Irreversible circuit elements and quantum computers

Abstract

The present invention provides a non-reversible circuit element capable of sufficiently suppressing heat generation in an extremely low-temperature environment, and a quantum computer equipped with the same. [Solution] The irreversible circuit element 100 comprises a central conductor 10, a first loss layer 21 and a second loss layer 22 arranged outside the central conductor 10, and a first housing 41 and a second housing 42 arranged outside the first loss layer 21 and the second loss layer 22. The first loss layer 21 has a first magnetic material 25 and a first absorber 26, and the second loss layer 22 has a second magnetic material 27 and a second absorber 28. The central conductor 10 has first and second terminals for inputting and outputting signals, a region that overlaps with the first magnetic material 25 and the second magnetic material 27 when viewed from the thickness direction and extends between the first and second terminals, and a region that overlaps with the first absorber 26 and the second absorber 28 when viewed from the thickness direction, and irreversibly transmits signals between the first and second terminals. At least a portion of the central conductor 10 is a superconductor.

Description

[Technical Field]

[0001] This invention relates to a non-reversible circuit element and a quantum computer. [Background technology]

[0002] Irreversible circuit elements are elements that define the direction of transmission of high-frequency signals. Isolators and circulators are examples of irreversible circuit elements. Irreversible circuit elements are widely used in circuits where high-frequency signals are transmitted.

[0003] Non-reversible circuit elements are used in various applications where high-frequency signals are employed. For example, Patent Document 1 discloses an isolator with a usable bandwidth from several GHz to approximately 10 GHz.

[0004] Isolators are also used in quantum computers. Among the various types of quantum computers, the superconducting quantum computer, which is currently considered the most promising, requires isolators that function at extremely low temperatures in order to accurately measure qubits. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2023 / 238310 [Overview of the project] [Problems that the invention aims to solve]

[0006] The isolator is positioned closest to the qubit in the coldest part of the refrigerator within the superconducting quantum computer.

[0007] Since isolators achieve isolation properties by converting high-frequency signals into heat, heat generation is unavoidable. Therefore, in order to maintain an extremely low-temperature environment around the qubit, it is necessary to minimize the heat generated in the isolator.

[0008] However, the irreversible circuit element disclosed in Patent Document 1 is based on the structure of an isolator that functions at room temperature, and has the problem that it cannot sufficiently suppress heat generation in an extremely low-temperature environment.

[0009] The present invention has been made to solve these conventional problems, and aims to provide an irreversible circuit element that can sufficiently suppress heat generation in an extremely low temperature environment, and a quantum computer equipped with the same. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides the following means.

[0011] The irreversible circuit element according to this embodiment comprises a conductor, a loss layer disposed outside the conductor, and a housing disposed outside the loss layer. The loss layer has a magnetic material and an absorber. The conductor has a first terminal and a second terminal for inputting and outputting signals, a region that overlaps with the magnetic material and extends between the first and second terminals when viewed in the thickness direction, and a region that overlaps with the absorber when viewed in the thickness direction, and transmits the signal irreversibly between the first and second terminals. At least a portion of the conductor is a superconductor. [Effects of the Invention]

[0012] This invention provides a non-reversible circuit element that can sufficiently suppress heat generation in an extremely low-temperature environment, and a quantum computer equipped with the same. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view (part 1) of a non-reversible circuit element according to an embodiment of the present invention. [Figure 2] It is a plan view of a non-reversible circuit element according to an embodiment of the present invention. [Figure 3] It is a plan view of a loss layer and a mold of a non-reversible circuit element according to an embodiment of the present invention. [Figure 4] It is a plan view of an adhesive layer and a mold of a non-reversible circuit element according to an embodiment of the present invention. [Figure 5] It is a cross-sectional view (No. 2) of a non-reversible circuit element according to an embodiment of the present invention. [Figure 6] It is a plan view showing a state in which a loss layer of a non-reversible circuit element according to an embodiment of the present invention is divided into a plurality of fragments. [Figure 7] It is a plan view of a central conductor and a resonator of a non-reversible circuit element according to an embodiment of the present invention. [Figure 8] It is a plan view of a housing and a magnet of a non-reversible circuit element according to an embodiment of the present invention. [Figure 9] It is a table showing physical properties of various materials. [Figure 10] It is a schematic diagram of a quantum computer according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of a non-reversible circuit element and a quantum computer according to the present invention will be described with reference to the drawings. Note that the dimensional ratios of the respective components on each drawing do not necessarily match the actual dimensional ratios.

[0015] FIG. 1 is a cross-sectional view of a non-reversible circuit element 100 according to the present embodiment. The non-reversible circuit element 100 includes, for example, a central conductor 10, a first loss layer 21, a second loss layer 22, a first magnet 31, a second magnet 32, an upper housing 41 as a first housing, a lower housing 42 as a second housing, a resonator 50, a first mold 61, and a second mold 62. The non-reversible circuit element 100 functions as an isolator, for example.

[0016] Figure 2 is a plan view of the irreversible circuit element 100 according to this embodiment. In this specification, the direction from the first terminal T1 to the second terminal T2 of the central conductor 10 is defined as the x-direction, the direction perpendicular to the x-direction on the plane in which the central conductor 10 expands is defined as the y-direction, and the direction perpendicular to both the x-direction and the y-direction is defined as the z-direction. The thickness direction of each layer is an example of the z-direction. Furthermore, with respect to the z-direction, the side where the upper housing 41 exists is defined as upward, and the side where the lower housing 42 exists is defined as downward.

[0017] Figure 2 is a plan view of the irreversible circuit element 100, excluding the first loss layer 21, the first magnet 31, the upper housing 41, and the lower housing 42, from the top side, showing the central conductor 10, the second loss layer 22, and the second formwork 62. Figure 1 is a cross-sectional view showing a section cut along line AA in Figure 2.

[0018] Figure 3 is a plan view of the second loss layer 22 and the second formwork 62 from above, with the central conductor 10 removed from Figure 2. Figure 4 is a plan view of the second adhesive layer 72 and the second formwork 62, which will be described later, from above, with the second loss layer 22 removed from Figure 3. Figure 5 is a cross-sectional view showing a section cut along the BB line in Figure 2.

[0019] The first loss layer 21 and the second loss layer 22 are positioned outside the central conductor 10 and the resonator 50, respectively, so as to sandwich the central conductor 10 and the resonator 50 in the z direction. The first loss layer 21 comprises a first magnetic material 25 and a first absorber 26. The second loss layer 22 comprises a second magnetic material 27 and a second absorber 28. The shapes of the first loss layer 21 and the second loss layer 22 are substantially identical and symmetrical with respect to the central conductor 10 and the resonator 50. The first loss layer 21 is located between the central conductor 10 and the first magnet 31. The second loss layer 22 is located between the central conductor 10 and the second magnet 32.

[0020] The upper housing 41 and the lower housing 42 are positioned outside the first loss layer 21 and the second loss layer 22, respectively, so as to sandwich them in the z-direction. The upper housing 41 is sandwiched between the first magnet 31 and the first loss layer 21. The lower housing 42 is sandwiched between the second magnet 32 ​​and the second loss layer 22. The upper housing 41 or the lower housing 42 is conductive and, for example, grounded to a reference potential. The reference potential is, for example, ground.

[0021] As shown in Figure 1, the upper housing 41 has heat dissipation surfaces 41a and 41b that dissipate heat generated in the central conductor 10, the first loss layer 21, and the second loss layer 22. Similarly, the lower housing 42 has heat dissipation surfaces 42a and 42b that dissipate heat generated in the central conductor 10, the first loss layer 21, and the second loss layer 22. The heat dissipation surfaces 41a, 41b, 42a, and 42b are surfaces parallel to the xz plane.

[0022] The upper housing 41 is attached to a cryogenic plate inside a refrigerator (not shown) via heat dissipation surfaces 41a and 41b. Similarly, the lower housing 42 is attached to a cryogenic plate inside a refrigerator (not shown) via heat dissipation surfaces 42a and 42b.

[0023] The upper housing 41 and the lower housing 42 include a high thermal conductivity material having a thermal conductivity of 300 W / m·K or more at cryogenic temperatures of 4K or below. The high thermal conductivity material constituting the upper housing 41 and the lower housing 42 is, for example, one of the metals such as gold (Au), silver (Ag), copper (Cu), platinum (Pt), and palladium (Pd).

[0024] By configuring the upper housing 41 and lower housing 42 in this way, the irreversible circuit element 100 can maintain its thermal conductivity at extremely low temperatures, thereby improving heat dissipation and reducing Johnson noise (thermal noise). Consequently, the insertion loss of the irreversible circuit element 100 is improved, and when used in a quantum computer, it can contribute to the accurate measurement of qubits.

[0025] In particular, using copper with a purity of 4N (99.99%) or higher as the high thermal conductivity material constituting the upper housing 41 and lower housing 42 is preferable because it can effectively increase thermal conductivity at extremely low temperatures. As shown in Figure 9, copper with a purity of 4N exhibits a thermal conductivity of 330 W / m·K at 4K. Furthermore, copper with a purity higher than 4N, almost 100%, exhibits a thermal conductivity of 11800 W / m·K at 4K. In Figure 9, "solid" means almost 100% purity.

[0026] The upper housing 41 and the first loss layer 21 are bonded together with a first adhesive layer 71 made of an insulating adhesive. Similarly, the lower housing 42 and the second loss layer 22 are bonded together with a second adhesive layer 72 made of an insulating adhesive. Alternatively, only one of the pairs, either the upper housing 41 and the first loss layer 21, or the lower housing 42 and the second loss layer 22, may be bonded together with either the first adhesive layer 71 or the second adhesive layer 72.

[0027] As shown in Figure 6, at least one of the first loss layer 21 and the second loss layer 22 may be divided into multiple fragments due to impact or thermal expansion and contraction. In such cases, the first adhesive layer 71 or the second adhesive layer 72 can be used to fix these multiple fragments so as not to fall out from between the upper housing 41 and the lower housing 42.

[0028] Therefore, even if at least one of the first loss layer 21 and the second loss layer 22 cracks irregularly, the irreversible circuit element 100 can maintain its isolation characteristics.

[0029] The first adhesive layer 71 and the second adhesive layer 72 are 35 × 10 at cryogenic temperatures of 4K or below. -6 It has a coefficient of thermal expansion of 31 × 10⁻¹⁰ or less. For the first adhesive layer 71 and the second adhesive layer 72, for example, STYCAST 2850FT manufactured by Henkel can be suitably used. As shown in Figure 9, the coefficient of thermal expansion of STYCAST 2850FT is 31 × 10⁻¹⁰. -6 It is / K, and is particularly close to the coefficient of linear thermal expansion of metals such as aluminum (Al), copper, solder, and brass.

[0030] The first adhesive layer 71 and the second adhesive layer 72, which have a coefficient of thermal expansion close to that of metal, are less prone to peeling from the upper housing 41 and the lower housing 42, and have excellent adhesion to the upper housing 41 and the lower housing 42.

[0031] Furthermore, as shown in Figure 9, the thermal conductivity of STYCAST 2850FT is 1.47 W / m·K at 300K and 0.053 W / m·K at 4K. In contrast, the thermal conductivity of air is 0.026 W / m·K at 300K, and it is known to decrease even further at 4K, becoming about 1 / 10th of the thermal conductivity of STYCAST 2850FT at 4K.

[0032] Therefore, the first adhesive layer 71 and the second adhesive layer 72, which are made of a resin-based adhesive such as STYCAST 2850FT, can maintain higher thermal conductivity than air at extremely low temperatures of 4K or below without reducing adhesion at the interfaces with the upper housing 41, lower housing 42, first loss layer 21, and second loss layer 22, thereby improving the heat dissipation of the irreversible circuit element 100.

[0033] The first mold 61 and the second mold 62 are insulating molds provided between the upper housing 41 and the lower housing 42, and surround the first loss layer 21 and the second loss layer 22, respectively. For the first mold 61 and the second mold 62, Teflon (registered trademark) can be suitably used, for example.

[0034] As shown in Figure 5, a gap 63 is formed between the first mold 61 and the first loss layer 21 to store excess adhesive generated when the upper housing 41 and the first loss layer 21 are bonded together with the first adhesive layer 71. In other words, the first adhesive layer 71 is formed to extend between the first mold 61 and the first loss layer 21. Similarly, a gap 64 is formed between the second mold 62 and the second loss layer 22 to store excess adhesive generated when the lower housing 42 and the second loss layer 22 are bonded together with the second adhesive layer 72. In other words, the second adhesive layer 72 is formed to extend between the second mold 62 and the second loss layer 22.

[0035] The surface tension of the first adhesive layer 71 stored in the gap 63 prevents the first adhesive layer 71 from penetrating between the opposing surfaces of the first mold 61 and the first magnetic material 25 along the z-direction, between the opposing surfaces of the first mold 61 and the first absorber 26 along the z-direction, and between the opposing surfaces of the first magnetic material 25 and the first absorber 26 along the z-direction, excluding the portion of the gap 63.

[0036] Similarly, the surface tension of the second adhesive layer 72 stored in the gap 64 prevents the second adhesive layer 72 from penetrating between the opposing surfaces of the second mold 62 and the second magnetic material 27 along the z-direction, between the opposing surfaces of the second mold 62 and the second absorber 28 along the z-direction, and between the opposing surfaces of the second magnetic material 27 and the second absorber 28 along the z-direction, excluding the portion of the gap 64.

[0037] Therefore, by storing the first adhesive layer 71 and the second adhesive layer 72 in the gaps 63 and 64, the first magnetic material 25 and the first absorber 26, and the second magnetic material 27 and the second absorber 28 come into close contact with each other, thereby stabilizing the isolation characteristics of the irreversible circuit element 100.

[0038] Figure 7 is a plan view of the central conductor 10 and resonator 50 of the irreversible circuit element 100 according to this embodiment.

[0039] The central conductor 10 has a first terminal T1 and a second terminal T2 for inputting and outputting high-frequency signals. The first terminal T1 and the second terminal T2 are connected to external terminals.

[0040] The surfaces of the first terminal T1 and the second terminal T2 may be covered with a metal film of any of the following metals: nickel (Ni), tin, copper, silver, for example. For example, by plating these metals onto the surfaces of the first terminal T1 and the second terminal T2 to form a metal film 14, wettability, connection strength, and conductivity can be ensured when the first terminal T1 and the second terminal T2 are soldered to external terminals.

[0041] The central conductor 10 irreversibly transmits high-frequency signals between the first terminal T1 and the second terminal T2. "Irreversibly transmitting high-frequency signals" means that the signal propagation efficiency differs depending on the direction. For example, if the central conductor 10 propagates signals with low loss in the forward direction but hardly propagates signals in the reverse direction, it falls under the category of "irreversibly transmitting high-frequency signals." The propagation direction of high-frequency signals in the central conductor 10 is controlled by the first loss layer 21 and the second loss layer 22.

[0042] The high-frequency signal input from the first terminal T1 is transmitted to the second terminal T2 with low loss. The high-frequency signal input from the second terminal T2 is almost entirely absorbed by the first absorber 26 and the second absorber 28. In other words, very little high-frequency signal is transmitted from the second terminal T2 to the first terminal T1.

[0043] The central conductor 10 can be any metal that transmits high-frequency signals with high efficiency, such as aluminum, copper, silver, gold, stainless steel (SUS), or beryllium copper (BeCu). The central conductor 10 may also be a non-conductor or a conductor with high resistance (for example, phosphor bronze) plated with aluminum, copper, silver, gold, stainless steel, etc.

[0044] Alternatively, the central conductor 10 may be a superconductor that exhibits superconductivity at extremely low temperatures below 4K, such as aluminum, niobium (Nb), or tantalum (Ta). The central conductor 10 may also be a non-conductor or a conductor with high resistance (for example, phosphor bronze) plated with a superconductor such as aluminum, niobium, or tantalum.

[0045] In particular, using aluminum with a purity of 4N (99.99%) or higher as the superconductor constituting the central conductor 10 is preferable because it can reduce residual resistance and increase thermal conductivity. As shown in Figure 9, aluminum with a purity of 4N exhibits a thermal conductivity of 1600 W / m·K at 4K. Aluminum with a purity of 5N exhibits a thermal conductivity of 11000 W / m·K at 4K. Furthermore, aluminum with a purity higher than 5N, almost 100%, exhibits a thermal conductivity of 17000 W / m·K at 4K.

[0046] Since the central conductor 10, which is composed of at least a portion of a superconductor, exhibits near-zero resistance at extremely low temperatures and suppresses heat generation, the irreversible circuit element 100 can reduce Johnson noise (thermal noise). Therefore, because the insertion loss of the irreversible circuit element 100 is improved, it can contribute to the accurate measurement of qubits when used in a quantum computer.

[0047] The central conductor 10 has a first region 11 and a second region 12. The central conductor 10 may also have regions other than the first region 11 and the second region 12. The first region 11 is the region that overlaps with the first magnetic material 25 and the second magnetic material 27 when viewed from the z direction. The first region 11 extends from the first terminal T1 to the second terminal T2. The first region 11 is sandwiched between the first magnetic material 25 and the second magnetic material 27 in the z direction. The second region 12 is the region that overlaps with the first absorber 26 and the second absorber 28 when viewed from the z direction. The second region 12 is sandwiched between the first absorber 26 and the second absorber 28 in the z direction. The boundary between the first region 11 and the second region 12 coincides, for example, with the boundary between the first magnetic material 25 and the first absorber 26 when viewed from the z direction.

[0048] As shown in Figure 7, the central conductor 10 has a first connecting wire S1 and a second connecting wire S2 on its outer circumference when viewed from the z direction. The first connecting wire S1 and the second connecting wire S2 are wires that connect the first terminal T1 and the second terminal T2, respectively. The first connecting wire S1 and the second connecting wire S2 together form the outer circumference of the central conductor 10 when viewed from the z direction.

[0049] The first connecting line S1 is one side of the first region 11. The first connecting line S1 can be a straight line or a curve. In the example shown in Figure 7, the first connecting line S1 is a straight line parallel to the straight line L1 connecting the first terminal T1 and the second terminal T2.

[0050] The second connecting line S2 spans both the first region 11 and the second region 12. The second connecting line S2 has, for example, a first side S21 and a second side S22 that extend from the first region 11 to the second region 12, and a third side S23 that is one side of the second region 12. The first side S21, the second side S22, and the third side S23 may be straight lines or curves.

[0051] The resonator 50 confines a portion of the high-frequency signal propagating along the second connecting line S2 within a certain space. The resonator 50 is within the range of the high-frequency signal propagating along the second connecting line S2. The resonator 50 is connected, for example, to the central conductor 10. The resonator 50 and the central conductor 10 may be integrated. The resonator 50 is, for example, one or more protrusions projecting from the third side S23.

[0052] The resonator 50 shown in Figure 7 is a quarter-wavelength resonator. A quarter-wavelength resonator satisfies the following relationship (1).

[0053] L≦1 / 4f0(ε0μ0ε γ μ γ ) 1 / 2 ... (1)

[0054] In equation (1), L is the length of the quarter-wavelength resonator, f0 is the resonant frequency, ε0 ​​is the permittivity of vacuum, μ0 is the permeability of vacuum, and ε γ μ is the dielectric constant of the first absorber 26 and the second absorber 28, and γ is the permeability of the first absorber 26 and the second absorber 28. The resonator 50 confines the high-frequency signal when its length L satisfies the condition that it is an integer multiple of a quarter wavelength of the high frequency propagating along the second connecting line S2. Length L is the length of the resonator 50 in the direction of protrusion from the third side S23.

[0055] When viewed from the z-direction, the resonator 50 overlaps with the first absorber 26 and the second absorber 28. The resonator 50 is sandwiched between the first absorber 26 and the second absorber 28 in the z-direction.

[0056] The resonator 50 is made of a conductor. For example, the same material as the central conductor 10 can be used for the resonator 50.

[0057] The resonator 50 shown in Figure 7 is, for example, symmetric in the x-direction with respect to the center line CL1. The center line CL1 is a line that passes through the center of the straight line connecting the first terminal T1 and the second terminal T2 and is perpendicular to that straight line. A resonator 50 that is symmetric with respect to the center line CL1 is easy to form and offers excellent versatility.

[0058] The first magnetic material 25 and the first absorber 26 are located at different positions in the xy plane when viewed from the z direction. Similarly, the second magnetic material 27 and the second absorber 28 are located at different positions in the xy plane when viewed from the z direction. The first magnetic material 25 and the second magnetic material 27 are located in the z direction, overlapping with the first region 11 of the central conductor 10. The first magnetic material 25 and the second magnetic material 27 sandwich the first region 11 in the z direction. The first absorber 26 and the second absorber 28 are located in the z direction, overlapping with the second region 12 of the central conductor 10 and the resonator 50. The first absorber 26 and the second absorber 28 sandwich the second region 12 and the resonator 50 in the z direction.

[0059] The shape of the first magnetic material 25 and the second magnetic material 27 is not limited as long as they can cover the first region 11. The shape of the first absorber 26 and the second absorber 28 is not limited as long as they can cover the second region 12 and the resonator 50. For example, as shown in Figure 3, both the first magnetic material 25 and the first absorber 26 may have a rectangular shape when viewed from the z direction.

[0060] The high-frequency signal passing through the center conductor 10 is displaced to one side in the propagation direction and propagates by applying a DC magnetic field to the first magnetic body 25 and the second magnetic body 27. For example, the high-frequency signal input from the first terminal T1 is displaced near the first connection line S1 and propagates along the first connection line S1 to the second terminal T2. On the other hand, the high-frequency signal input to the second terminal T2 is displaced near the second connection line S2 and propagates along the second connection line S2 to the first terminal T1. At this time, the high-frequency signal input to the second terminal T2 is absorbed by the first absorber 26 and the second absorber 28 and greatly attenuated. Also, the high-frequency signal input to the second terminal T2 is trapped by the resonator 50, and the intensity of the high-frequency signal trapped by the resonator 50 is greatly attenuated.

[0061] The first magnetic body 25 and the second magnetic body 27 include a magnetic material. The first magnetic body 25 and the second magnetic body 27 may be conductors or insulators. The first magnetic body 25 and the second magnetic body 27 have, for example, soft magnetism. The first magnetic body 25 and the second magnetic body 27 are, for example, Co-based amorphous, ferrite, Fe 85 Si2B8P4Cu, Fe 86 AlB8P4Cu, Fe 78 Si9B 13 and include any selected from the group consisting of yttrium iron garnet (YIG). YIG is, for example, Y3Fe2(FeO4)3, Y3Fe5O 12 is.

[0062] The first magnetic body 25 and the second magnetic body 27 may be a mixture of magnetic particles and resin. The magnetic particles have, for example, iron, silicon steel (Fe-Si), permalloy (Ni-Fe), permenjoul (Fe-Co), sendust (Fe-Si-Al), electromagnetic stainless steel, amorphous iron-based alloy (Fe-B-C system, Fe-Co system), manganese zinc ferrite, nickel zinc ferrite, etc. The first magnetic body 25 and the second magnetic body 27 may be a mixture of ferrite particles and resin.

[0063] When dispersing magnetic materials in insulating materials (e.g., resin, rubber, paint, etc.), it is preferable that the volume ratio of the magnetic material be between 10% and 70%. If the volume ratio of the magnetic material is too low, the electromagnetic wave absorption capacity will be low. If the volume ratio of the magnetic material is too high, dispersion into the insulating material becomes difficult.

[0064] The first absorber 26 and the second absorber 28 include materials with a higher magnetic field loss rate than the first magnetic material 25 and the second magnetic material 27. The first absorber 26 and the second absorber 28 include, for example, any of those selected from the group consisting of iron, BN, conductive carbon, SiC, and Ni-based ferrite.

[0065] If the first loss layer 21 and the second loss layer 22 are conductors, an insulating layer is provided between the first loss layer 21 and the central conductor 10, and between the second loss layer 22 and the central conductor 10. A known insulating layer can be used.

[0066] The first magnet 31 and the second magnet 32 ​​sandwich the central conductor 10, the first loss layer 21, and the second loss layer 22 in the z direction. The first magnet 31 and the central conductor 10 sandwich the first loss layer 21 in the z direction. The second magnet 32 ​​and the central conductor 10 sandwich the second loss layer 22 in the z direction. The first magnet 31 and the second magnet 32 ​​apply a DC magnetic field to the first magnetic material 25 and the second magnetic material 27.

[0067] Figure 8 is a plan view of the lower housing 42 and the second magnet 32 ​​from above. The first magnet 31 and the second magnet 32 ​​are positioned to overlap with the first magnetic material 25 and the second magnetic material 27 when viewed from the z direction. Parts of the first magnet 31 and the second magnet 32 ​​may also overlap with the first absorber 26 and the second absorber 28 when viewed from the z direction.

[0068] The first magnet 31 and the second magnet 32 ​​are, for example, hard magnetic materials. The first magnet 31 and the second magnet 32 ​​may be insulators or conductors. The first magnet 31 and the second magnet 32 ​​include, for example, any of the following selected from the group consisting of insulating ferrite magnets, conductive rare earth magnets, TbFeCo, GdFeCo, SmFeCo, [Co / Pt] multilayer films, and [Co / Pd] multilayer films. If the first magnet 31 and the second magnet 32 ​​are conductors, the upper housing 41 and the lower housing 42 may be omitted.

[0069] The first magnet 31 and the second magnet 32 ​​are examples of magnetic field sources. The magnetic field source is not limited to the first magnet 31 and the second magnet 32, as long as it can apply a DC magnetic field to the first magnetic material 25 and the second magnetic material 27 via the upper housing 41 and the lower housing 42, respectively.

[0070] The irreversible circuit element 100 according to this embodiment has excellent isolation characteristics due to the presence of a resonator 50. The resonator 50 confines a portion of the high-frequency signal input from the second terminal T2 within the resonator 50, preventing the high-frequency signal input from the second terminal T2 from reaching the first terminal T1. The smaller the intensity of the high-frequency signal from the second terminal T2 to the first terminal T1, the higher the isolation characteristics of the irreversible circuit element 100.

[0071] The irreversible circuit element 100 according to this embodiment can be applied to, for example, a quantum computer. Figure 10 is a schematic diagram of a quantum computer according to this embodiment. The quantum computer 200 includes, for example, a quantum processor 201, irreversible circuit elements 202, 203, filters 204, 205, and an amplifier 206.

[0072] The quantum processor 201 performs quantum computation. The non-reversible circuit elements 202 and 203 distribute the qubit readout signals from the quantum processor 201. The non-reversible circuit element 202 is a circulator. The non-reversible circuit element 203 is an isolator. The non-reversible circuit element 100 according to this embodiment can be applied to the non-reversible circuit element 203. The amplifier 206 amplifies the readout signals.

[0073] For example, superconducting quantum computers operate at extremely low temperatures. Therefore, the quantum processor 201 and the irreversible circuit elements 202 and 203 are also placed in positions exposed to the extremely low-temperature environment. Maintaining a large volume of space in an extremely low-temperature environment is difficult, so miniaturization of the irreversible circuit elements 202 and 203 is required. The irreversible circuit element 100 according to this embodiment is small and has excellent heat dissipation, thus enabling high performance and stable operation of the quantum computer. [Explanation of Symbols]

[0074] 10 Central conductor 11 First area 12 Second area 14 Metal coating 21 1st loss layer 22 2nd loss layer 25 First magnetic body 26. First absorber 27 Second magnetic body 28. Second absorber 31 First Magnet 32 Second Magnet 41 Upper chassis 41a,41b Heat dissipation surface 42 Lower enclosure 42a,42b Heat dissipation surface 50 resonators 61 First formwork 62. Second formwork 63, 64 gaps 71 1st adhesive layer 72 Second adhesive layer 100 Non-reversible circuit elements 200 Quantum Computers 201 Quantum Processor 202,203 Non-reversible circuit element 204,205 filters 206 Amplifier S1 First connection line S2 Second connection line S21 First side S22, second side S23 Third side T1 First terminal T2 Second terminal

Claims

1. The device comprises a conductor, a loss layer disposed outside the conductor, and a housing disposed outside the loss layer. The loss layer comprises a magnetic material and an absorber. The conductor has a first terminal and a second terminal for inputting and outputting signals, a region that overlaps with the magnetic material when viewed in the thickness direction and extends between the first terminal and the second terminal, and a region that overlaps with the absorber when viewed in the thickness direction, and transmits the signal irreversibly between the first terminal and the second terminal. A non-reversible circuit element characterized in that at least a portion of the conductor is a superconductor.

2. The non-reversible circuit element according to claim 1, characterized in that the superconductor is Al with a purity of 99.99% or more.

3. The non-reversible circuit element according to claim 1, characterized in that the surfaces of the first terminal and the second terminal are coated with a metal film.

4. A quantum computer characterized by including an irreversible circuit element as described in any one of claims 1 to 3.

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