Quantum information processing device, quantum computer, and method for controlling quantum bit

Abstract

To reduce influence which a vibration magnetic field to be given for quantum bit control exerts on the calculation accuracy of quantum calculation.SOLUTION: A quantum information processing device has a quantum bit array for configuring quantum dots and potential barriers in an array shape, bit lines and word lines extending in mutually different directions for making current for controlling quantum bits held by the quantum dots and the potential barriers flow, and AC magnetic field application wiring for making an AC current for applying an AC magnetic field to the quantum bits flow. The device is configured such that an angle formed between extension directions of the bit lines and the word lines and an extension direction of the AC magnetic field application wiring is not an angle that is a multiple of 0 degree or 90 degrees.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a quantum information processing device that enables quantum computation, and more particularly to a quantum information processing semiconductor device in which a quantum bit array that enables quantum computation is fabricated using a semiconductor manufacturing method. [Background technology]

[0002] While existing computers handle the binary values ​​of 0 and 1, research and development is being actively conducted on quantum computers that can handle these superposition states as quantum bits (Qubits). Qubits can be realized using semiconductor elements. Each quantum bit has its own unique resonant frequency, and the state of the quantum bit can be changed when irradiated with microwaves having the same frequency as the resonant frequency.

[0003] Patent Document 1 proposes a technique for enabling quantum bits to be expanded two-dimensionally using current semiconductor manufacturing methods in a quantum information processing device.

[0004] Patent Document 2 discloses a quantum bit array comprising a semiconductor layer, an insulating layer disposed on the semiconductor layer, and a plurality of first gate electrodes disposed on the insulating layer and configured to trap electrons of a predetermined spin state in the semiconductor layer by application of a voltage, the quantum bit array being characterized in that, when changing the spin state of the electrons, the quantum bit array has a means for passing a current through at least one of the first gate electrodes in the extension direction of the first gate electrode for forming a magnetic field acting on the electrons. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-027142 [Patent Document 2] JP 2022-130893 A Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Documents 1 and 2 disclose techniques for implementing quantum bits using electron spin, and describe examples in which calculations in a quantum computer are implemented by controlling electron spin implemented in a semiconductor integrated circuit (LSI). The electron spin is controlled using the electron spin resonance phenomenon. In the electron spin resonance phenomenon, the electron spin is controlled using a static magnetic field and an oscillating magnetic field. The magnitude of the static magnetic field is related to the frequency of the oscillating magnetic field to which the electron spin reacts. The amplitude of the oscillating magnetic field is related to the speed at which the electron spin flips between the up and down states.

[0007] As described above, when controlling the electron spin, it is necessary to apply a signal of, for example, several tens of GHz to the electron spin to form an oscillating magnetic field (AC magnetic field). As disclosed in Patent Document 1, when making a quantum bit two-dimensionally expandable using a semiconductor manufacturing method, it is necessary to provide multiple conductor wirings that extend in different directions. At this time, an AC magnetic field is also applied to the polysilicon and conductor wirings in the LSI, generating an induced current, and a potential difference occurs between the wirings due to the current and the resistance of the wiring, generating an electric field. Note that it is also possible in principle to use the spin of holes instead of electrons.

[0008] The electric field induced around the electron spin by the magnetic field acts as a disturbance to the control of the electron spin. Specifically, it becomes a factor of variation in the control of the electron spin itself. Alternatively, it becomes a factor of variation in the control of the interaction between two electron spins. As a result, there is a risk that the calculation accuracy of quantum computing will deteriorate.

[0009] Therefore, an object of the present invention is to reduce the effect of an oscillating magnetic field applied for controlling quantum bits on the calculation accuracy of quantum computation. [Means for solving the problem]

[0010] A preferred aspect of the present invention is a quantum information processing device comprising: a quantum bit array in which quantum dots and potential barriers are arranged in an array; bit lines and word lines extending in different directions for carrying currents that control the quantum bits held in the quantum dots and the potential barriers; and AC magnetic field application wiring for carrying AC currents that apply an AC magnetic field to the quantum bits, wherein the angle between the extension direction of the bit lines and word lines and the extension direction of the AC magnetic field application wiring is not 0 degrees or a multiple of 90 degrees.

[0011] Another preferred aspect of the present invention is a quantum computer comprising a memory device, a general arithmetic unit, a control device, an input device, an output device, and a quantum arithmetic unit, wherein the quantum information processing device described above constitutes the quantum arithmetic unit, and the operation of the quantum arithmetic unit is controlled by the control device.

[0012] Another preferred aspect of the present invention is a method for controlling a quantum bit, comprising: a quantum information processing device including a quantum bit array in which quantum dots and potential barriers are arranged in an array; bit lines and word lines extending in different directions for passing a current that controls the quantum bits held in the quantum dots and the potential barriers; and AC magnetic field application wiring for passing an AC current that applies an AC magnetic field to the quantum bits; and, when controlling the state of the quantum bits, applying a static magnetic field to the quantum bits and passing an AC current from a first position to a second position of the AC magnetic field application wiring, so that a line connecting the first position and the second position does not intersect with the extension direction of the bit lines and word lines at an angle of 0 degrees or a multiple of 90 degrees. Effect of the Invention

[0013] The effect of the oscillating magnetic field applied for quantum bit control on the accuracy of quantum computing can be reduced. [Brief description of the drawings]

[0014] [Figure 1]FIG. 2 is a two-sided view of a quantum information processing device according to an embodiment. [Diagram 2] FIG. 1 is a perspective view showing an example of the configuration of a quantum dot array. [Diagram 3] FIG. 13 is a schematic diagram for explaining the effect of an RF signal wiring arrangement according to a comparative example. [Figure 4] FIG. 4 is a schematic diagram for explaining the effect of the RF signal wiring arrangement according to the embodiment. [Diagram 5] 1A to 1C are schematic diagrams illustrating examples of RF signal wiring arrangements according to a comparative example and an embodiment. [Figure 6] FIG. 11 is a schematic diagram for explaining an example of an RF signal wiring arrangement according to the second embodiment. [Figure 7] FIG. 13 is a schematic diagram for explaining an example of an RF signal wiring arrangement according to the fourth embodiment. [Figure 8] FIG. 23 is a schematic diagram for explaining an example of an RF signal wiring arrangement according to the sixth embodiment. [Figure 9A] FIG. 11 is a plan view of a quantum information processing device 1100 of a comparative example. [Figure 9B] FIG. 11 is a graph showing the electric field and magnetic field characteristics of the quantum information processing device 1100 of the comparative example. [Figure 10A] FIG. 12 is a plan view of a quantum information processing device 1200 according to an embodiment. [Figure 10B] FIG. 12 is a graph showing the electric field and magnetic field characteristics of the quantum information processing device 1200 of the embodiment. [Figure 11] FIG. 1 is a block diagram showing an example of a quantum computer configuration according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The embodiments will be described in detail with reference to the drawings. However, the present invention should not be interpreted as being limited to the description of the embodiments shown below. It will be easily understood by those skilled in the art that the specific configuration can be changed without departing from the concept or purpose of the present invention.

[0016] In the configurations of the embodiments described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and duplicated explanations may be omitted.

[0017] When there are multiple elements having the same or similar functions, they may be described by using the same reference numerals with different subscripts. However, when there is no need to distinguish between multiple elements, the subscripts may be omitted.

[0018] The designations "first," "second," "third," and the like in this specification are given to identify components, and do not necessarily limit the number, order, or content. Furthermore, numbers for identifying components are used in different contexts, and a number used in one context does not necessarily indicate the same configuration in another context. Furthermore, a component identified by a certain number does not prevent the component from also having the function of a component identified by another number.

[0019] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings, etc. may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings, etc.

[0020] All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety.

[0021] As used herein, elements referred to in the singular are intended to include the plural unless the context clearly indicates otherwise.

[0022] In one embodiment described in detail below, a semiconductor device having quantum dots performs spin control by applying a current to an RF signal wiring for applying an AC magnetic field and irradiating an AC magnetic field (oscillating magnetic field). The quantum dot to be controlled is selected by applying a voltage to the word line and the bit line. When an AC magnetic field is irradiated to the quantum dot, a voltage is generated in the quantum dot at the T-shaped portion of the bit line due to an induced electromotive force caused by the magnetic field in the word line and the bit line. The voltage generated in the quantum dot becomes a noise factor in spin control. In addition, the voltage generated in the potential barrier is a noise factor in interaction control, and it is desirable to reduce it. The angle between the word line, the bit line, and the RF signal wiring is preferably 45 degrees, thereby reducing the voltage that causes noise. EXAMPLES

[0023] 1 is a two-sided view showing a part of a quantum information processing device of an embodiment. A top view, an AA′ cross-sectional view, and a BB′ cross-sectional view are shown. The x-axis and y-axis directions for the top view, and the x-axis and z-axis directions for the cross-sectional view are shown in the figures.

[0024] The cross-sectional structure of the quantum information processing device 100 is, for example, a laminated structure of a semiconductor substrate 2 such as silicon, a first gate insulating layer 3, a first gate electrode layer 4, a second gate insulating layer 5, a second gate electrode layer 6, an upper insulating layer 7, and a metal electrode layer 8. The first gate insulating layer 3, the second gate insulating layer 5, and the upper insulating layer 7 are, for example, silicon oxide films. The first gate electrode layer 4 and the second gate electrode layer 6 are, for example, metal gate wiring layers made of polysilicon, Ta, Nb, or the like. The metal electrode layer 8 is, for example, copper or aluminum. Although a description of known techniques will be omitted, the quantum information processing device 100 generally operates at an extremely low temperature near absolute zero by a dilution refrigerator or the like.

[0025] A quantum bit array 1 that holds quantum bits is formed on a semiconductor substrate 2. A quantum bit carries quantum information, and a quantum dot can be likened to a container that holds the quantum bit. In this specification, a structure that can hold quantum bits in a two-dimensional array is called a quantum bit array.

[0026] 1 shows the configuration of one quantum bit array 1 and its surroundings (for example, a 20 μm square area) in one quantum information processing device. The quantum information processing device may be equipped with one or more quantum bit arrays.

[0027] A GND wiring 9 and an RF signal wiring 10 are formed on the metal electrode layer 8. The GND wiring 9 and the RF signal wiring 10 form a coplanar waveguide.

[0028] As will be described later, quantum dots and potential barriers are formed by semiconductor transistors in the quantum bit array 1. The quantum dot transistors and potential barrier transistors are arranged alternately in the bit line direction (x-axis direction) and the word line direction (y-axis direction).

[0029] Word lines for applying voltages to the gates of the quantum dot transistor and the potential barrier transistor are arranged, for example, to extend in the y-axis direction on the first gate electrode layer 4. Bit lines for applying voltages to the gates of the quantum dot transistor and the potential barrier transistor are arranged, for example, to extend in the x-axis direction on the second gate electrode layer 6.

[0030] In this embodiment, the RF signal wiring 10, which applies an AC current of tens to several tens of GHz to generate an oscillating magnetic field (AC magnetic field), extends at an angle of 45 degrees with respect to the x-axis and y-axis directions. As a result of this configuration, the AC current flows at an angle of 45 degrees with respect to the word lines and bit lines.

[0031] The quantum information processing device 100 shown in FIG. 1 has a square area with sides of 20 μm, for example, and the quantum bit array 1 disposed approximately in the center has a square area with sides of 2 μm, for example. In reality, wiring for inputting and outputting signals to and from the quantum bit array 1 is formed in the first gate electrode layer 4, the second gate electrode layer 6, or other wiring layers. However, these wirings are not shown in the top view of FIG. 1 to avoid complexity. The metal electrode layer 8 has a thickness of, for example, 5 μm. In this example, the width of the RF signal wiring 10 is 5 μm, and is configured to cover the entire quantum bit array 1. The configuration of FIG. 1 is an example, and other wiring layers and insulating layers may be further provided.

[0032] Although not shown in FIG. 1, the quantum information processing device 100 may be configured to constantly apply a static magnetic field of, for example, 0.7 T to the entire device, if necessary.

[0033] 2 is a perspective view showing a configuration example of a portion of the quantum bit array 1. A silicon channel C is formed in a semiconductor substrate 2 so as to extend in the x-axis direction and the y-axis direction. Quantum dot transistors for forming quantum dots and potential barrier transistors for forming potential barriers are alternately arranged in the bit line direction (x-axis direction) and the word line direction (y-axis direction).

[0034] 2, a first potential barrier gate line 2021 (sometimes abbreviated as PG1) and a first quantum dot gate line 2022 (sometimes abbreviated as DG1) are formed in the first gate electrode layer 4. A second potential barrier gate line 2031 (sometimes abbreviated as PG2) and a second quantum dot gate line 2032 (sometimes abbreviated as DG2) are formed in the second gate electrode layer 6. Hereinafter, the first potential barrier gate line 2021 and the first quantum dot gate line 2022 may be referred to as a word line W, and the second potential barrier gate line 2031 and the second quantum dot gate line 2032 may be referred to as a bit line B.

[0035] The first gate electrode layer 4 and the second gate electrode layer 6 apply voltage to the gates of the quantum dot transistor and the potential barrier transistor via the first gate insulating layer 3, which is made of, for example, 5 nm thick SOI (Silicon On Insulator). In Fig. 2, the first gate insulating layer 3 is left as a gap so that the arrangement of the quantum dots and potential barrier can be seen. In the quantum dots, for example, electron spins are arranged as quantum bits. The potential barrier controls the coupling between quantum bits and the movement of the quantum bits.

[0036] The second potential barrier gate line 2031 and the second quantum dot gate line 2032 are extended in the z direction toward the silicon channel C at the T-shaped portion 2000, and a voltage can be applied via the first gate insulating layer 3.

[0037] When actually constructing a quantum bit array, the array structure shown in Fig. 2 is expanded two-dimensionally to increase capacity. Examples of quantum bit operations in a two-dimensional array structure are also described in Patent Document 1 and Patent Document 2, so details are omitted here and an example of the operating principle is described below.

[0038] Basically, when an AC current is passed through the RF signal wiring 10 and an AC magnetic field is applied to the quantum bit, electron spin rotation occurs when the energy difference between the quantum states |0> and |1> of the quantum bit matches the energy difference hν (h is Planck's constant) corresponding to the frequency ν of the RF pulse. This method allows for rotation gate operation. By controlling the magnitude and time width of the RF pulse, rotation gate operation of any magnitude can be performed. For example, applying an RF pulse equivalent to a phase π results in a NOT gate operation. To selectively operate quantum bits, a static magnetic field is applied to any quantum bit and the energy difference between |0> and |1> is set by Zeeman splitting.

[0039] For example, when manipulating a quantum bit immediately below the T-shaped portion 2000 constituted by the second quantum dot gate line 2032, an AC magnetic field is applied by passing an AC current through the RF signal wiring 10, currents in opposite directions are passed through the two first potential barrier gate lines 2021 sandwiching the T-shaped portion 2000, and currents in opposite directions are passed through the two second potential barrier gate lines 2031 sandwiching the second quantum dot gate line 2032, the generated static magnetic field is concentrated on the quantum bit surrounded by the wiring, and the quantum bit is manipulated by controlling the energy difference of the quantum bit by the Zeeman effect. Alternatively, there is also a method of manipulating the quantum bit by passing a current through the second quantum dot gate line 2032 to change the energy difference of the quantum bit by the Stark effect.

[0040] In addition, the voltage of the first potential barrier gate line 2021 and the second potential barrier gate line 2031 controls the potential barrier directly below the T-shaped portion 2000 formed by the second potential barrier gate line 2031, causing quantum entanglement and interaction between adjacent quantum bits on the silicon channel C in the y direction.

[0041] In the silicon channel C in the x direction, interaction between two quantum bits is not possible in the portion other than the T-shaped portion 2000, but movement of quantum bits and single quantum bit operation are possible. Single quantum bit operation is also basically realized by the above-mentioned Zeeman effect and Stark effect.

[0042] As described above, the quantum information processing device 100 having quantum dots performs spin control by applying a current to the RF signal wiring 10 for applying an AC magnetic field and irradiating an AC magnetic field. The quantum dot to be controlled is selected by applying a voltage to the word line W and the bit line B. When an AC magnetic field is irradiated, a potential difference occurs between the adjacent word line W and bit line B due to an induced electromotive force caused by the AC magnetic field.

[0043] In particular, around the T-shaped portion 2000, among the bit lines and word lines, the wiring formed in the second gate electrode layer 6 protrudes toward the first gate electrode layer 4 and is close to the silicon channel C, and the word lines W and bit lines B cross in a complex manner. Therefore, the generated electric field is complex and has a large effect on quantum calculation. If the electric field affects the quantum dots immediately below the T-shaped portion 2000 of the second quantum dot gate line 2032, it becomes a noise factor in spin control. In addition, the electric field that affects the potential barrier immediately below the T-shaped portion 2000 of the second potential barrier gate line 2031 is a noise factor in interaction control, and it is desirable to reduce it.

[0044] In this embodiment, the voltage that causes noise is reduced by making the angle between the word line W, the bit line B, and the RF signal wiring 10 other than 90 degrees. In a preferred example, the angle between the word line W, the bit line B, and the RF signal wiring 10 is set to 45 degrees.

[0045] FIG. 3 is a schematic diagram for explaining the problem that the embodiment focuses on. The upper part is a schematic diagram of the quantum information processing device 100 as viewed from the semiconductor substrate 2 side, and the lower part is a cross-sectional view thereof. When the word line W and the RF signal wiring 10 are arranged in parallel, an AC magnetic field H is generated by the AC current I flowing through the RF signal wiring 10, and a current indicated by an arrow is induced in the word line W. On the other hand, a smaller current (almost zero) is induced in the bit line B arranged perpendicular to the RF signal wiring 10. In this way, different magnetic field induced currents are generated in the word line W and the bit line B, and a potential difference is generated between the word line W and the bit line B due to the resistance of each wiring. As a result, a voltage is generated in the area where the word line W and the bit line B are close to each other.

[0046] Fig. 4 is a schematic diagram showing the operation of the embodiment. If the angle between the RF signal wiring 10 and the word line W and bit line B is 45 degrees, and if the wiring resistance of the word line W and the wiring resistance of the bit line are equal, the magnitude of the induced current in the word line W and the induced current in the bit line B will be equal, and the potential difference between the word line W and the bit line B will theoretically be zero. For example, if the word line W and the bit line B are made of the same material and have the same cross-sectional area, the potential difference between the lines will be smaller than in the example of Fig. 3. Therefore, the effect of the oscillating magnetic field applied for quantum bit control on the calculation accuracy of quantum computing can be reduced.

[0047] 5 is an explanatory diagram showing a state in which the arrangement of the GND wiring 9 and the RF signal wiring 10 is changed from that of the comparative example (left side) to that of the embodiment (right side). The quantum information processing device 100 corresponds to a region including one quantum bit array 1 shown in FIG. 1. An example of the wiring dimensions is shown in the figure. EXAMPLES

[0048] 6 shows a case where a plurality (three) of quantum information processing devices 100, each including one quantum bit array 1, are integrated and mounted on the same substrate. The RF signal wiring 10, of which only the center line is shown, intersects with the word line W and bit line B at 45 degrees. When multiple quantum information processing devices 100 are provided, the RF signal wiring 10 may be arranged in a serpentine manner as shown in FIG. EXAMPLES

[0049] In this embodiment, a design method is described in which the induced current in the word line W and the induced current in the bit line B due to the oscillating magnetic field from the RF signal wiring 10 are balanced to suppress the generation of unnecessary electric fields. In the quantum bit array of this embodiment, in a quantum semiconductor device in which quantum dots are formed, an arbitrary quantum dot is selected by controlling the wiring layers of the bit line and the word line, and an AC magnetic field is applied to the selected quantum dot to control the spin. At this time, in order to provide a quantum computer that can measure the spin of the quantum dot with high accuracy by reducing the spin control error and the interaction control error caused by the potential difference generated between the bit line and the word line, the following features are provided.

[0050] First, when there is a bit line B and a word line W that is perpendicular to the bit line B, it is necessary to avoid the angle between the bit line B and the word line W and the RF signal wiring 10 being 0 degrees or a multiple of 90 degrees. In other words, when the angle between the bit line B and the word line W and the RF signal wiring 10 is 0 degrees or a multiple of 90 degrees, an unwanted electric field is most likely to be generated.

[0051] Additionally, the wiring lengths of the bit line B and the word line W are made as equal as possible in the region directly below the RF signal wiring 10. This is to make the currents induced in the bit line B and the word line W as equal as possible. At this time, the electrical resistance per length of the bit line B and the word line W is also made as equal as possible. EXAMPLES

[0052] In this embodiment, when the distance between the RF signal wiring 10 and the bit line B is GB and the distance between the RF signal wiring 10 and the word line W is GW, the ratio of the square of GB to the square of GW in the region directly below the RF signal wiring 10 is configured to be as equal as possible to the ratio of the wiring length LB of the bit line B to the wiring length LW of the word line W.

[0053] The reason for adopting the above method will be explained below. The current induced by the magnetic field can be explained as follows. Magnetic field induced current ∝ magnetic field ÷ (distance between wires) 2 ×Wiring length…(Formula 1) 7 is a schematic diagram showing the positional relationship between the bit line B and the word line W and the RF signal wiring 10. At this time, the current IB induced in the bit line B and the current IW induced in the word line W are as follows. IB=1 / (GB) 2 ×LB…(Formula 2) IW=1 / (GW) 2 ×LW …(Formula 3) In this case, if IB and IW are made equal, they will be balanced. That is, 1 / (GB) 2 ×LB=1 / (GW) 2 ×LW…(Formula 4) The condition for making the ratio of the square of GB to the square of GW equal to the ratio of the wiring length LB of the bit line B to the wiring length LW of the word line W can be derived. EXAMPLES

[0054] Since the induced current has a particularly large effect on quantum bit arrays, it is desirable to avoid the angle between the bit line B and word line W and the RF signal wiring 10 being 0 degrees or a multiple of 90 degrees in the region where quantum bits exist. Also, in the region where quantum bits do not exist, the angle between the extension direction of the bit line B and word line W and the RF signal wiring 10 may be 0 degrees or 90 degrees. EXAMPLES

[0055] As shown in FIG. 6 above, multiple quantum bit arrays can be formed on one plane. Furthermore, multiple quantum bit arrays can be stacked in the thickness direction (perpendicular to the plane). That is, the configuration shown in FIG. 1 can be stacked in the z direction to improve integration. In this case, for example, the quantum dots and the RF signal wiring are manufactured separately and positioned by bonding them together. At this time, the stacking is staggered. It is desirable to stack them while changing the direction of the RF signal wiring 10, for example, by shifting them horizontally or stacking them rotated by 90 degrees.

[0056] Fig. 8 is a schematic diagram showing the pattern of RF signal wiring 10 when the configuration of Fig. 6 is stacked. By alternately stacking patterns A and B, which are mirror images, the RF signal wiring 10 crosses at 90 degrees between quantum bit arrays adjacent in the stacking direction. This configuration prevents biased effects of AC magnetic fields. EXAMPLES

[0057] The shape of the coplanar waveguide is not limited to that shown in Fig. 1. The GND wiring 9 and the RF signal wiring 10 may be tapered or have a gently curved shape. Also, the thickness may vary depending on the location. EXAMPLES

[0058] In order to equalize the electromotive forces caused by the currents flowing through the word lines W and bit lines B, the electromotive forces can be cancelled out by, for example, meandering or reciprocating the wiring connected to the word lines W and bit lines B. For example, in this case, the electromotive force can be adjusted by forming the wiring connected to at least one of the word lines W and bit lines B in a meandering wiring pattern in the area outside the quantum bit array 1 and covered by the RF signal wiring 10. EXAMPLES

[0059] The following describes the operations of the quantum information processing device 1100 of the comparative example and the quantum information processing device 1200 of the embodiment.

[0060] 9A is a plan view of a quantum information processing device 1100 of a comparative example. The quantum information processing device 1100 has a side length of about 40 μm, and a quantum bit array 1 having a side length of about 2 μm is disposed in the center. The basic structure of the quantum bit array 1 is as shown in FIG.

[0061] Wiring is provided from the quantum bit array 1 to the input / output terminals around the elements. The distance between the GND wiring 9 and the RF signal wiring 10 is 5 μm. The RF signal wiring 10 has a width of 5 μm and covers the entire quantum bit array 1. It is parallel to the word lines W and perpendicular to the bit lines B.

[0062] 9B is a graph showing the electric field distribution and the magnetic field distribution on the silicon channel C in the X-axis and Y-axis directions of FIG. 9A. Measurements were taken over a range of about 6 μm, with the central range of about 2 μm corresponding to the quantum bit array 1.

[0063] The electric field in the X-axis direction is 0 to 2×10 6 The electric field varies widely in the range of V / m. In the quantum bit array 1, the valley of the electric field corresponds to the T-shaped portion 2000. The electric field in the Y-axis direction is 2.5×10 5 ~5×10 5The electric field varies in the range of V / m. Eight peaks of the electric field are observed in the quantum bit array 1. In the quantum bit array 1 of the embodiment, there are eight pairs of the second potential barrier gate line 2031 (PG2) and the second quantum dot gate line 2032 (DG2), and the peaks correspond to these pairs.

[0064] The magnetic field along the X axis varies widely from 20 to 200 B. The magnetic field along the Y axis varies from 40 to 120 B. 10A is a plan view of a quantum information processing device 1200 of the embodiment. The quantum information processing device 1200 has a side length of approximately 40 μm, and one quantum bit array 1 having a side length of approximately 2 μm is disposed in the center. Wiring is provided from the quantum bit array 1 to input / output terminals around the quantum information processing device 1200. The spacing between the GND wiring 9 is a maximum of 35 μm. The RF signal wiring 10 is 5 μm wide and covers the entire quantum bit array 1. At the sides of the quantum information processing device 1200, the spacing between the RF signal wiring 10 and the GND wiring 9 is 5 μm.

[0065] The RF signal wiring 10 basically extends in the Y-axis direction, but is bent at 45° at a location where it does not overlap with the quantum bit array 1, and is arranged so that it is at 45° with the word line W and 45° with the bit line B. Since electrical signals may be disturbed at the location where the RF signal wiring 10 is bent, it is considered that the state of the electric field and magnetic field changes depending on the bending position. The effect of bending on the quantum bit array 1 is smaller if the wiring is bent at a position away from the quantum bit array 1, but there is a disadvantage that the integration degree is reduced. In this embodiment, the wiring is bent at a location at least the width (2 μm) of the quantum bit array 1 away from the end of the quantum bit array 1.

[0066] The angle can be determined based on the center line if the RF signal wiring 10 has a line-symmetric shape (same width). Alternatively, the contour line of the RF signal wiring 10 can be used as the reference. Generally, the width of the wiring is uniform and the contour is straight, so there is no significant difference between the two. In the embodiment, the wiring is arranged to be at 45° to the word line W and at 45° to the bit line B, but there is a certain effect if the angle between the RF signal wiring 10 and the word line W direction or the bit line B direction is not 0 degrees or a multiple of 90 degrees.

[0067] FIG. 10B is a graph showing the electric field distribution and the magnetic field distribution on the silicon channel C in the X-axis and Y-axis directions of FIG. 10A. The measurement was performed over a range of about 6 μm, and the central range of about 2 μm corresponds to the quantum bit array 1. The electric field in the X-axis direction is 0 to 7.5×10 5 The electric field fluctuates in the range of 0 to 2×10 V / m, but in the quantum bit array 1 part, the electric field variation is reduced by 62% compared to the comparative example. 5 Although the electric field fluctuations are in the range of V / m, in the quantum bit array 1 part, the electric field fluctuations are reduced by 75% compared to the comparative example. Since the quantum bits exist in the quantum bit array 1 part, it is important to suppress the electric field fluctuations in the quantum bit array 1 part.

[0068] The magnetic field in the X-axis direction fluctuates in the range of 70 to 100 B, but in the quantum bit array 1 part, the magnetic field variation is reduced by 80% compared to the comparative example. The magnetic field in the Y-axis direction fluctuates in the range of 70 to 110 B, but in the quantum bit array 1 part, the magnetic field variation is reduced by 80% compared to the comparative example.

[0069] As described above, according to the configuration of the embodiment, when an AC magnetic field is irradiated by a signal of several tens of GHz to control the spin of a quantum bit and control the interaction between quantum bits, the angle between the word line, the bit line, and the RF signal wiring for applying an AC magnetic field is arranged at 45°. With this configuration, the induced electromotive force generated in each wiring is approximately equal, the potential difference between the wirings is small, and the electric field between each wiring can be reduced. Therefore, the electric field induced in the quantum dot electrode can be reduced, the noise of the spin control voltage and the interaction voltage of the quantum bit array is reduced, and the accuracy of the electron spin control and the potential barrier control is improved. Therefore, the calculation error rate of the quantum computer can be reduced.

[0070] In order to achieve high two-dimensional integration of quantum bit arrays, it is important to have a configuration in which RF signal wiring is shared by multiple quantum bits, and this is an effective means of reducing the overall noise of each quantum bit's spin and interaction voltage. EXAMPLES

[0071] An example of the quantum computer configuration of this embodiment is shown in Fig. 11. Fig. 11 is similar to the configuration of a normal computer, but is characterized by including a quantum information processing device 100. The quantum information processing device 100 is a part that exclusively performs the quantum mechanical operations described in the first to ninth embodiments. Other general operations are performed by a general processing device 2002.

[0072] The above configuration may be configured as an integrated computer, or any of the parts such as the main memory device 2001, general arithmetic unit 2002, control device 2003, auxiliary memory device 2004, input device 2005, and output device 2006 may be configured as other computers connected via a network.

[0073] General calculations are performed in the same manner as in a normal computer. Data is exchanged between the main memory device 2001, which is the storage unit, and the general calculation unit 2002, which is the calculation unit, and calculations are carried out by repeating this process. At this time, the control unit 2003 directs the entire system. Programs executed by the general calculation unit 2002 are stored in the main memory device 2001, which is the storage unit. If the storage capacity of the main memory device 2001 is insufficient, the auxiliary memory device 2004, which is also a storage unit, is used. An input device 2005 is used to input data, programs, etc., and an output device 2006 is used to output the results. The input device 2005 includes a manual input device such as a keyboard, as well as an interface for network connection. This interface also serves as an output device.

[0074] Quantum operations are also performed in a similar manner. Data is exchanged between the main memory device 2001, which is the storage unit, and the quantum information processing device 100, which is the operation unit, and the operation is carried out by repeating this process. The control device 2003 controls the whole process. The program executed by the quantum information processing device 100 is stored in the main memory device 2001, which is the storage unit.

[0075] The program is converted into a code used by the quantum information processing device 100 using the general arithmetic unit 2002, and stored in the main memory device 2001. If there is insufficient storage capacity, the auxiliary memory device 2004, which is also a storage unit, is used. This encoded program is sent from the main memory device 2001 to the quantum information processing device 100, and the control device 2003 sends a control signal to the quantum information processing device 100 in accordance with the encoded program to execute the calculation. The execution results of the quantum information processing device 100 are sent to the main memory device 2001, and are post-processed by the general arithmetic unit 2002 as necessary.

[0076] As described above, in this embodiment, it is possible to suppress disturbances in the electric and magnetic fields caused by the AC current in the RF signal wiring 10 in the quantum information processing device 100. Therefore, it is possible to reduce the influence of the oscillating magnetic field applied for quantum bit control on the calculation accuracy of quantum computation.

[0077] According to the above embodiment, the calculation accuracy of quantum computing can be improved, which can be used for various optimization simulations, resulting in less energy consumption, reduced carbon emissions, prevention of global warming, and contribution to the realization of a sustainable society. [Explanation of symbols]

[0078] Quantum bit array 1, semiconductor substrate 2, first gate insulating layer 3, first gate electrode layer 4, second gate insulating layer 5, second gate electrode layer 6, upper insulating layer 7, metal electrode layer 8, GND wiring 9, RF signal wiring 10, quantum information processing device 100, T-shaped portion 2000, first potential barrier gate line (PG1) 2021, first quantum dot gate line (DG1) 2022, second potential barrier gate line (PG2) 2031, second quantum dot gate line (DG2) 2032

Claims

1. a quantum bit array in which quantum dots and potential barriers are arranged in an array; a bit line and a word line extending in different directions for passing a current for controlling the quantum bit held in the quantum dot and the potential barrier; and an AC magnetic field application wiring for passing an AC current that applies an AC magnetic field to the quantum bit; the angle between the extending direction of the bit line and the word line and the extending direction of the AC magnetic field application wiring is not 0 degrees or a multiple of 90 degrees; Quantum information processing device.

2. the angle between the extending direction of the bit line and the word line and the extending direction of the AC magnetic field application wiring is 45 degrees; The quantum information processing device according to claim 1.

3. The bit lines and the word lines are formed in different wiring layers, and their extension directions intersect at 90 degrees with each other. The quantum information processing device according to claim 1.

4. a first wiring layer and a second wiring layer located farther from the quantum dots than the first wiring layer; Among the bit lines and the word lines, the wiring formed in the second wiring layer has a T-shaped portion protruding toward the first wiring layer and adjacent to the quantum dot. The quantum information processing device according to claim 1.

5. The AC magnetic field application wiring is configured to cover the entire quantum bit array. The quantum information processing device according to claim 1.

6. The wiring lengths of the bit line and the word line are equal in a region directly below the AC magnetic field application wiring. The quantum information processing device according to claim 1.

7. When the shortest distance between the AC magnetic field application wiring and the bit line is DB and the shortest distance between the AC magnetic field application wiring and the word line is DW, In a region immediately below the AC magnetic field application wiring, a ratio of the square of DB to DW is equal to a ratio of the wiring lengths of the bit line and the word line. The quantum information processing device according to claim 1.

8. an angle between an extension direction of the bit lines and the word lines and an extension direction of the AC magnetic field application wiring is 0 degrees or 90 degrees in at least a part outside the region where the quantum bit array is present; In a region where the quantum bit array is present, an angle between an extension direction of the bit line and the word line and an extension direction of the AC magnetic field application wiring is not 0 degrees or a multiple of 90 degrees. The quantum information processing device according to claim 1.

9. The extension direction of the AC magnetic field application wiring is bent outside the region where the quantum bit array is present, In a region where the quantum bit array is present, an angle between an extension direction of the bit line and the word line and an extension direction of the AC magnetic field application wiring is not 0 degrees or a multiple of 90 degrees. The quantum information processing device according to claim 8.

10. By providing a plurality of the quantum bit arrays and meandering the AC magnetic field application wiring, In a region where the quantum bit array is present, an angle between an extension direction of the bit line and the word line and an extension direction of the AC magnetic field application wiring is not 0 degrees or a multiple of 90 degrees. The quantum information processing device according to claim 9.

11. a unit structure including at least a first layer in which the quantum bit array is formed, a second layer in which the bit lines and word lines are formed, and a third layer in which the AC magnetic field application wiring is formed, The unit structure is configured by laminating a plurality of the unit structures. The quantum information processing device according to claim 1.

12. In the unit structures adjacent to each other in the stacking direction, at least a part of the projection of the AC magnetic field application wiring is configured to intersect. The quantum information processing device according to claim 11.

13. In the adjacent unit structures, at least a part of the projection of the AC magnetic field application wiring is configured to intersect at 90 degrees. The quantum information processing device according to claim 12.

14. The present invention includes a storage device, a general arithmetic device, a control device, an input device, an output device, and a quantum arithmetic device, 13. A quantum computer, comprising: a quantum information processing device according to claim 1 constituting said quantum operation device, the operation of which is controlled by said control device.

15. As a quantum information processing device, a quantum bit array in which quantum dots and potential barriers are arranged in an array; a bit line and a word line extending in different directions for passing a current for controlling the quantum bit held in the quantum dot and the potential barrier; preparing an AC magnetic field application wiring for passing an AC current to apply an AC magnetic field to the quantum bit; When controlling the state of the quantum bit, a static magnetic field is applied to the quantum bit, and an AC current is caused to flow from a first position to a second position of the AC magnetic field application wiring, so that a line connecting the first position and the second position does not intersect with an extension direction of the bit line and the word line at an angle of 0 degrees or a multiple of 90 degrees. How quantum bits are controlled.

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