the qubit signal is accurately read even in a noisy environment. be able to. Since a sufficient signal can be obtained even if the area of the qubit and the circulating current flowing are small, the quantum coherence time is the time for maintaining the quantum mechanical superposition state by reducing the area of the qubit and the circulating current flowing. There is a possibility that it can be extended more than before. Furthermore, since the number of necessary Josephson junctions can be reduced by one, manufacture becomes easy.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding members are denoted by the same reference numerals.
FIG. 1 is a plan view schematically showing a configuration of a superconducting qubit device 1 of the present invention. The superconducting qubit device 1 includes a superconducting qubit unit 2 made of a superconducting quantum interference device, and a qubit reading unit 3 connected to the superconducting qubit unit 2 and made of a superconducting quantum interference device. ing. The superconducting qubit device 1 of the present invention can be formed on a substrate.

  The superconducting qubit portion 2 is a superconducting quantum interference device formed by a thin wire portion 2a formed in a ring or a rectangle made of a superconductor and three Josephson junctions 2b, 2c, 2d. . Each Josephson junction 2b, 2c, 2d has a structure in which a thin insulating film that becomes a tunnel junction is sandwiched between thin wire portions 2a.

Here, Nb (niobium), Pb (lead), Al (aluminum), Sn (tin), In (indium), etc. are used as the superconductor material, and aluminum oxide (AlO _x ) is used as the insulating film. PbO or the like can be used.

  FIG. 2 is a partial cross-sectional view along the AA direction of the Josephson junction 2c shown in FIG. As shown in FIG. 2, the Josephson junction 2c includes a superconductor layer 11 formed on the insulating substrate 10, an insulating film 12 serving as a tunnel layer formed on the superconductor layer 11, and an insulating film. 12 and a superconductor layer 13 formed on the substrate 12. The thickness of the insulating film 12 serving as the tunnel layer is about 1 nm, for example. The other Josephson junctions 2b and 2d have the same structure.

  The qubit readout unit 3 connected to the superconducting qubit unit 2 includes a thin wire portion 3a formed in a ring or a rectangle made of a superconductor, and a Josephson junction 2d and a Josephson junction of the superconducting qubit unit 2. 3b and current terminals 3c and 3d provided at positions separated from these Josephson junctions 2d and 3b by about 90 °. A part of the left side of the thin wire portion 3 a is configured to be shared with the thin wire portion 2 aa of the superconducting qubit portion 2. That is, the thin wire portion 2aa is a common portion of the thin wire portion 3a. Therefore, the Josephson junction 2d of the qubit reading unit 3 and the Josephson junction 2d of the superconducting qubit unit are shared, that is, shared. The size of the ring of the thin wire portion 3a may be larger or smaller than the thin wire portion 2a of the superconducting qubit portion. In the present invention, the thin wires 2a and 3a having a ring or rectangular shape are collectively referred to as a loop-like thin wire, and an area determined by the shape of the ring or rectangle is referred to as a loop area.

  The Josephson junction 3a has a structure in which a thin insulating film that becomes a tunnel junction is sandwiched between thin wire portions 3a made of a superconductor material. That is, the qubit reading unit 3 is a so-called DC-SQUID (DC-superconducting quantum interference device). As for the dimensions of the thin wire portion 3a, the width can be about 200 nm and the thickness can be about 50 nm.

  The material of the superconductor and the insulating film used for the qubit readout unit 3 can be the same material as the superconducting qubit unit 2.

  As shown in FIG. 1, when the superconducting qubit unit 2 and the qubit reading unit 3 are, for example, thin line portions 2a and 3a each formed of a square, the dimension of one side of the qubit reading unit 3 is set to the qubit unit. It is longer than one side of the square, but may be shorter. In the superconducting qubit unit 2 and the qubit reading unit 3, the thin line portion 2aa serves as a common portion, and the mutual inductance increases.

The current that circulates through the thin wire portion 2a that forms the loop of the superconducting qubit portion 2 is reversed when the magnetic flux in the loop is a half-integer multiple of the magnetic flux quantum (1/2, 3/2, 5/2, etc.). Therefore, it behaves as a qubit when the magnetic flux in the loop is near a half integer multiple of the flux quantum.
On the other hand, when a qubit signal is read out by the DC-SQUID of the qubit reading unit 3, the magnetic flux in the loop formed by the thin wire portion 3a of the qubit reading unit 3 must not be a half integer or an integral multiple of the flux quantum. This is because the critical current of the DC-SQUID in this case is very insensitive to magnetic flux changes. Therefore, when the superconducting qubit device 1 is operated by applying a uniform magnetic field, the loop area of the qubit reading unit 3 must not be an integral multiple of the loop area of the superconducting qubit unit 2. However, if a control line for controlling the magnetic flux in the superconducting qubit unit 2 or the magnetic flux in the qubit reading unit 3 is provided, the above conditions regarding the area may not necessarily be satisfied.

  In a conventional superconducting qubit device represented by Non-Patent Document 1, the superconducting qubit part is formed in a DC-SQUID that is a qubit reading part. There is a constraint that the area is smaller than the area. Since the superconducting qubit unit 2 of the present invention is outside the qubit reading unit 3, the area of the superconducting qubit unit 2 may be smaller or larger than the qubit reading unit 3.

In the superconducting qubit device 1 of the present invention, in the DC-SQUID of the qubit reading unit 3, one Josephson junction 2 d is replaced with three Josephson junctions 2 b, 2 c, constituting the superconducting qubit unit 2. It has a configuration that is shared with one of 2d, that is, also used as one.
As a result, the Josephson inductance of the Josephson junctions 2b, 2c, 2d of the superconducting qubit unit 2 contributes to the mutual inductance with the qubit reading unit 3, so that the mutual inductance and qubit reading unit 3 The magnitude of the resulting magnetic flux signal can be significantly enhanced.

  Since the superconducting qubit device 1 can obtain a sufficient signal even if the area of the qubit and the circulating current flowing are small, the quantum coherence time can be extended as compared with the prior art by reducing the area of the qubit and the circulating current. May be possible.

  In the conventional qubit readout device, since the DC-SQUID is formed at a position away from the qubit, a total of five Josephson junctions are required, whereas the superconducting quantum of the present invention. Since the bit element 1 has one less Josephson junction than the conventional one, the manufacture is also easy.

Next, an integrated circuit using the superconducting qubit device 1 of the present invention will be described.
FIG. 3 is a schematic plan view showing an integrated circuit 20 comprising the superconducting qubit device of the present invention. The integrated circuit 20 includes a first superconducting qubit device 1, a second superconducting qubit device 15, and a magnetic flux transfer device 22 disposed between these superconducting qubit devices 1, 15; The first and second superconducting qubit devices 1 and 15 and the control lines 23, 24 and 25 are arranged close to the magnetic flux transfer unit 22, respectively. The superconducting qubit element 15 is the same element as the superconducting qubit element 1, and the corresponding parts are denoted by the same reference numerals. The integrated circuit 20 may include a plurality of sets, with the above-described configuration including the superconducting qubit elements 1 and 15 and the magnetic flux transfer device 22 as one set.

  The magnetic flux transfer unit 22 includes a magnetic flux transfer unit 22a and a superconducting quantum interference device unit 22b. The magnetic flux transfer part 22a is formed from a thin wire of a substantially rectangular superconductor. The superconducting quantum interference element portion 22b is formed by a thin line made of a rectangular superconductor. The lower side of the superconducting quantum interference device part 22b is shared with a part of the upper side of the magnetic flux transfer part 22a.

  The dimensions of the thin wires of the magnetic flux transfer unit 22a and the superconducting quantum interference device unit 22b can be about 200 nm in width and about 50 nm in thickness. As an example, the size of the magnetic flux transfer unit 22a can be about 4 μm × 10 μm. As an example, the rectangular superconducting quantum interference device portion 22b can be about 3 μm × 3 μm. Josephson junctions 22c and 22d are formed at the central part of the upper and lower long sides of the superconducting quantum interference element 22b. The superconducting quantum interference element 22b is a so-called DC-SQUID. The thickness of the DC-SQUID tunnel insulating film may be about 1 nm.

  In the case of FIG. 3, the left and right short sides of the magnetic flux transfer unit 22 a are arranged so as to face the Josephson junction 2 b of the superconducting qubit unit 2 in the first and second superconducting quantum interference devices 1 and 15. An example has been shown. The Josephson junction 2b of the superconducting qubit unit 2 may not be disposed on the left and right short sides of the magnetic flux transfer unit 22a. For example, the Josephson junction 2b can be disposed so as to face the Josephson junction 2c.

  The control line 23 arranged adjacent to the first superconducting qubit device 1 has a straight line part 23a parallel to the lower side of the superconducting qubit part 2 and perpendicular to both ends of the straight line part 23a. It is comprised from the vertical parts 23b and 23c extended so that it might bend. The lower ends of the vertical portions 23b and 23c are connected to a current source (not shown). The straight line portion 23 a is electromagnetically coupled to the superconducting qubit portion 2. That is, mutual inductance is generated between the control line 23 and the superconducting qubit unit 2. Thereby, a magnetic field is generated by applying a current to the control line 23, and the state of the superconducting qubit unit 2 in the first superconducting qubit device 1 can be controlled by this magnetic field.

  The control line 24 arranged adjacent to the second superconducting qubit element 15 has a straight line portion 24a parallel to the lower side of the superconducting qubit portion 2, and at both ends of the straight line portion 24a. It is comprised from the vertical parts 24b and 24c extended so that it might be bent vertically. The lower ends of the vertical portions 24b and 24c are connected to a current source (not shown). The straight line portion 24 a is electromagnetically coupled to the superconducting qubit portion 2. That is, mutual inductance is generated between the control line 24 and the superconducting qubit unit 2. Thereby, a magnetic field is generated by applying a current to the control line 24, and the state of the superconducting qubit unit 2 in the second superconducting qubit device 15 can be controlled by this magnetic field.

  The control line 25 disposed adjacent to the magnetic flux transfer unit 22 is adjacent to the upper side of the superconducting quantum interference element unit 22b, and is arranged at both ends of the linear unit 25a and parallel to the upper side. It is comprised from the vertical parts 25b and 25c extended so that it might be bent vertically. The upper ends of the vertical portions 25b and 25c are connected to a current source (not shown). The straight line portion 25a is electromagnetically coupled to the superconducting quantum interference device portion 22b. In other words, mutual inductance is generated between the control line 25 and the superconducting quantum interference element portion 22b. Thereby, a magnetic field is generated by applying a current to the control line 25, and the state of the superconducting quantum interference element unit 22 b in the magnetic flux transfer device 22 can be controlled by this magnetic field.

  The control lines 23, 24 and 25 are made of a material such as aluminum, and the dimensions thereof can be about 200 nm in width and about 50 nm in thickness.

In the magnetic flux transfer device 22, when the magnetic flux penetrating the superconducting quantum interference device unit 22b is set to a value that is an integral multiple of the magnetic flux quantum Φ ₀ , the first superconducting quantum interference device 1 and the second superconducting quantum interference device 15 A bond can be formed. That is, the coupling state between the first and second superconducting quantum interference elements 1 and 15 is turned on. The flux quantum Φ ₀ is expressed by the following equation (1).
Φ ₀ = h / (2e) (1)
Here, h is a Planck constant (6.626 × 10 ⁻³⁴ J · s), and e is a unit charge of electrons (1.602 × 10 ⁻¹⁹ C).

On the other hand, in the flux transfer unit 22, when the magnetic flux penetrating the SQUID portion 22b to half an odd multiple of the flux quantum [Phi _0, the first superconducting quantum interference device 1 second superconducting quantum interference device 15 can be eliminated. That is, the coupling state between the first and second superconducting quantum interference elements 1 and 15 is turned off.

According to the integrated circuit 20 including the superconducting qubit devices 1 and 15 of the present invention, the magnetic flux passing through the superconducting quantum interference device portion 22b is adjusted to the magnetic flux quantum Φ by adjusting the current flowing through the control line 25 in the magnetic flux transfer device 22. The strength of the coupling between the first superconducting quantum interference device 1 and the second superconducting quantum interference device 15 is arbitrarily controlled by setting it to an arbitrary value between half-odd multiple of _{0 and} an integral multiple. can do.

  In a similar manner, an integrated circuit composed of three or more superconducting qubit devices can be formed, and the strength of coupling between any two superconducting qubit devices in the integrated circuit is arbitrarily controlled. be able to. Since it is known that an arbitrary quantum calculation can be executed by using an integrated circuit having such characteristics, a quantum computer can be realized in principle.

According to the integrated circuit 20 including the superconducting qubit devices 1 and 15 of the present invention, one Josephson junction 2d of each qubit reading unit 3 of the superconducting qubit devices 1 and 15 is connected to the superconducting qubit unit. 2 has a configuration shared by one of the three Josephson junctions 2b, 2c, 2d.
As a result, the Josephson inductances of the Josephson junctions 2b, 2c, and 2d of the superconducting qubit unit 2 contribute to the mutual inductance with the qubit readout unit 3, so that the mutual inductance and the magnitude of the obtained magnetic flux signal are increased. Can be significantly enhanced.

  In the superconducting qubit devices 1 and 15, a sufficient signal can be obtained even if the area of the qubit and the circulating current flowing are small, so that the quantum coherence time can be reduced by reducing the area of the qubit and the circulating current flowing. There is a possibility that the length can be increased.

  In the conventional qubit readout device, since the DC-SQUID is formed adjacent to a position away from the qubit, a total of five Josephson junctions are necessary. Since the superconducting qubit device 1 has one less Josephson junction than the conventional one, it is easy to manufacture.

The case where the Josephson junction 2c shown in FIG. 2 is used as the superconducting qubit device 1 having the above configuration will be described.
As shown in FIG. 2, a superconductor layer 11 having a predetermined thickness is deposited on a Si (silicon) substrate 10 having an insulating substrate or a thermal oxide film by sputtering or the like, and shown in FIG. A part of the thin wire portions 2a and 3a of the superconducting qubit portion 2 and the qubit reading portion 3 is formed by selective etching using a mask.

  Next, an insulator material such as an alumina oxide film that becomes an insulating film having a predetermined thickness is deposited on the superconductor layer 11 by sputtering or CVD, and the excess insulator is removed by selective etching. A tunnel insulating film 12 is formed.

  Finally, a superconductor layer having a predetermined thickness is deposited on the tunnel insulating film 12 by sputtering, CVD, or the like, and the superconductor layer 13 is formed by removing the excess superconductor layer by selective etching. By doing so, the Josephson junction 2c can be manufactured. Similarly, the superconducting qubit device 1 and the integrated circuit 20 can be manufactured.

  Here, for the deposition of each material, an ordinary thin film forming method such as an evaporation method, a laser ablation method, or an MBE method can be used in addition to the sputtering method and the CVD method. Moreover, light exposure, electron beam (EB) exposure, etc. can be used for the mask process for forming the junction of a predetermined shape and a current terminal.

Next, based on an Example, this invention is demonstrated further in detail.
As an example, the superconducting qubit device 1 shown in FIG. 1 was manufactured using an electron beam exposure apparatus or the like. The thin wire portion 2a of the superconducting qubit portion 2 is a square having a side of 4 μm, and the thin wire portion 3a of the qubit reading portion 3 is a square having a side of 5 μm. The thin wire portions 2a and 3a have a line width of about 200 nm and a thickness of about 50 nm. Aluminum was used as a material for the superconductor to be the thin wire portions 2a and 3a. The insulating film used for each Josephson junction 2b, 2c, 2d, 3b was aluminum oxide, and its thickness was about 1 nm. The shape of each Josephson junction 2b, 2c, 2d, 3b was a rectangle of about 400 nm × 100 nm.

The critical current of the qubit reading unit 3 of the superconducting qubit device 1 manufactured in the example was measured.
FIG. 4 is a diagram illustrating the critical current of the DC-SQUID in the qubit reading unit 3 of the embodiment. In the figure, the vertical axis represents the statistical average value (nA) of the critical current, and the horizontal axis represents the current (mA) passed through the electromagnet for applying the magnetic field, which is proportional to the magnetic field applied from the outside.
As is clear from FIG. 4, in the embodiment, the critical current measured by the DC-SQUID of the qubit reading unit 3 is bent twice near the center (see arrows A and B in FIG. 4). This change in part is due to the magnetic flux signal of the qubit. The vibration waveform other than this part represents the characteristic of a normal DC-SQUID that the critical current of the DC-SQUID is vibrated by a magnetic field, similar to that shown in FIG. 5 (see Non-Patent Document 1).

  The magnitude of the magnetic flux signal by the superconducting qubit device 1 of the embodiment is about 60 times that of the non-patent document 1 shown in FIG. 5, and a smooth waveform with very little variation is obtained. I understand that.

  The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these are also included in the scope of the present invention. Nor.

It is a top view which shows typically the structure of the superconducting qubit element of this invention. It is a fragmentary sectional view in alignment with the AA direction of the Josephson junction shown in FIG. It is a typical top view which shows the integrated circuit which consists of a superconducting qubit element of this invention. It is a figure which shows the critical current of DC-SQUID in the qubit reading part of an Example. It is a figure which shows the critical current of DC-SQUID reported by the nonpatent literature 1. FIG.

Explanation of symbols

1: Superconducting qubit device (first superconducting qubit device)
2: Superconducting qubit portion 2a: Fine wire portion 2aa made of superconductor: Common portions 2b, 2c, 2d with fine wire portion 3a: Josephson junction 3: Qubit read portion 3a: Thin wire portion 3b made of superconductor : Josephson junction 3c, 3d: Current terminal 10: Insulating substrate 11, 13: Superconductor layer 12: Insulating film 15: Superconducting qubit device (second superconducting qubit device)
20: Integrated circuit using superconducting qubit device 22: Magnetic flux transfer device 22a: Magnetic flux transfer unit 22b: Superconducting quantum interference device unit 22c, 22d: Josephson junctions 23, 24, 25: Control line

Claims (9)

A superconducting qubit unit and a qubit readout unit connected to the superconducting qubit unit,
The superconducting qubit part is composed of a superconducting quantum interference device having three Josephson junctions,
The qubit readout unit is composed of a superconducting quantum interference device having two Josephson junctions,
A superconducting qubit device characterized in that one of the Josephson junctions of the qubit readout section is configured to be shared with one of the Josephson junctions of the superconducting qubit section.   The superconducting qubit part and the qubit reading part are formed of a loop-like thin line, and the thin line part in which the shared Josephson junction is formed among the thin lines is configured as a shared part. The superconducting qubit device according to claim 1.   The superconducting qubit device according to claim 1 or 2, wherein the magnetic flux in the loop of the qubit reading unit is controlled to a value other than a half integer or an integral multiple of the flux quanta at the time of reading. An integrated circuit using a plurality of superconducting qubit devices,
Each of the superconducting qubit devices comprises a superconducting qubit unit and a qubit reading unit connected to the superconducting qubit unit,
The superconducting qubit part is composed of a superconducting quantum interference device having three Josephson junctions,
The qubit readout unit is composed of a superconducting quantum interference device having two Josephson junctions,
An integrated circuit, wherein one of the Josephson junctions of the qubit readout unit is configured to be shared with one of the Josephson junctions of the superconducting qubit unit.   The superconducting qubit part and the qubit reading part are formed of a loop-like thin line, and the thin line part in which the shared Josephson junction is formed is configured as a shared part among the thin lines. The integrated circuit according to claim 4.   6. The integrated circuit according to claim 4, wherein the magnetic flux in the loop of the qubit reading unit is controlled to a value other than a half integer or an integral multiple of the magnetic flux quantum at the time of reading.   The integrated circuit according to claim 4, wherein a magnetic flux transfer device is disposed between the adjacent superconducting qubit devices.   The integrated circuit according to claim 4, wherein a control line is disposed adjacent to the superconducting qubit portion.   The integrated circuit according to claim 7, wherein a control line is disposed adjacent to the magnetic flux transfer device.

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