Electronic component, optical directional coupler, and method for controlling optical directional coupler

Abstract

The present invention provides: an electronic component which enables highly accurate move of a movable waveguide; an optical directional coupler; and a method for controlling an optical directional coupler.　An electronic component according to the present invention comprises: a first insulating part; a second insulating part which faces the first insulating part, while being relatively movable with respect to the first insulating part so that the distance between itself and the first insulating part changes; a first capacitor which comprises a first electrode that is provided on the first insulating part and a second electrode that is provided on the second insulating part; a second capacitor which comprises a third electrode that is provided on the first insulating part and a fourth electrode that is provided on the second insulating part; and an inductor which is connected to the second capacitor so as to constitute a resonance circuit.

Description

[Technical Field]

[0001] The present disclosure relates to an electronic component, an optical directional coupler, and a method for controlling an optical directional coupler. [Background technology]

[0002] Conventionally, there has been an optomechanical device (optical directional coupler) based on mode coupling, in which two intersecting waveguides (a horizontal input waveguide and a vertical output waveguide) and a movable coupler are arranged to intersect. The coupler is a curved movable waveguide that can be switched between a connected state connecting the two waveguides and a non-connected state. An electrostatic actuator is used to move the movable waveguide (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2003 / 0108274 Summary of the Invention [Problem to be solved by the invention]

[0004] In an optical directional coupler, extremely high positional accuracy is required when moving a movable waveguide relative to two waveguides to switch between a connected state and a disconnected state. However, conventional optical directional couplers do not incorporate any special ingenuity, making it difficult to move the movable waveguide with high accuracy.

[0005] Therefore, an object of the present invention is to provide an electronic component, an optical directional coupler, and a method for controlling an optical directional coupler, which are capable of moving a movable waveguide with high precision. [Means for solving the problem]

[0006] An electronic component according to an embodiment of the present disclosure includes a first insulating portion, a second insulating portion facing the first insulating portion and movable relative to the first insulating portion so that the distance between the first insulating portion and the second insulating portion changes, a first capacitor having a first electrode provided on the first insulating portion and a second electrode provided on the second insulating portion, a second capacitor having a third electrode provided on the first insulating portion and a fourth electrode provided on the second insulating portion, and an inductor connected to the second capacitor to form a resonant circuit. [Effects of the Invention]

[0007] It is possible to provide an electronic component, an optical directional coupler, and a method for controlling an optical directional coupler that can move a movable waveguide with high precision. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of a planar configuration of a quantum computer 1 according to an embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a beam splitter 30. [Figure 3] FIG. 2 is a diagram illustrating an example of the operation of the quantum computer 1. [Figure 4] 1 is a plan view showing an example of the configuration of an optical directional coupler 100. FIG. [Figure 5] 1 is a diagram showing an example of the configuration of a first insulating section 110, a second insulating section 120, a spring 130, and a movable waveguide 150 of an optical directional coupler 100. FIG. [Figure 6] 5A and 5B are diagrams showing an example of the configuration of a cross section taken along an arrow AA and a cross section taken along an arrow BB in FIG. 4. [Figure 7] FIG. 10 is a diagram illustrating dimensions related to a third electrode 115B and a fourth electrode 125B. [Figure 8] FIG. 1 is a diagram showing the optical directional coupler 100 in an ON state. [Figure 9] FIG. 10 is a diagram showing the optical directional coupler 100 in an off state. [Figure 10] FIG. 2 is a diagram showing an example of an equivalent circuit 160 of the optical directional coupler 100. [Figure 11]FIG. 2 is a diagram illustrating an example of a drive control unit 180. [Figure 12] FIG. 10 is a plan view showing an example of the configuration of an optical directional coupler 100M1 of a first modified example of the embodiment. [Figure 13] FIG. 10 is a plan view showing an example of the configuration of an optical directional coupler 100M2 of a second modified example of the embodiment. [Figure 14] FIG. 10 is a plan view showing an example of the configuration of an optical directional coupler 100M2 of a second modified example of the embodiment. [Figure 15] FIG. 10 is a plan view showing an example of the configuration of an optical directional coupler 100M3 according to a third modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments to which the electronic component, optical directional coupler, and optical directional coupler control method of the present disclosure are applied will be described.

[0010] <Embodiment> FIG. 1 is a diagram showing an example of the planar configuration of a quantum computer 1 according to an embodiment. In the following description, an XYZ coordinate system is defined. The direction parallel to the X axis (X direction), the direction parallel to the Y axis (Y direction), and the direction parallel to the Z axis (Z direction) are perpendicular to each other. Furthermore, a planar view refers to an XY plane view. In the following description, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand.

[0011] The quantum computer 1 includes waveguides 10 (10X, 10Y, 10S), movable waveguides 150 (150A, 150B), quantum bit elements 20, a beam splitter 30, a coupler 40, and a photodetector 50. Of these, the waveguides 10 (10X, 10Y, 10S) are fabricated by, for example, microfabrication of a silicon substrate or the like. The movable waveguides 150 (150A, 150B) are realized by MEMS (Micro Electro Mechanical Systems), as will be described in detail later. The quantum bit elements 20 are realized by diamond qubits using diamond color centers. The quantum computer 1 is a diamond qubit quantum computer.

[0012] The waveguide 10 has waveguides 10X, 10Y, and 10S. The waveguides 10X, 10Y, and 10S are waveguides through which light can propagate. The waveguides 10X extend in the X direction and are provided in plurality. The waveguides 10Y extend in the Y direction and are provided in plurality. The waveguides 10X and 10Y intersect. Note that the distance G1 between the waveguide 10X located at the end on the -X direction side and the waveguide 10S is, for example, approximately 500 μm, and the distance between adjacent waveguides 10X and the distance between adjacent waveguides 10Y are also the same.

[0013] The waveguide 10S is provided in a substantially rectangular ring shape so as to surround the peripheries of the waveguides 10X and 10Y. The four corners of the waveguide 10S are curved in a plan view to allow light to propagate inside. Both ends of the waveguides 10X and 10Y are not directly connected to the waveguide 10S, and an optical path through which light can propagate is formed by the movable waveguide 150. When the waveguides 10X, 10Y, and 10S are not to be particularly distinguished from one another, they will be simply referred to as waveguides 10.

[0014] Movable waveguide 150A is provided between waveguides 10X and 10Y and quantum bit device 20. Movable waveguide 150A is moved in an optical directional coupler, which will be described later, to switch between a connected state in which the end of waveguide 10X or 10Y is connected to waveguide 10S, and a disconnected state in which the end of waveguide 10X or 10Y is not connected to waveguide 10S. Hereinafter, the ability to switch between the connected state and the disconnected state will be referred to as being connectable / disconnectable.

[0015] Movable waveguide 150B is provided between both ends of waveguides 10X and 10Y and waveguide 10S. Movable waveguide 150B is moved in an optical directional coupler, which will be described later, to switch between a connected state in which waveguides 10X and 10Y are connected to quantum bit device 20 and a disconnected state in which waveguides 10X and 10Y are not connected to quantum bit device 20.

[0016] The movable waveguides 150A and 150B have the same configuration. Hereinafter, when there is no need to distinguish between the movable waveguides 150A and 150B, they will be simply referred to as the movable waveguide 150. Details of the movable waveguide 150 will be described later using FIG. 4 etc.

[0017] The quantum bit element 20 is provided along the waveguides 10X and 10Y. The quantum bit element 20 is realized by a diamond qubit using a diamond color center, and holds quantum bits. The quantum bits are electron spin, nuclear spin, and photon, or electron spin and photon.

[0018] The beam splitter 30 is connected to the periphery of the waveguide 10S. The beam splitter 30 will be described with reference to FIG. 2 in addition to FIG. 1. FIG. 2 is a diagram showing an example of the configuration of the beam splitter 30. The beam splitter 30 has two waveguides 31 and 32 arranged in an X-shape in a plan view, and one end of each of the waveguides 31 and 32 is connected to a coupler 40. A movable waveguide 150 is provided at the other end of each of the waveguides 31 and 32 so as to be movable toward and away from the waveguide 10S. When either of the two movable waveguides 150 is in a connected state, the beam splitter 30 is connected to the waveguide 10S. The width W1 of the beam splitter 30 is approximately 50 μm.

[0019] The coupler 40 is an optical coupler that couples the beam splitter 30 and the photodetector 50. The photodetector 50 detects the light input via the coupler 40. The photodetector 50 may be, for example, an avalanche photodiode (APD) or a superconducting nanowire photon detector (SNSPD). Note that the coupler 40 may be omitted if photons are detected directly from the waveguide 10S.

[0020] <Operation of Quantum Computer 1> 3 is a diagram illustrating an example of the operation of the quantum computer 1. Here, entanglement is explained. Entanglement is a state in which quantum bits cannot recognize each other when performing a quantum operation.

[0021] Two quantum bit elements 20 (two quantum bit elements 20 indicated by arrows A and B) corresponding to the two quantum bits to be entangled are selected, and one beam splitter 30 (beam splitter 30 indicated by arrow C) for entangling the two quantum bits is selected. The path from the quantum bit element 20 indicated by arrow A to the beam splitter 30 indicated by arrow C is indicated by the path indicated by the dashed line. The path from the quantum bit element 20 indicated by arrow B to the beam splitter 30 indicated by arrow C is indicated by the path indicated by the dashed line. By connecting the movable waveguide 150 (movable waveguide 150 indicated by arrows D and E) included in the path indicated by the dashed line with the movable waveguide 150 (movable waveguide 150 indicated by arrow F) included in the path indicated by the dashed line, the quantum bits of the two quantum bit elements 20 indicated by arrows A and B are input to the beam splitter 30 indicated by arrow C and entangled. When the movable waveguide 150 indicated by arrows D and E and the movable waveguide 150 indicated by arrow F are in a disconnected state, no quantum bits are output from the two quantum bit elements 20 indicated by arrows A and B to the movable waveguide 150, and therefore no entanglement occurs.

[0022] <Optical directional coupler 100> 4 is a plan view showing an example of the configuration of an optical directional coupler 100. The optical directional coupler 100 includes a first insulating section 110, a second insulating section 120, a first electrode 115A, a second electrode 125A, a third electrode 115B, a fourth electrode 125B, a first capacitor 110C, a second capacitor 120C, a spring (elastic member) 130, a metal film 140, and a movable waveguide 150. The first capacitor 110C has a first electrode 115A and a second electrode 125A. The second capacitor 120C has a third electrode 115B and a fourth electrode 125B. In addition to these components, the optical directional coupler 100 also includes a drive control section that controls the drive of the movable waveguide 150; the drive control section will be described later with reference to the accompanying drawings.

[0023] The optical directional coupler 100 excluding the movable waveguide 150 constitutes an electronic component 100A of the embodiment. Specifically, the electronic component 100A includes a first insulating portion 110, a second insulating portion 120, a first electrode 115A, a second electrode 125A, a third electrode 115B, a fourth electrode 125B, a first capacitor 110C, a second capacitor 120C, a spring 130, and a metal film 140. The optical directional coupler 100 and the electronic component 100A are realized by MEMS.

[0024] The first insulating part 110, the second insulating part 120, the spring 130, and the movable waveguide 150 are, for example, integrally fabricated by micro-machining an insulator such as silicon (Si), alumina (Al2O3), or silicon carbide (SiC) for fabricating a MEMS.

[0025] 4 shows waveguides 10A and 10B in addition to the optical directional coupler 100. The waveguide 10A is an example of a first waveguide, and the waveguide 10B is an example of a second waveguide. The optical directional coupler 100 is an optical switch having a movable waveguide 150 as a movable part, and can be switched between a connected state in which the waveguides 10A and 10B are connected, and a disconnected state in which the waveguides 10A and 10B are not connected.

[0026] Here, the optical directional coupler 100 will be described using Fig. 5 and Fig. 6 in addition to Fig. 4. Fig. 5 is a diagram showing an example of the configuration of the first insulating section 110, the second insulating section 120, the spring 130, and the movable waveguide 150 of the optical directional coupler 100. Fig. 6 is a diagram showing an example of the configuration of the cross sections taken along the lines AA and BB in Fig. 4. In Figs. 4 to 6, an xyz coordinate system indicated by lowercase letters is defined and described. The direction parallel to the x axis (x direction), the direction parallel to the y axis (y direction), and the direction parallel to the z axis (z direction) are perpendicular to each other. Furthermore, a planar view refers to a view in the xy plane.

[0027] 5, the first insulating portion 110 has a plate-shaped base portion 111 and a plurality of protrusions 112 protruding in the -y direction from the surface of the base portion 111 on the -y direction side. The thickness of the base portion 111 in the z direction is constant throughout the base portion 111. The plurality of protrusions 112 protrude from the base portion 111 in a comb-teeth shape and are an example of first comb-teeth portions.

[0028] The thickness in the z direction of the multiple protrusions 112 is equal to the thickness in the z direction of the base 111, and the positions in the z direction of the multiple protrusions 112 are equal to the positions in the z direction of the base 111. The multiple protrusions 112 extend in the z direction to positions between the surface of the base 111 on the +z direction side and the surface of the base 111 on the −z direction side.

[0029] The leaf spring portion 132 of the spring 130 is connected to the side surface of the base portion 111 on the ±x direction side. The first insulating portion 110 is fixedly provided by being fixed to a substrate (not shown), for example.

[0030] As shown in Fig. 5, the second insulating part 120 faces the first insulating part 110 and is provided so as to be movable relative to the first insulating part 110 so that the distance between the second insulating part 120 and the first insulating part 110 can be changed. As shown in Fig. 5, the second insulating part 120 has a plate-shaped base part 121 and a plurality of protrusions 122 that protrude in the +y direction from the surface of the base part 121 on the +y direction side. In addition, a movable waveguide 150 is attached to the -y direction side of the base part 121 of the second insulating part 120. Therefore, the second insulating part 120 moves in the y direction together with the movable waveguide 150 relative to the first insulating part 110.

[0031] The thickness of base 121 in the z direction is constant throughout base 121. For example, the thickness of base 121 in the z direction is equal to the thickness of base 111 of first insulating part 110 in the z direction, and the position of base 121 in the z direction is equal to the position of base 111 in the z direction.

[0032] The plurality of protrusions 122 protrude in a comb-teeth shape from the base 121 and are an example of second comb-teeth portions. A leaf spring portion 132 of a spring 130 is connected to the side surface of the base 121 on the ±x direction side.

[0033] The thickness in the z direction of the multiple protrusions 122 is equal to the thickness in the z direction of the base 121, and the positions in the z direction of the multiple protrusions 122 are equal to the positions in the z direction of the base 121. The multiple protrusions 122 extend in the z direction to positions between the surface of the base 121 on the +z direction side and the surface of the base 121 on the −z direction side.

[0034] The multiple protrusions 122 face the multiple protrusions 112 of the first insulating portion 110 in the y direction, and the position of each protrusion 122 in the x direction is shifted relative to the position of each protrusion 112 in the x direction. The widths in the x direction and the lengths in the y direction of the multiple protrusions 122 are equal to the widths in the x direction and the lengths in the y direction of the multiple protrusions 112. When the second insulating portion 120 moves in the +y direction relative to the first insulating portion 110, the multiple protrusions 122 nest among the multiple protrusions 112. At this time, the multiple protrusions 112 do not come into contact with the multiple protrusions 122. In this way, the multiple protrusions 122 are arranged facing the multiple protrusions 112 in a nested manner. When the second insulating portion 120 moves in the +y direction relative to the first insulating portion 110, the distance between the first insulating portion 110 and the second insulating portion 120 decreases.

[0035] Note that, here, a configuration will be described in which the first insulating part 110 is fixed and the second insulating part 120 is provided so as to be movable relative to the first insulating part 110, but both the first insulating part 110 and the second insulating part 120 may be movable so as to approach each other in the y direction. The second insulating part 120 only needs to face the first insulating part 110 and be movable relative to the first insulating part 110 so that the distance between it and the first insulating part 110 can be changed.

[0036] 4 and 6(A), the first electrode 115A is provided on the surface on the +z direction side of the protrusion 112 (see FIGS. 5 and 6), the side surface on the +x direction side of the protrusion 112, and the side surface on the -x direction side of the protrusion 112. The first electrode 115A is further formed on the side surface on the -y direction side of the protrusion 112, the side surface on the -y direction side of the base 111 (the side surface parallel to the xz plane between the protrusions 112), and a portion of the surface on the +z direction side of the base 111 along the edge on the -y direction side.

[0037] The first electrode 115A is formed on the remaining protrusions 112 (see FIG. 5) excluding some of the protrusions 112 on the +x direction side. In FIG. 4, as an example, the first electrode 115A is formed on the outer surfaces of six of the nine protrusions 112 on the -x direction side. The first electrode 115A may also be formed on the surface of the protrusion 112 on the -z direction side. As an example, such a first electrode 115A can be produced by forming wiring made of a transparent conductor (such as indium tin oxide) on the surfaces of the base 111 and the protrusions 112 using a lift-off process.

[0038] 6B, the terminal 115A1 is provided on the surface of the base 111 on the +z direction side. The terminal 115A1 extends from the end of the first electrode 115A on the +y direction side to the end of the base 111 on the +y direction side.

[0039] A voltage is applied to the first electrode 115A from the drive control section. When the first electrode 115A is set to the ground potential and a negative voltage is applied to the terminal 142, the second electrode 125A and the movable waveguide 150 move.

[0040] Similar to the first electrode 115A, the second electrode 125A (see FIG. 4) is provided on the surface on the +z direction side of the protrusion 122 (see FIG. 5), the side surface on the +x direction side of the protrusion 122, the side surface on the -x direction side of the protrusion 122, and the side surface on the +y direction side of the protrusion 122. The second electrode 125A is further formed on the side surface on the +y direction side of the base 121 (the side surface parallel to the xz plane between the protrusions 122) and the surface on the +z direction side of the base 121. The second electrode 125A is held at ground potential (0 V).

[0041] The second electrode 125A is formed on the outer surfaces of the remaining protrusions 122 (see FIG. 5), excluding some of the protrusions 122 on the +x-direction side. In FIG. 4, as an example, the second electrode 125A is formed on the outer surfaces of seven of the ten protrusions 122 on the -x-direction side. The second electrode 125A may also be formed on the surface of the protrusion 122 on the -z-direction side. As an example, such a second electrode 125A can be produced by forming wiring made of a transparent conductor (such as indium tin oxide) on the surfaces of the base 121 and the protrusions 122 using a lift-off process.

[0042] Similar to the first electrode 115A, the third electrode 115B is provided on the surface on the +z direction side of the protrusion 112, the side surface on the +x direction side of the protrusion 112, and the side surface on the -x direction side of the protrusion 112. The third electrode 115B is further formed on the side surface on the -y direction side of the protrusion 112, the side surface on the -y direction side of the base 111 (the side surface parallel to the xz plane between the protrusions 112), and a portion of the surface on the +z direction side of the base 111 along the edge on the -y direction side.

[0043] The third electrode 115B is formed on the remaining protrusions 112 (see FIG. 5) excluding the protrusions 112 on which the first electrode 115A is formed. In FIG. 4, as an example, the third electrode 115B is formed on the outer surfaces of three of the nine protrusions 112 on the +x-direction side. The third electrode 115B may also be formed on the surface of the protrusion 112 on the -z-direction side. As an example, such a third electrode 115B can be produced by forming wiring made of a transparent conductor (such as indium tin oxide) on the surfaces of the base 111 and the protrusions 112 using a lift-off process.

[0044] Like the terminal 115A1, the wiring 115B1 is provided on the surface of the first insulating portion 110 on the +z direction side. The wiring 115B1 is connected to the edge of the third electrode 115B on the +y direction side and extends to the edge of the first insulating portion 110 on the +y direction side. The parasitic inductance of the wiring 115B1 is used as part of the inductance component of the resonant circuit including the second capacitor 120C. Because the parasitic inductance of the wiring 115B1 increases as the length of the wiring 115B1 increases, the wiring 115B1 may be, for example, a meandering wiring. The wiring 115B1 can be fabricated by forming a wiring made of a transparent conductor (such as indium tin oxide) on the surface of the base portion 111 on the +z direction side using a lift-off process.

[0045] Similar to the second electrode 125A, the fourth electrode 125B is provided on the surface on the +z direction side of the protrusion 122 (see FIG. 5), the side surface on the +x direction side of the protrusion 122, the side surface on the -x direction side of the protrusion 122, and the side surface on the +y direction side of the protrusion 122. The fourth electrode 125B is further formed on the side surface on the +y direction side of the base 121 (the side surface parallel to the xz plane between the protrusions 122) and the surface on the +z direction side of the base 121. The fourth electrode 125B is held at ground potential (0 V).

[0046] The fourth electrode 125B is formed on the outer surfaces of the remaining protrusions 122 (see FIG. 5 ), excluding the protrusion 122 on which the second electrode 125A is formed. In FIG. 4 , as an example, the fourth electrode 125B is formed on the outer surfaces of three of the ten protrusions 122 on the +x-direction side. The fourth electrode 125B may also be formed on the surface of the protrusion 122 on the −z-direction side. For example, such a fourth electrode 125B can be fabricated by forming wiring made of a transparent conductor (such as indium tin oxide) on the surfaces of the base 121 and the protrusions 122 using a lift-off process. The first electrode 115A, the second electrode 125A, the third electrode 115B, and the fourth electrode 125B do not have to protrude in a comb-like shape and may be, for example, flat electrodes.

[0047] Here, dimensions related to the comb teeth included in the third electrode 115B and the fourth electrode 125B will be described using FIG. 7. FIG. 7 is a diagram illustrating dimensions related to the third electrode 115B and the fourth electrode 125B. The third electrode 115B and the fourth electrode 125B form the second capacitor 120C. FIG. 7 shows the third electrode 115B and the fourth electrode 125B in a state where the second insulating section 120 (see FIGS. 4 and 5) is closest to the first insulating section 110 (see FIGS. 4 and 5).

[0048] The length of the teeth of the third electrode 115B and the fourth electrode 125B in the y direction is, for example, 2 μm, and the distance (gap) between the teeth of the third electrode 115B and the fourth electrode 125B in the x direction is, for example, 0.5 μm.

[0049] 4, the first capacitor 110C has a first electrode 115A and a second electrode 125A. The first capacitor 110C is used to detect the voltage between the first electrode 115A and the second electrode 125A (inter-electrode voltage) in position control when moving the movable waveguide 150 in the optical directional coupler 100. This will be described in detail later.

[0050] In first capacitor 110C, first electrode 115A and second electrode 125A are comb-shaped and have a large surface area, so that a larger capacitance can be obtained compared to a configuration having two flat electrodes. Note that first electrode 115A and second electrode 125A are not limited to comb-shaped electrodes, and may be two flat electrodes or may have other shapes.

[0051] The second capacitor 120C has a third electrode 115B and a fourth electrode 125B. The second capacitor 120C is used to detect the inter-electrode distance used when correcting the voltage between the first electrode 115A and the second electrode 125A (inter-electrode voltage) in position control when moving the movable waveguide 150 in the optical directional coupler 100. This will be described in detail later.

[0052] In second capacitor 120C, third electrode 115B and fourth electrode 125B are comb-shaped and have large surface areas, so a larger capacitance can be obtained compared to a configuration having two flat electrodes. Note that third electrode 115B and fourth electrode 125B are not limited to comb-shaped electrodes and may be two flat electrodes or may have other shapes, but it is preferable that they have the same shape as first electrode 115A and second electrode 125A.

[0053] The comb-teeth shape of the third electrode 115B and the fourth electrode 125B of the second capacitor 120C is the same as the comb-teeth shape of the first electrode 115A and the second electrode 125A of the first capacitor 110C. Furthermore, the first electrode 115A and the third electrode 115B are formed on the first insulating section 110, and the second electrode 125A and the fourth electrode 125B are formed on the second insulating section 120. Therefore, the inter-electrode distance between the first electrode 115A and the second electrode 125A of the first capacitor 110C (the inter-electrode distance of the first capacitor 110C) is the same as the inter-electrode distance between the third electrode 115B and the fourth electrode 125B of the second capacitor 120C (the inter-electrode distance of the second capacitor 120C). The inter-electrode distance of the first capacitor 110C and the inter-electrode distance of the second capacitor 120C are always equal even when the second insulating section 120 and the movable waveguide 150 move relative to the first insulating section 110 in the y direction.

[0054] Note that, although a configuration in which the third electrode 115B and the fourth electrode 125B of the second capacitor 120C and the first electrode 115A and the second electrode 125A of the first capacitor 110C have the same comb-tooth shape and inter-electrode distance will be described here, the present invention is not limited to this configuration. Even if the second insulating section 120 and the movable waveguide 150 move in the y direction relative to the first insulating section 110, the first electrode 115A, the second electrode 125A, the third electrode 115B, and the fourth electrode 125B may have any shape as long as the ratio between the inter-electrode distance of the first capacitor 110C and the inter-electrode distance of the second capacitor 120C is always constant.

[0055] The springs 130 are provided one on each side of the first insulating part 110 and the second insulating part 120 in the x direction. Here, the spring 130 on the -X direction side is referred to as spring 130A, and the spring 130 on the +X direction side is referred to as spring 130B. No metal film 140 is formed on spring 130A, but a metal film 140 is formed on spring 130B. Hereinafter, when there is no need to particularly distinguish between springs 130A and 130B, they will be referred to as springs 130.

[0056] The springs 130A and 130B each have a base 131 and a leaf spring portion 132. The base 131 moves together with the movable waveguide 150. The leaf spring portion 132 of the spring 130A extends in the +x direction from both ends of the base 131 in the y direction and has a tip connected to the side surfaces of the first insulating portion 110 and the second insulating portion 120 on the -X direction side. The width of the leaf spring portion 132 in the z direction is equal to the thickness of the first insulating portion 110 and the second insulating portion 120 in the z direction, and the thickness of the leaf spring portion 132 in the y direction is very thin, as shown in FIGS. 4 and 5 . The leaf spring portion 132 of the spring 130B extends in the -x direction from both ends of the base 131 in the y direction and has a tip connected to the side surfaces of the first insulating portion 110 and the second insulating portion 120 on the +X direction side.

[0057] 4 and 5, springs 130A and 130B are in a natural state where leaf spring portion 132 extends straight in the x direction relative to base portion 131 and is not deformed, and is not subjected to any external force. When a voltage is applied to first electrode 115A, a force acts to attract second electrode 125A (and second insulating portion 120) in the +y direction relative to first electrode 115A (and first insulating portion 110). At this time, leaf spring portion 132 generates an elastic force (restoring force) that attempts to return second electrode 125A (and second insulating portion 120) in the -y direction, but the Coulomb force that attracts first electrode 115A (and first insulating portion 110) in the +y direction is greater, so first electrode 115A (and first insulating portion 110) moves in the +y direction.

[0058] When voltage is no longer applied to the first electrode 115A, the elastic force (restoring force) of the plate spring portion 132 causes the plate spring portion 132 to return to a state in which it is stretched straight in the x direction relative to the base portion 131, and the second electrode 125A (and the second insulating portion 120) returns to the position shown in Figure 4.

[0059] The metal film 140 has a wiring portion 141 and a terminal 142. The wiring portion 141 is formed on the surface of the base portion 131 of the spring 130B and on the surface of the leaf spring portion 132 of the spring 130B. The terminal 142 is formed on the end portion of the surface on the +z direction side of the first insulating portion 110 on the +x direction side. One end of the wiring portion 141 is connected to the terminal 142, and the other end of the wiring portion 141 is connected to the fourth electrode 125B.

[0060] The parasitic inductance of the metal film 140 is used as part of the inductance component of the resonant circuit including the second capacitor 120C. This will be described in detail later. The film thickness of the metal film 140 is very thin, and the width of the wiring portion 141 in the y and z directions is very narrow, so the resistance value of the wiring portion 141 is relatively large. For this reason, the metal film 140 may be made of the same metal as the metal film of the fourth electrode 125B, or may be formed of a superconducting film.

[0061] The movable waveguide 150 is connected to the −y direction side of the second insulating part 120. Here, as an example, the movable waveguide 150 has a curved shape that matches the step between the surfaces of the waveguides 10A and 10B on the +y direction sides.

[0062] Here, the operation of the movable waveguide 150 will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a diagram showing the optical directional coupler 100 in an on state, and Fig. 9 is a diagram showing the optical directional coupler 100 in an off state.

[0063] The optical directional coupler 100 is in the on state when no voltage is applied to the first electrode 115A, the leaf spring portion 132 is not deformed as shown in Fig. 8, and the movable waveguide 150 is in contact with the surfaces of the waveguides 10A and 10B on the +y direction side. Because the optical directional coupler 100 is in the on state when no voltage is applied to the first electrode 115A, the optical directional coupler 100 shown in Figs. 8 and 9 is, for example, a normally-on optical directional coupler 100.

[0064] The on state of the optical directional coupler 100 is a connected state in which the movable waveguide 150 connects the waveguides 10A and 10B. In the connected state, light L1 propagating through the waveguide 10A propagates to the waveguide 10B via the movable waveguide 150. Therefore, an optical path P1 through which light L1 can propagate is generated in the waveguide 10A, the movable waveguide 150, and the waveguide 10B.

[0065] When the optical directional coupler 100 is in the off state, a voltage is applied to the first electrode 115A, the leaf spring portion 132 is deformed as shown in FIG. 9, and the movable waveguide 150 is not in contact with the surfaces of the waveguides 10A and 10B on the +y direction side. When the optical directional coupler 100 is in the off state, a voltage is applied to the first electrode 115A, and the second electrode 125A (and the second insulating portion 120) is attracted in the +y direction relative to the first electrode 115A (and the first insulating portion 110). When the optical directional coupler 100 is in the off state, the movable waveguide 150 does not connect the waveguides 10A and 10B. In the unconnected state, the optical path P1 shown in FIG. 8 does not occur, and the light L1 propagating through the waveguide 10A does not propagate to the waveguide 10B.

[0066] <Resonant circuit> Fig. 10 is a diagram showing an example of an equivalent circuit 160 of the optical directional coupler 100. In addition to the equivalent circuit 160, Fig. 10 also shows a measuring unit 170. The equivalent circuit 160 has a first capacitor 110C, a second capacitor 120C, terminals 161, 162, and 163, an adjustment capacitor 164, and an inductor unit 165. The first capacitor 110C and the second capacitor 120C are represented by the symbol for a variable capacitor because their capacitance changes with a change in the distance between their electrodes.

[0067] Terminal 161 is connected to second electrode 125A and fourth electrode 125B. Therefore, the potential of terminal 161 is 0V. Terminal 162 is connected to first electrode 115A. Terminal 163 is connected to second electrode 125A via adjustment capacitor 164 and inductor section 165. V1 is the voltage of terminal 162 relative to the voltage of terminal 161. V2 is the voltage of terminal 163 relative to the voltage of terminal 161.

[0068] The adjustment capacitor 164 has a capacitance for adjusting the resonant frequency of the resonant circuit described below. The adjustment capacitor 164 may be provided as needed, and may not be provided if not required. The adjustment capacitor 164 may be, for example, a chip capacitor or a capacitor obtained by patterning a metal film.

[0069] The inductor section 165 represents, as an electronic component, the total parasitic inductance of the wiring 115B1 and the metal film 140. The inductance of the inductor section 165 is equal to the total parasitic inductance of the wiring 115B1 and the metal film 140.

[0070] The resonant circuit of the optical directional coupler 100 includes a second capacitor 120C, an adjustment capacitor 164, and an inductor section 165. If the total capacitance of the second capacitor 120C and the adjustment capacitor 164 is C and the inductance of the inductor section 165 is L, the resonant frequency f of the resonant circuit is given by f=1 / {2π×(LC) 1 / 2}.

[0071] The measuring unit 170 is connected to the terminals 161 and 163. The measuring unit 170 sweeps the frequency to detect the resonant frequency and measures the inter-electrode distance D2 of the second capacitor 120C. A network analyzer can be used as the measuring unit 170.

[0072] When the optical directional coupler 100 is in the off state, the resonant frequency of the resonant circuit including the second capacitor 120C is, for example, 1.00 GHz, and when the optical directional coupler 100 is in the on state, the resonant frequency of the resonant circuit including the second capacitor 120C is, for example, 1.0065 GHz. Because the resonant frequency changes in this way, the inter-electrode distance D2 of the second capacitor 120C can be measured.

[0073] <Drive control unit 180> 11 is a diagram showing an example of the drive control unit 180. In addition to the drive control unit 180, Fig. 11 shows a first capacitor 110C and a controller 190. The drive control unit 180 has a voltage generation unit 181 and a displacement amount detection unit 182.

[0074] An input terminal of voltage generating unit 181 is connected to controller 190 and an output terminal of displacement amount detecting unit 182, and an output terminal of voltage generating unit 181 is connected to first electrode 115A of first capacitor 110C and an input terminal of displacement amount detecting unit 182. In other words, the output terminal of voltage generating unit 181 is connected to terminal 162 in the equalization circuit of FIG.

[0075] Based on a command input from the controller 190 and a control amount FB input from the displacement amount detection unit 182, the voltage generation unit 181 generates and outputs a voltage to be applied to the first electrode 115A.

[0076] The displacement amount detection unit 182 generates and outputs a control amount FB based on the inter-electrode distance D2 and the output of the voltage generation unit 181.

[0077] The controller 190 outputs a target value according to whether the optical directional coupler 100 is turned on or off. Therefore, feedback control can be performed based on the target value according to whether the optical directional coupler 100 is turned on or off.

[0078] As described above, the control amount FB generated using the inter-electrode distance D2 of the second capacitor 120C is input to the voltage generating unit 181, and the voltage generating unit 181 generates a voltage corrected based on the control amount FB and applies it to the first electrode 115A.

[0079] Therefore, it is possible to provide the electronic component 100A, the optical directional coupler 100, and the method for controlling the optical directional coupler 100, which are capable of moving the movable waveguide 150 with high precision.

[0080] Furthermore, the parasitic inductance of the wiring 115B1 connected to the third electrode 115B and the metal film 140 formed on the spring 130 connected to the second insulating section 120 constitutes an inductor portion included in the resonant circuit. Therefore, the resonant circuit can be realized using the wiring 115B1 and the metal film 140, and high integration can be achieved. Note that the inductor portion may be either the wiring 115B1 or the metal film 140.

[0081] Furthermore, when the metal film 140 is made of a superconducting film, the resistance of the wiring portion 141 of the metal film 140 can be significantly reduced, the Q value of the resonant circuit increases, and the resonant frequency can be easily measured.

[0082] The first insulating section 110 has a protrusion 112 that constitutes a first comb-tooth section, and the first electrode 115A and the third electrode 115B are provided on the first comb-tooth section. The second insulating section 120 has a protrusion 122 that constitutes a second comb-tooth section that faces the first comb-tooth section in a nested manner, and the second electrode 125A and the fourth electrode 125B are provided on the second comb-tooth section. This allows the capacitance of the first capacitor 110C including the first electrode 115A and the third electrode 115B and the capacitance of the second capacitor 120C including the second electrode 125A and the fourth electrode 125B to be increased.

[0083] The above description has been given as an example of a normally-on optical directional coupler 100. However, the optical directional coupler 100 may be a normally-off optical directional coupler 100 that is in an off state when no voltage is applied to the first electrode 115A.

[0084] The above describes a form in which electronic component 100A is used in optical directional coupler 100, but since electronic component 100A can detect the position of second insulating portion 120 with high accuracy, it may also be used in devices other than optical directional coupler 100.

[0085] <First Modification> Fig. 12 is a plan view showing an example of the configuration of an optical directional coupler 100M1 of a first modified example of the embodiment. Here, differences from the optical directional coupler 100 shown in Fig. 4 will be described. Here, the same components as those of the optical directional coupler 100 shown in Fig. 4 are designated by the same reference numerals, and their description will be omitted.

[0086] The optical directional coupler 100M1 is obtained by integrating the second electrode 125A and the fourth electrode 125B of the optical directional coupler 100 shown in FIG. 4 into an electrode 125, and adding a metal film 140A.

[0087] Metal film 140A has wiring portion 141 and terminal 142, and is formed on spring 130A. Metal film 140B is similar to metal film 140 shown in Fig. 4. The parasitic inductance of metal film 140A, like metal film 140B, is used as part of the inductance component of a resonant circuit including second capacitor 120C.

[0088] Electrode 125 in Fig. 12 has second electrode 125A and fourth electrode 125B. Second electrode 125A of electrode 125 in Fig. 12 is a portion of electrode 125 that, together with first electrode 115A, constitutes first capacitor 110C. Fourth electrode 125B of electrode 125 in Fig. 12 is a portion of electrode 125 that, together with third electrode 115B, constitutes second capacitor 120C.

[0089] 4 are both held at 0 V, the second electrode 125A and the fourth electrode 125B of the optical directional coupler 100 function in the same way even when integrated as the electrode 125. Therefore, the optical directional coupler 100M1 of the first modification can move the movable waveguide 150 with high precision, similar to the optical directional coupler 100. Note that the optical directional coupler 100M1 may have a configuration that does not include the metal film 140A.

[0090] <Second Modification> 13 and 14 are plan views showing an example of the configuration of an optical directional coupler 100M2 of a second modified example of the embodiment. The optical directional coupler 100M2 is a normally-off optical directional coupler. FIG. 13 shows the optical directional coupler 100M2 in the off state, and FIG. 14 shows the optical directional coupler 100M2 in the on state. Here, differences from the optical directional coupler 100 shown in FIG. 4 will be described. Here, components similar to those of the optical directional coupler 100 shown in FIG. 4 are designated by the same reference numerals, and their description will be omitted.

[0091] The optical directional coupler 100M2 differs from the optical directional coupler 100 shown in FIG. 4 in that the leaf spring portions 132 of the springs 130A and 130B are connected only to the second insulating portion 120, that the optical directional coupler 100M2 is a normally-off type, and that the end of the movable waveguide 150 on the −y direction side extends linearly in the x direction. The end of the movable waveguide 150 on the −y direction side extends linearly in the x direction because the waveguides 10A and 10B are positioned at the same position in the y direction. Because the first insulating portion 110 is fixed, the coupler is in an off state (disconnected state) as shown in FIG. 13 when no voltage is applied to the first electrode 115A. Furthermore, when a voltage (negative voltage) is applied to the first electrode 115A, the movable waveguide 150 moves in the −y direction and comes into contact with the waveguides 10A and 10B as shown in FIG. 14, thereby turning on (connected state). A voltage is applied to first electrode 115A so that second electrode 125A moves in a direction away from first electrode 115A, so the polarity of the applied voltage is opposite to that of the normally-on type.

[0092] When the optical directional coupler 100M2 is on, as shown in Fig. 14, the springs 130A and 130B are deformed, generating an elastic force (restoring force) that returns the movable waveguide 150 in the +y direction. As described above, the normally-off type and the normally-on type differ in the presence or absence and polarity of voltage applied to the first electrode 115A, but the basic principle is the same. Also, even in a configuration in which the leaf spring portions 132 of the springs 130A and 130B are connected only to the second insulating portion 120, the operation of moving the movable waveguide 150 in the y direction is the same as that of the optical directional coupler 100 shown in Fig. 4.

[0093] Therefore, it is possible to provide an electronic component, an optical directional coupler 100M2, and a method for controlling the optical directional coupler 100M2 that can move the movable waveguide 150 with high precision. Note that the electronic component of the second modified example has a configuration in which the movable waveguide 150 is omitted from the optical directional coupler 100M2.

[0094] <Third Modification> FIG. 15 is a plan view showing an example of the configuration of an optical directional coupler 100M3 according to a third modified example of the embodiment. The optical directional coupler 100M3 is a normally-off optical directional coupler. The optical directional coupler 100M3 has a configuration in which the positions of the first insulating section 110, the first electrode 115A, and the third electrode 115B and the second insulating section 120, the second electrode 125A, and the fourth electrode 125B of the optical directional coupler 100M2 according to the second modified example shown in FIG. 13 are interchanged in the y direction, and the positional relationship between the first electrode 115A, the second electrode 125A, and the spring 130A and the third electrode 115B, the fourth electrode 125B, and the spring 130B is interchanged in the x direction. In addition, in the optical directional coupler 100M3, the movable waveguide 150 is attached to the base 131 of the spring 130B, away from the second insulating section 120.

[0095] When no voltage is applied to the first electrode 115A, it is in an off state (disconnected state) as shown in Fig. 15. When a voltage (negative voltage) is applied to the first electrode 115A, the movable waveguide 150 moves in the -y direction and comes into contact with the waveguides 10A and 10B, thereby turning it on (connected state).

[0096] Therefore, it is possible to provide an electronic component, an optical directional coupler 100M3, and a method for controlling the optical directional coupler 100M3 that can move the movable waveguide 150 with high precision. The electronic component of the second modification has a configuration in which the movable waveguide 150 is omitted from the optical directional coupler 100M2.

[0097] The above describes exemplary embodiments of the electronic component, optical directional coupler, and method for controlling an optical directional coupler of the present disclosure. However, the present disclosure is not limited to the specifically disclosed embodiments, and various modifications and variations are possible without departing from the scope of the claims. [Explanation of symbols]

[0098] 1. Quantum computers 10, 10X, 10Y, 10S waveguide 20 qubit elements 30 Beam Splitter 40 Coupler 50 Photodetector 100, 100M1, 100M2, 100M3 optical directional coupler 110 First insulating section 120 Second insulating section 115A 1st electrode 125A 2nd electrode 115B 3rd electrode 125B 4th electrode 125 electrode 110C 1st Capacitor 120C Second Capacitor 130 Spring 140, 140A, 140B metal film 150 Movable Waveguide

Claims

1. A first insulating portion; a second insulating portion facing the first insulating portion and movable relative to the first insulating portion so that a distance between the second insulating portion and the first insulating portion changes; a first capacitor having a first electrode provided on the first insulating portion and a second electrode provided on the second insulating portion; a second capacitor having a third electrode provided on the first insulating portion and a fourth electrode provided on the second insulating portion; an inductor connected to the second capacitor to form a resonant circuit; Including, electronic components.

2. 2. The electronic component according to claim 1, wherein the inductor is a wiring connected to the third electrode or a metal portion formed on an elastic member connected to the second insulating portion.

3. 3. The electronic component according to claim 1, wherein the inductor is made of a superconductor.

4. the first electrode and the third electrode have a comb-tooth shape, The electronic component according to claim 1 , wherein the second electrode and the fourth electrode have a comb-like shape that faces the first electrode and the third electrode in a nested manner, respectively.

5. The electronic component according to claim 1 , wherein the second electrode and the fourth electrode are connected to each other.

6. A first insulating portion; a second insulating portion facing the first insulating portion and movable relative to the first insulating portion so that a distance between the second insulating portion and the first insulating portion changes; a first capacitor having a first electrode provided on the first insulating portion and a second electrode provided on the second insulating portion; a second capacitor having a third electrode provided on the first insulating portion and a fourth electrode provided on the second insulating portion; an inductor connected to the second capacitor to form a resonant circuit; a movable waveguide provided in the second insulating part, which is switchable, in accordance with movement of the second insulating part, between a connected state in which the first waveguide and the second waveguide, or the first waveguide or the second waveguide and a quantum bit element, are optically connected, and a non-connected state in which the first waveguide and the second waveguide are not optically connected; An optical directional coupler comprising:

7. 7. The optical directional coupler according to claim 6, wherein the inductor is a metal portion formed on a wiring connected to the third electrode or a spring connected to the second insulating portion.

8. 8. The optical directional coupler according to claim 6, wherein the inductor is made of a superconductor.

9. the first electrode and the third electrode have a comb-tooth shape, 9. The optical directional coupler according to claim 6, wherein the second electrode and the fourth electrode have a comb-like shape that faces the first electrode and the third electrode in a nested manner, respectively.

10. 10. The optical directional coupler according to claim 6, further comprising a feedback control unit that calculates an inter-electrode distance of the second capacitor from a resonant frequency of the resonant circuit obtained by sweeping the frequency of a signal applied to the resonant circuit, and that uses the calculated inter-electrode distance to feedback-control the voltage applied to the first capacitor.

11. 11. The optical directional coupler according to claim 6, wherein the second electrode and the fourth electrode are connected to each other.

12. A first insulating portion; a second insulating portion facing the first insulating portion and movable relative to the first insulating portion so that a distance between the second insulating portion and the first insulating portion changes; a first capacitor having a first electrode provided on the first insulating portion and a second electrode provided on the second insulating portion; a second capacitor having a third electrode provided on the first insulating portion and a fourth electrode provided on the second insulating portion; an inductor connected to the second capacitor to form a resonant circuit; a movable waveguide provided in the second insulating part, which is switchable, in accordance with movement of the second insulating part, between a connected state in which the first waveguide and the second waveguide, or the first waveguide or the second waveguide and a quantum bit element, are optically connected, and a non-connected state in which the first waveguide and the second waveguide are not optically connected; A method for controlling an optical directional coupler, comprising: A method for controlling an optical directional coupler, comprising: calculating an inter-electrode distance of the second capacitor from a resonant frequency of the resonant circuit obtained by sweeping the frequency of a signal applied to the resonant circuit; and feedback-controlling a voltage applied to the first capacitor using the calculated inter-electrode distance.

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