Coaxial cable of dilution refrigerator based on superconductor, dilution refrigerator and superconducting quantum computing equipment

Abstract

The invention provides a coaxial cable of a dilution refrigerator based on a superconductor, the dilution refrigerator and superconducting quantum computing equipment. The dilution refrigerator at least comprises a first temperature layer, a second temperature layer, a third temperature layer and a fourth temperature layer, the coaxial cable comprises a conductor layer, an insulating layer and a first shielding layer, and the first shielding layer is arranged on the insulating layer with a first thickness; the coaxial cable includes: a first coaxial cable section disposed in the first temperature layer; the second coaxial cable section is arranged in the second temperature layer; the third coaxial cable section is arranged in the third temperature layer; the fourth coaxial cable section is arranged in the fourth temperature layer; wherein the first thicknesses and materials of the first shielding layers of the first coaxial cable section, the second coaxial cable section, the third coaxial cable section and the fourth coaxial cable section are determined according to a preset combination mode.

Description

Technical Field

[0001] The present invention relates to the technical field of dilution refrigerators, and in particular to a coaxial cable of a dilution refrigerator based on a superconductor, a dilution refrigerator and a superconducting quantum computing device. Background Art

[0002] Superconducting quantum computing is a physical implementation method of quantum computing that uses the quantum properties of superconducting materials. Experiments in superconducting quantum computing must be conducted at ultra-low temperatures (such as less than 20mK). Dilution refrigerators are key equipment for providing ultra-low cooling for superconducting quantum computing. The dilution refrigerator is equipped with multiple stages of cold plates, which are one of the core components of the dilution refrigerator and are used to maintain a low-temperature environment and control the temperature. Superconducting quantum chips and various electronic devices (such as attenuators, etc.) are arranged on the cold plates, and signals are transmitted between each stage of the cold plates through coaxial cables.

[0003] At present, the coaxial cable generally used in dilution refrigerators is a copper-nickel coaxial cable. The outermost layer of the copper-nickel coaxial cable is a copper-nickel alloy with a thickness of 0.86 mm and a thermal conductivity of 30.7 W / (m · k ).

[0004] However, the inventors found that the copper-nickel coaxial cable in the dilution refrigerator will produce spatial crosstalk due to the influence of spatial electromagnetic interference. Although the spatial crosstalk of the existing copper-nickel coaxial cable has been controlled to the order of one thousandth of the original signal, this level of spatial crosstalk will still have a certain impact on the calculation accuracy of superconducting quantum computing.

[0005] Therefore, the inventors believe that how to improve the spatial electromagnetic shielding capability of the coaxial cable in the dilution refrigerator is a technical problem that needs to be solved.

[0006] The contents of the background technology section are merely the technologies known to the public and do not necessarily represent the existing technologies in the field. Summary of the invention

[0007] According to one aspect of the present invention, the present invention provides a coaxial cable for a dilution refrigerator based on a superconductor. The dilution refrigerator includes at least a first temperature layer, a second temperature layer, a third temperature layer and a fourth temperature layer, and the coaxial cable includes a conductor layer, an insulating layer and a first shielding layer, and the first shielding layer is arranged on the insulating layer with a first thickness. The coaxial cable includes: a first coaxial cable segment, which is arranged in the first temperature layer; a second coaxial cable segment, which is arranged in the second temperature layer; a third coaxial cable segment, which is arranged in the third temperature layer; and a fourth coaxial cable segment, which is arranged in the fourth temperature layer. Among them, the first thickness and material of the first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are determined according to a preset combination method.

[0008] According to some embodiments of the present invention, the coaxial cable further comprises: a second shielding layer, which is disposed on the first shielding layer with a second thickness, and the second shielding layer is a superconductor material. The first shielding layer is made of copper-nickel material, the second shielding layer is a tin-immersion coating or a tin-spray coating, and the second thickness ranges from 100nm to 10um; or the first shielding layer is made of copper-nickel material, the second shielding layer is a vapor-deposited niobium layer, and the second thickness ranges from 100nm to 10um.

[0009] According to some embodiments of the present invention, the preset combination includes a first combination, wherein the first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is made of copper-nickel. The first thickness of the first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is a first characteristic thickness.

[0010] According to some embodiments of the present invention, the preset combination includes a second combination, and the second combination is: the first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is made of beryllium copper. The first thickness of the first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is the second characteristic thickness.

[0011] According to some embodiments of the present invention, the preset combination includes a third combination, and the third combination is: the first shielding layer of the first coaxial cable segment is made of copper-nickel, and the first thickness of the first shielding layer of the first coaxial cable segment is a first characteristic thickness. The first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment are made of copper-nickel, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is a second characteristic thickness. A second shielding layer having a second thickness is further provided on the first shielding layer of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment, and the second shielding layer is a tin-immersion plating layer or a tin-spraying plating layer, and the second thickness ranges from 100nm to 10um. Or the preset combination includes a fourth combination, and the fourth combination is: the first shielding layer of the first coaxial cable segment is made of copper-nickel, and the first thickness of the first shielding layer of the first coaxial cable segment is the first characteristic thickness. The first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is made of copper-nickel, and the first thickness of the first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is the second characteristic thickness. A second shielding layer with a second thickness is also arranged on the first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment, and the second shielding layer is a vapor-deposited niobium layer, and the second thickness ranges from 100nm to 10um.

[0012] According to some embodiments of the present invention, the preset combination includes a fifth combination, and the fifth combination is: the first shielding layer of the first coaxial cable segment is made of beryllium copper, and the first thickness of the first shielding layer of the first coaxial cable segment is the second characteristic thickness. The first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment are made of copper-nickel, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is the second characteristic thickness; the first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment are further provided with a second shielding layer having a second thickness, the second shielding layer being a tin-immersion coating or a tin-spray coating, and the second thickness ranges from 100nm to 10um. Or the preset combination includes the sixth combination, which is: the first shielding layer of the first coaxial cable segment is made of beryllium copper, and the first thickness of the first shielding layer of the first coaxial cable segment is the second characteristic thickness; the first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are made of copper-nickel, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is the second characteristic thickness. A second shielding layer with a second thickness is also provided on the first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment, and the second shielding layer is a vapor-deposited niobium layer, and the second thickness ranges from 100nm to 10um.

[0013] According to some embodiments of the present invention, the preset combination includes a seventh combination, and the seventh combination is: the first shielding layer of the first coaxial cable segment is made of copper-nickel, and the first thickness of the first shielding layer of the first coaxial cable segment is a first characteristic thickness. The first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment are made of niobium-titanium, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment are a second characteristic thickness.

[0014] According to some embodiments of the present invention, the preset combination includes an eighth combination, and the eighth combination is: the first shielding layer of the first coaxial cable segment is made of beryllium copper, and the first thickness of the first shielding layer of the first coaxial cable segment is the second characteristic thickness. The first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment are made of niobium titanium, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is the second characteristic thickness.

[0015] According to another aspect of the present invention, the present invention further provides a dilution refrigerator. The dilution refrigerator comprises the coaxial cable as described above.

[0016] According to another aspect of the present invention, the present invention further provides a superconducting quantum computing device, which includes the dilution refrigerator as described above.

[0017] Beneficial Effects

[0018] The present invention can determine the first thickness of each first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment through a preset combination, and determine the material of the corresponding first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment.

[0019] With such an arrangement, the present invention can make the first thickness and material of the first shielding layer of the coaxial cable segments arranged in different temperature layers in the dilution refrigerator different. In this way, based on the characteristics of the cold plate, the spatial crosstalk signals of different magnitudes can be suppressed without affecting the thermal conductivity as much as possible, thereby achieving the overall spatial crosstalk suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram showing the structure of a coaxial cable of a dilution refrigerator according to an embodiment of the present invention;

[0022] Figure 2 A cross-sectional schematic diagram of a coaxial cable according to an embodiment of the present invention is shown.

[0023] Description of reference numerals:

[0024] Conductor layer 10 ; insulation layer 20 ; first shielding layer 30 ; second shielding layer 40 . DETAILED DESCRIPTION

[0025] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present invention will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0026] The described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other modes, components, materials, devices, etc. may be adopted. In these cases, known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0027] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products or devices.

[0028] The terms "first", "second" and the like in the specification, claims and the above drawings of the present invention are used to distinguish different objects rather than to describe a specific order.

[0029] The technical solution of the present invention is described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] Superconductors have the Meissner effect, that is, when a superconductor is cooled below the superconducting transition temperature (Tc), the magnetic induction intensity inside the superconductor is zero, and it can exhibit complete diamagnetism.

[0031] The inventors found that because superconductors have the Meissner effect, superconductors can be used in coaxial cables of dilution refrigerators in ultra-low temperature working environments. Superconductor-based coaxial cables can completely eliminate resistance and repel spatial electromagnetic fields under specific low temperature conditions, thereby improving the spatial electromagnetic shielding capability of coaxial cables in dilution refrigerators and achieving spatial crosstalk suppression. For example, the London penetration depth of a superconductor is approximately 50-500nm, which means that it can attenuate the spatial electromagnetic field to 1 / e of its surface.

[0032] According to one aspect of the present invention, the present invention provides a coaxial cable for a dilution refrigerator based on a superconductor. The coaxial cable provided by the present invention has good spatial electromagnetic shielding capability and can suppress spatial crosstalk.

[0033] Figure 1 A schematic structural diagram of a coaxial cable of a dilution refrigerator according to an embodiment of the present invention is shown.

[0034] According to example embodiments, a dilution refrigerator includes at least a first temperature layer, a second temperature layer, a third temperature layer, and a fourth temperature layer.

[0035] The dilution refrigerator may include five cold plates, such as Figure 1 The first cold plate, the second cold plate, the third cold plate, the fourth cold plate and the fifth cold plate are shown in Figure 1. There are different temperature layers between adjacent cold plates of the first cold plate, the second cold plate, the third cold plate, the fourth cold plate and the fifth cold plate.

[0036] Exemplarily, the first cold plate may be a 50K cold plate, the second cold plate may be a 4K cold plate, the third cold plate may be a 600mK distillation layer cold plate, the fourth cold plate may be a 100mK cold plate, and the fifth cold plate may be a 10mK mixing chamber cold plate.

[0037] Figure 2 A cross-sectional schematic diagram of a coaxial cable according to an embodiment of the present invention is shown.

[0038] like Figure 2 As shown, the coaxial cable comprises a conductor layer 10, an insulating layer 20 and a first shielding layer 30. The first shielding layer 30 is disposed on the insulating layer 20 with a first thickness d1.

[0039] For example, the conductor layer 10 can be composed of a single or multiple copper wires for signal transmission. The insulating layer 20 is located outside the conductor layer 10 and is generally made of plastic or other insulating materials to isolate the inner and outer conductors to prevent leakage current. The first shielding layer 30 is generally a mesh structure woven of metal wires for shielding interference signals.

[0040] According to an example embodiment, Figure 1 As shown, the coaxial cable may include a first coaxial cable segment L1, a second coaxial cable segment L2, a third coaxial cable segment L3, and a fourth coaxial cable segment L4.

[0041] The first coaxial cable L1 is arranged in a first temperature layer formed by the first cold plate and the second cold plate, the second coaxial cable L2 is arranged in a second temperature layer formed by the second cold plate and the third cold plate, the third coaxial cable L3 is arranged in a third temperature layer formed by the third cold plate and the fourth cold plate, and the third coaxial cable L4 is arranged in a fourth temperature layer formed by the fourth cold plate and the fifth cold plate.

[0042] Exemplarily, the coaxial cable segments between adjacent cold plates may be connected by a preset wiring method to form a coaxial cable as a whole.

[0043] According to an example embodiment, the first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1, the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 may be different. Also, the materials of the first shielding layer 30 of the first coaxial cable segment L1, the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 may be different.

[0044] For example, the first thickness d1 of the first shielding layer 30 may be 0.86 mm or 3.58 mm. The material of the first shielding layer 30 includes, but is not limited to, copper-nickel material, beryllium-copper material, and niobium-titanium material.

[0045] By means of the preset combination, the first thickness d1 of each first shielding layer of the first coaxial cable segment L1, the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4 can be determined, and the material of the corresponding first shielding layer 30 of the first coaxial cable segment L1, the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4 can be determined.

[0046] In this way, the present invention can make the first thickness d1 and material of the first shielding layer 30 of the coaxial cable segment arranged in different temperature layers in the dilution refrigerator different. In this way, based on the characteristics of the cold plate, the spatial crosstalk signal of different magnitudes can be suppressed without affecting the thermal conductivity as much as possible, thereby achieving the overall spatial crosstalk suppression.

[0047] Alternatively, if Figure 2 As shown, the coaxial cable may further include a second shielding layer 40. The second shielding layer 40 is disposed on the first shielding layer 30 with a second thickness d2.

[0048] Optionally, the first shielding layer 30 is made of copper-nickel material, the second shielding layer 40 is an immersion tin plating layer or a spray tin plating layer, and the second thickness d2 is in the range of 100nm-10um.

[0049] According to the experimental data of the present invention, the thermal conductivity of tin is 60W / (m·K), and the second thickness d2 of the immersion tin coating or the spray tin coating is less than one percent of the first thickness d1 of the copper-nickel first shielding layer, so the heat conductivity per unit volume can be suppressed to a large extent. At this time, the superconducting transition temperature is 3.72K. After the superconducting transition, since the resistance of the immersion tin coating is 0 and has the Meissner effect, the spatial electromagnetic crosstalk can be suppressed.

[0050] Optionally, the first shielding layer 30 is made of copper-nickel, the second shielding layer 40 is a vapor-deposited niobium layer, and the second thickness d2 is in the range of 100 nm-10 um.

[0051] The evaporated niobium layer may be obtained by evaporating on the first shielding layer 30 by magnetron sputtering.

[0052] According to the experimental data of the present invention, niobium has a lower thermal conductivity, such as 53.7W / (m·K). The second thickness d2 of the evaporated niobium layer is in the range of several hundred nanometers or even micrometers, so the heat conductivity per unit volume can be suppressed to a large extent. At this time, the superconducting transition temperature is 9.2K. Based on the characteristics of niobium superconductors, spatial electromagnetic crosstalk can also be suppressed.

[0053] Optionally, the preset combination method includes a first combination method, and the first combination method is:

[0054] The first shielding layer 30 of the first coaxial cable segment L1, the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4 is made of copper-nickel. The first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1, the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4 is a first characteristic thickness.

[0055] For example, the first characteristic thickness is 3.58 mm.

[0056] For example, the thickness of the copper-nickel coaxial cable in the prior art is 0.86 mm, while the first thickness d1 of the copper-nickel first shielding layer in the present invention is 3.58 mm.

[0057] According to the experimental data of the present invention, the resistivity of the 3.58mm copper-nickel coaxial cable is 0.27Ω / m@300K. The resistivity of the 0.86mm copper-nickel coaxial cable is 1.56Ω / m@300K. For example, the first combination can refer to Table (1):

[0058] combination <![CDATA[L1]]> <![CDATA[L2]]> <![CDATA[L3]]> <![CDATA[L4]]> 1 3.58mm Copper Nickel 3.58mm Copper Nickel 3.58mm Copper Nickel 3.58mm Copper Nickel

[0059] Table (1)

[0060] The present invention can reduce the resistivity of the coaxial cable by adjusting the thickness of the copper-nickel coaxial cable, thereby reducing the introduction of electromagnetic crosstalk.

[0061] It can be understood here that the skin effect can show that the thicker the metal layer, the stronger the electromagnetic shielding ability. In the single coaxial cable experiment of the present invention, compared with the 0.86mm copper-nickel coaxial cable, the 3.58mm copper-nickel coaxial cable can be seen to have a significant electromagnetic crosstalk suppression effect, such as noise can be reduced by about 3dB.

[0062] According to the exemplary embodiment, an initial coaxial cable segment L0 may be further provided between the room temperature layers, but the material setting of the initial coaxial cable segment L0 and the first coaxial cable segment L1 is the same, so the initial coaxial cable segment L0 and the first coaxial cable segment L1 may be regarded as the same cable segment, and the present invention is not limited to this.

[0063] Optionally, the preset combination method includes a second combination method, and the second combination method is:

[0064] The first shielding layer 30 of the first coaxial cable segment L1, the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4 is made of beryllium copper. The first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1, the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4 is the second characteristic thickness.

[0065] Exemplarily, the second characteristic thickness may be 0.86 mm.

[0066] For the second combination, please refer to Table (2):

[0067] combination <![CDATA[L1]]> <![CDATA[L2]]> <![CDATA[L3]]> <![CDATA[L4]]> 2 0.86mm Beryllium Copper 0.86mm Beryllium Copper 0.86mm Beryllium Copper 0.86mm Beryllium Copper

[0068] Table (2)

[0069] For example, according to the experimental data of the present invention, it can be shown that the resistivity of the first beryllium copper shielding layer is 0.39Ω / m@300K, and the first beryllium copper shielding layer can also reduce the introduction of electromagnetic crosstalk. In the low-temperature comparison experiment of the present invention, in the case of all 0.86mm copper-nickel coaxial cables, the electromagnetic crosstalk signal strength is -56dB. In the case of the second combination provided by the present invention, the electromagnetic crosstalk signal is suppressed below the system noise, and the system noise is -80.7dB at this time.

[0070] Optionally, the preset combination method includes a third combination method, and the third combination method is:

[0071] The first coaxial cable segment L1 is made of copper-nickel, and the first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1 is the first characteristic thickness. The first shielding layers of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 are made of copper-nickel, and the first thickness d1 of the first shielding layer 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 is the second characteristic thickness.

[0072] A second shielding layer 40 with a second thickness d2 is disposed on the first shielding layer 30 of the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4. The second shielding layer 40 is a tin-immersion coating or a tin-spray coating, and the second thickness d2 ranges from 100 nm to 10 um.

[0073] Taking the first characteristic thickness as 3.58 mm and the second characteristic thickness as 0.86 mm as an example, the third combination can refer to Table (3):

[0074]

[0075] Table (3)

[0076] According to an exemplary embodiment, the tin plating layer may be an immersion tin plating layer or a spray tin plating layer, and the present invention is not limited thereto.

[0077] According to the experimental data of the present invention, it can be shown that, taking the tin-spraying coating as an example, the thickness of the tin-spraying coating is 3.2275um, in the low temperature comparison experiment of the present invention, when all the cables are 0.86mm copper-nickel coaxial cables, the electromagnetic crosstalk signal strength is -56dB. In the case of the third combination provided by the present invention, the electromagnetic crosstalk signal is suppressed below the system noise, and the system noise is about -81.4dB at this time.

[0078] Optionally, the preset combination method includes a fourth combination method, and the fourth combination method is:

[0079] The first shielding layer 30 of the first coaxial cable segment L1 is made of copper-nickel, and the first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1 is the first characteristic thickness. The first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 are made of copper-nickel, and the first thickness d1 of the first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 is the second characteristic thickness.

[0080] A second shielding layer 40 with a second thickness d2 is disposed on the first shielding layer 30 of the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4. The second shielding layer 40 is a vapor-deposited niobium layer, and the second thickness d2 ranges from 100 nm to 10 um.

[0081] Taking the first characteristic thickness as 3.58 mm and the second characteristic thickness as 0.86 mm as an example, the fourth combination can refer to Table (4):

[0082]

[0083] Table (4)

[0084] Based on the same principle as the third combination method, this setting can suppress electromagnetic crosstalk signals, and the suppression of spatial electromagnetic crosstalk is better than traditional copper-nickel cables.

[0085] Optionally, the preset combination method includes a fifth combination method, and the fifth combination method is:

[0086] The first shielding layer 30 of the first coaxial cable segment L1 is made of beryllium copper, and the first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1 is the second characteristic thickness. The first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 are made of copper-nickel, and the first thickness d1 of the first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 is the second characteristic thickness.

[0087] A second shielding layer 40 with a second thickness d2 is disposed on the first shielding layer 30 of the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4. The second shielding layer 40 is a tin-immersion coating or a tin-spray coating, and the second thickness d2 ranges from 100 nm to 10 um.

[0088] For the fifth combination, please refer to Table (5):

[0089]

[0090] Table (5)

[0091] Based on the same principle as the third combination method, this setting can suppress electromagnetic crosstalk signals, and the suppression of spatial electromagnetic crosstalk is better than traditional copper-nickel cables.

[0092] Optionally, the preset combination method includes a sixth combination method, and the sixth combination method is:

[0093] The first shielding layer 30 of the first coaxial cable segment L1 is made of beryllium copper, and the first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1 is the second characteristic thickness. The first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 are made of copper-nickel, and the first thickness d1 of the first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 is the second characteristic thickness.

[0094] A second shielding layer 40 with a second thickness d2 is disposed on the first shielding layer 30 of the second coaxial cable segment L2, the third coaxial cable segment L3 and the fourth coaxial cable segment L4. The second shielding layer 40 is a vapor-deposited niobium layer, and the second thickness d2 ranges from 100 nm to 10 um.

[0095] Taking the second characteristic thickness of 0.86 mm as an example, the sixth combination can refer to Table (6):

[0096]

[0097] Table (6)

[0098] Based on the same principle as the third combination method, this setting can suppress electromagnetic crosstalk signals, and the suppression of spatial electromagnetic crosstalk is better than traditional copper-nickel cables.

[0099] Optionally, the preset combination method includes a seventh combination method, and the seventh combination method is:

[0100] The first shielding layer 30 of the first coaxial cable segment L1 is made of copper-nickel, and the first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1 is the first characteristic thickness. The first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 are made of niobium-titanium, and the first thickness d1 of the first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 is the second characteristic thickness.

[0101] Taking the first characteristic thickness as 3.58 mm and the second characteristic thickness as 0.86 mm as an example, the seventh combination can refer to Table (7):

[0102] combination <![CDATA[L1]]> <![CDATA[L2]]> <![CDATA[L3]]> <![CDATA[L4]]> 7 3.58mm Copper Nickel 0.86mm Niobium Titanium 0.86mm Niobium Titanium 0.86mm Niobium Titanium

[0103] Table (7)

[0104] In the low temperature comparison experiment of the present invention, when all the cables are 0.86mm copper-nickel coaxial cables, the electromagnetic crosstalk signal strength is -56dB. In the case of the seventh combination provided by the present invention, the electromagnetic crosstalk signal is suppressed below the system noise, and the system noise is about -75.9dB.

[0105] Optionally, the preset combination method includes an eighth combination method, and the eighth combination method is:

[0106] The first shielding layer 30 of the first coaxial cable segment L1 is made of beryllium copper, and the first thickness d1 of the first shielding layer 30 of the first coaxial cable segment L1 is the second characteristic thickness. The first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 are made of niobium titanium, and the first thickness d1 of the first shielding layers 30 of the second coaxial cable segment L2, the third coaxial cable segment L3, and the fourth coaxial cable segment L4 is the second characteristic thickness.

[0107] For the seventh combination, please refer to Table (8):

[0108] combination <![CDATA[L1]]> <![CDATA[L2]]> <![CDATA[L3]]> <![CDATA[L4]]> 8 3.58mm Copper Nickel 0.86mm Niobium Titanium 0.86mm Niobium Titanium 0.86mm Niobium Titanium

[0109] Table (8)

[0110] Based on the same principle as the first, third and seventh combination modes, such an arrangement can suppress electromagnetic crosstalk signals, and the suppression of spatial electromagnetic crosstalk is better than that of traditional copper-nickel cables.

[0111] According to another aspect of the present invention, the present invention further provides a dilution refrigerator. The dilution refrigerator comprises the coaxial cable as described above.

[0112] According to another aspect of the present invention, the present invention further provides a superconducting quantum computing device, which includes the dilution refrigerator as described above.

[0113] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions of the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A coaxial cable for a superconductor-based dilution refrigerator, characterized in that: The dilution refrigerator comprises at least a first temperature layer, a second temperature layer, a third temperature layer and a fourth temperature layer, the coaxial cable comprises a conductor layer, an insulating layer and a first shielding layer, and the first shielding layer is arranged on the insulating layer with a first thickness; The coaxial cable comprises: a first coaxial cable segment disposed in the first temperature layer; a second coaxial cable segment disposed in the second temperature layer; a third coaxial cable segment, disposed in the third temperature layer; a fourth coaxial cable segment disposed in the fourth temperature layer; The first thickness and material of the first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment are determined according to a preset combination.

2. The coaxial cable according to claim 1, characterized in that: The coaxial cable also includes: a second shielding layer, disposed on the first shielding layer with a second thickness, the second shielding layer being made of a superconductor material; Among them, the first shielding layer is made of copper-nickel material, the second shielding layer is a tin-immersion plating layer or a tin-spraying plating layer, and the second thickness ranges from 100nm to 10um; or the first shielding layer is made of copper-nickel material, the second shielding layer is a vapor-deposited niobium layer, and the second thickness ranges from 100nm to 10um.

3. The coaxial cable according to claim 1, characterized in that: The preset combination method includes a first combination method, and the first combination method is: The first shielding layers of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are made of copper-nickel; A first thickness of the first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is a first characteristic thickness.

4. The coaxial cable according to claim 1, characterized in that: The preset combination method includes a second combination method, and the second combination method is: The first shielding layers of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are made of beryllium copper; A first thickness of the first shielding layer of the first coaxial cable segment, the second coaxial cable segment, the third coaxial cable segment, and the fourth coaxial cable segment is a second characteristic thickness.

5. The coaxial cable according to claim 1, characterized in that: The preset combination method includes a third combination method, and the third combination method is: The first shielding layer of the first coaxial cable segment is made of copper-nickel, and the first thickness of the first shielding layer of the first coaxial cable segment is a first characteristic thickness; The first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are made of copper-nickel, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is a second characteristic thickness; A second shielding layer with a second thickness is further provided on the first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment, the second shielding layer is a tin-immersion coating or a tin-spray coating, and the second thickness ranges from 100 nm to 10 um; or The preset combination method includes a fourth combination method, and the fourth combination method is: The first shielding layer of the first coaxial cable segment is made of copper-nickel, and the first thickness of the first shielding layer of the first coaxial cable segment is a first characteristic thickness; The first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are made of copper-nickel, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is a second characteristic thickness; A second shielding layer with a second thickness is further provided on the first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment. The second shielding layer is a vapor-deposited niobium layer. The second thickness ranges from 100 nm to 10 um.

6. The coaxial cable according to claim 1, characterized in that: The preset combination method includes a fifth combination method, and the fifth combination method is: The first shielding layer of the first coaxial cable segment is made of beryllium copper, and the first thickness of the first shielding layer of the first coaxial cable segment is a second characteristic thickness; The first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are made of copper-nickel, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is a second characteristic thickness; A second shielding layer with a second thickness is further provided on the first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment, the second shielding layer is a tin-immersion coating or a tin-spray coating, and the second thickness ranges from 100 nm to 10 um; or The preset combination method includes a sixth combination method, and the sixth combination method is: The first shielding layer of the first coaxial cable segment is made of beryllium copper, and the first thickness of the first shielding layer of the first coaxial cable segment is a second characteristic thickness; The first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is made of copper-nickel, and the first thickness of the first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is a second characteristic thickness; a second shielding layer with a second thickness is also arranged on the first shielding layer of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment, the second shielding layer is a vapor-deposited niobium layer, and the second thickness ranges from 100nm to 10um.

7. The coaxial cable according to claim 1, characterized in that: The preset combination method includes a seventh combination method, and the seventh combination method is: The first shielding layer of the first coaxial cable segment is made of copper-nickel, and the first thickness of the first shielding layer of the first coaxial cable segment is a first characteristic thickness; The first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are made of niobium titanium, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is a second characteristic thickness.

8. The coaxial cable according to claim 1, characterized in that: The preset combination method includes an eighth combination method, and the eighth combination method is: The first shielding layer of the first coaxial cable segment is made of beryllium copper, and the first thickness of the first shielding layer of the first coaxial cable segment is a second characteristic thickness; The first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment are made of niobium titanium, and the first thickness of the first shielding layers of the second coaxial cable segment, the third coaxial cable segment and the fourth coaxial cable segment is a second characteristic thickness.

9. A dilution refrigerator, characterized in that: Comprising the coaxial cable as described in any one of claims 1-8.

10. A superconducting quantum computing device, characterized in that: Comprising the dilution refrigerator as claimed in claim 9.

Images