A method for preparing cables for quantum computers

Abstract

The present invention relates to the technical field of cable preparation, and particularly to a method for preparing a cable for a quantum computer, including: stretching out a niobium-titanium alloy wire; extruding and coating polytetrafluoroethylene onto the outer surface of the niobium-titanium alloy wire to obtain an inner conductor with an insulating layer; performing niobium electroplating on the inner wall of a stainless steel tube to obtain a target cable; when it is determined that the niobium electroplating of the outer conductor substrate does not meet the preset standard according to the niobium plating uniformity eigenvalue, reducing the current density; inserting the inner conductor with an insulating layer into a stainless steel tube that meets the preset standard, and drawing the stainless steel tube to obtain a target cable. When it is determined that the preparation of the target cable does not meet the preset standard according to the contact resistance evaluation value, secondly determining whether the preparation of the target cable meets the preset standard, or determining a corresponding adjustment strategy according to the niobium plating layer cracking eigenvalue; winding and packaging the target cable that meets the preset standard, improving the cable preparation efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of cable preparation, and particularly to a method for preparing a cable for a quantum computer. Background Art

[0002] A quantum computer is a completely new computer based on quantum theory, which is a physical device that performs high-speed mathematical and logical operations, stores, and processes quantum information in accordance with the laws of quantum mechanics.

[0003] A cable is a medium for signal transmission in a quantum computer, responsible for transmitting control signals and data signals from an external control circuit to qubits, and transmitting the calculation results of qubits back to an external device.

[0004] Niobium is a material with superconducting properties that can lose resistance at extremely low temperatures, enabling lossless transmission of electric current. This property makes niobium an ideal material for manufacturing superconducting cables. In a quantum computer, superconducting cables are used to connect qubits and control circuits to ensure accurate signal transmission. Since a quantum computer needs to operate at extremely low temperatures to maintain the stability of qubits, the thermal insulation performance of superconducting cables is also crucial. Due to its superconducting properties and good thermal insulation performance, niobium cables have become an essential component in quantum computers.

[0005] Chinese Patent Publication No.: CN114694893A discloses a method for preparing a superconducting cable for a quantum computer, which specifically includes: using an oxygen-free copper tube and an NbTi rod, obtaining a multi-core NbTi / Cu rod through a secondary tube-passing method, cold-drawing the multi-core NbTi / Cu rod to obtain a multi-core NbTi / Cu composite superconducting wire, and then removing Cu in the multi-core NbTi / Cu composite superconducting wire with an etching solution to obtain multiple first-level NbTi wires; selecting a single NbTi wire at the central part of multiple first-level NbTi wires for winding to obtain multiple second-level NbTi strands; braiding the multiple second-level NbTi strands around a single NbTi wire that has been subjected to insulation treatment; obtaining a superconducting cable material for a quantum computer. This method selects an NbTi / Cu superconducting multi-core rod material with an appropriate number of cores as the raw material, and prepares a superconducting cable material suitable for a quantum computer through techniques such as drawing and etching the core wire, wrapping with polytetrafluoroethylene tape, and braiding NbTi wires.

[0006] It can be seen that the above technical solution does not consider the influence of the uniformity of niobium plating on the quality of cable preparation, cannot judge the qualification of cable preparation based on the performance differences of cables, and cannot precisely control the drawing parameters and niobium electroplating parameters of the cable, resulting in low cable preparation efficiency. Summary of the Invention

[0007] To this end, the present invention provides a method for preparing a cable for a quantum computer, which is used to overcome the problems in the prior art that the influence of the uniformity of niobium plating on the quality of cable preparation is not considered, the qualification of cable preparation cannot be judged according to the performance differences of cables, and the drawing parameters and niobium electroplating parameters of the cable cannot be accurately controlled, resulting in low cable preparation efficiency.

[0008] To achieve the above object, the present invention provides a method for preparing a cable for a quantum computer, including:

[0009] Using a niobium-titanium alloy rod as the inner conductor material, and stretching the niobium-titanium alloy rod to obtain niobium-titanium alloy wires;

[0010] Extruding and coating polytetrafluoroethylene onto the outer surface of the niobium-titanium alloy wires to obtain an inner conductor with an insulating layer;

[0011] Coating the outer surface of a stainless steel tube with an insulating material, then placing it in an electroplating solution containing niobium ions, electroplating a niobium coating with a preset thickness on the inner wall of the stainless steel tube after applying a preset current density, removing the insulating material to obtain an outer conductor substrate, and measuring the thickness of the niobium coating to obtain a niobium plating uniformity characteristic value;

[0012] When it is determined that the niobium plating of the outer conductor substrate does not meet the preset standard according to the niobium plating uniformity characteristic value, reduce the current density;

[0013] Insert the inner conductor with an insulating layer into the outer conductor substrate that meets the preset standard, and draw the outer conductor substrate to a preset thickness to obtain a target cable, and measure the contact resistance value of the target cable to obtain a contact resistance evaluation value;

[0014] When it is determined that the preparation of the target cable does not meet the preset standard according to the contact resistance evaluation value, re-determine whether the preparation of the target cable meets the preset standard according to the surface characteristic value of the outer conductor substrate, or determine the corresponding adjustment strategy according to the niobium coating cracking characteristic value;

[0015] Wind up and package the target cable that meets the preset standard.

[0016] Further, the process of determining that the niobium plating of the outer conductor substrate does not meet the preset standard according to the niobium plating uniformity characteristic value includes:

[0017] Comparing the niobium plating uniformity characteristic value with a preset niobium plating uniformity characteristic value;

[0018] If the niobium plating uniformity characteristic value is greater than or equal to the preset niobium plating uniformity characteristic value, it is determined that the niobium plating of the outer conductor substrate does not meet the preset standard, and reduce the current density according to the difference between the preset niobium plating uniformity characteristic value and the niobium plating uniformity characteristic value;

[0019] The niobium plating uniformity characteristic value is the standard deviation of the thickness of the niobium coating.

[0020] Furthermore, several density adjustment methods are provided for the reduction of the current density, and each density adjustment method has a different reduction amplitude for the current density.

[0021] Furthermore, in response to the contact resistance evaluation value being greater than or equal to the first preset contact resistance threshold, it is determined that the preparation of the target cable does not meet the preset standard, where the contact resistance evaluation value is the ratio between the contact resistance value after bending and the initial contact resistance value.

[0022] Furthermore, when the contact resistance evaluation value is greater than or equal to the first preset contact resistance threshold and less than the second preset contact resistance threshold, it is determined again whether the preparation of the target cable meets the preset standard according to the surface characteristic value of the outer conductor substrate, and when the contact resistance evaluation value is greater than or equal to the second preset contact resistance threshold, the corresponding adjustment strategy is determined according to the niobium-plated layer cracking characteristic value.

[0023] Furthermore, it is determined that the preparation of the target cable does not meet the preset standard according to the comparison result that the surface characteristic value of the outer conductor substrate is greater than or equal to the preset surface characteristic threshold, and the drawing rate of the outer conductor substrate is reduced according to the difference between the surface characteristic value and the preset surface characteristic threshold;

[0024] The surface characteristic value is the ratio between the surface roughness of the outer conductor substrate and the preset surface roughness.

[0025] Furthermore, several rate adjustment methods are provided for the reduction of the drawing rate, and each rate adjustment method has a different reduction amplitude for the drawing rate.

[0026] Furthermore, when it is determined that the preparation of the target cable does not meet the preset standard according to the niobium-plated layer cracking characteristic value, the corresponding adjustment strategy includes adding a lubricant between the niobium-plated layer and the insulating layer during the drawing process of the stainless steel tube, or reducing the drawing force on the stainless steel tube.

[0027] Furthermore, the niobium-plated layer cracking characteristic value is the average value of the ratio of the crack length of the niobium-plated layer on several cross-sections of the target cable to the inner wall circumference of the stainless steel tube.

[0028] Furthermore, the reduction amplitude of the drawing force is positively correlated with the cracking difference, where the cracking difference is the difference between the niobium-plated layer cracking characteristic value and the preset cracking threshold.

[0029] Compared with the prior art, the beneficial effects of the present invention are that the present invention uses niobium-titanium alloy wire as an inner conductor and polytetrafluoroethylene as an insulating layer; the inner wall of a stainless steel tube is electroplated with niobium of a preset thickness to obtain a target cable, and when it is determined that the niobium electroplating of the outer conductor substrate does not meet the preset standard according to the uniform characteristic value of the niobium plating, the preset density of the current of the next batch is reduced to ensure the uniformity of the niobium plating layer, thereby avoiding local excessive thickness or thinness, which leads to performance degradation; the inner conductor with an insulating layer is inserted into a stainless steel tube that meets the preset standard, the stainless steel tube is drawn to a preset thickness to obtain a target cable, and when it is determined that the preparation of the target cable does not meet the preset standard according to the contact resistance evaluation value, it is secondary determined whether the preparation of the target cable meets the preset standard according to the surface characteristic value of the stainless steel tube, or, the corresponding adjustment strategy is determined according to the cracking characteristic value of the niobium plating layer, so as to improve the reliability and stability of the target cable; the target cable that meets the preset standard is rolled and packaged, thereby improving the preparation efficiency of the target cable.

[0030] Furthermore, the present invention determines whether the niobium plating of the outer conductor substrate meets the preset standard based on the niobium plating uniformity characteristic value. The distribution of the niobium plating layer on the inner wall surface of the stainless steel tube can be accurately measured through the characteristic value, thereby avoiding the performance degradation of the cable caused by the niobium plating layer being too thick or too thin.

[0031] Furthermore, the present invention provides several density adjustment methods for reducing the current density, and each density adjustment method has a different reduction range for the current density, thereby achieving precise adjustment of the reduction range of the current density.

[0032] Furthermore, the present invention determines whether the preparation of the target cable meets the preset standard according to the contact resistance evaluation value, and monitors the preparation process of the target cable in real time, thereby improving the cable quality.

[0033] Furthermore, the present invention provides a contact resistance evaluation value to accurately reflect the heat leakage of the cable in an ultra-low temperature environment, thereby achieving precise control of the cable preparation quality.

[0034] Furthermore, the present invention secondary determines whether the preparation of the target cable meets the preset standard based on the surface characteristic value of the stainless steel tube, thereby improving the accuracy and reliability of the determination, thereby avoiding the waste of resources caused by misjudgment.

[0035] Furthermore, the present invention determines a corresponding adjustment strategy according to the cracking characteristic value of the niobium plating layer, thereby improving the cable preparation efficiency.

[0036] Furthermore, the present invention realizes precise control of the pulling force by positively correlating the reduction amplitude of the pulling force with the cracking difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1Flow chart of a cable preparation method for a quantum computer according to an embodiment of the present invention;

[0038] Figure 2 Flow chart of determining whether the niobium electroplating of the outer conductor substrate meets a preset standard according to an embodiment of the present invention;

[0039] Figure 3 Flow chart of determining whether the preparation of the target cable meets a preset standard according to an embodiment of the present invention;

[0040] Figure 4 Flow chart of determining a corresponding adjustment strategy according to the cracking characteristic value of the niobium plating layer according to an embodiment of the present invention. Detailed implementation manners

[0041] In order to make the objectives and advantages of the present invention clearer and more understandable, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0043] It should be noted that the data in this embodiment are comprehensively analyzed and evaluated from the historical detection data and corresponding historical detection results of the present invention in the three months before this detection. Those skilled in the art can understand that the determination method of the present invention for a single above-mentioned parameter can be to select the value with the highest proportion according to the data distribution as the preset standard parameter, use weighted summation to take the obtained value as the preset standard parameter, substitute each historical data into a specific formula and take the value obtained by using this formula as the preset standard parameter or other selection methods, as long as it satisfies that the method of the present invention can clearly define different specific situations in the single determination process through the obtained values.

[0044] Please refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 4 as shown, which are respectively the flow chart of a cable preparation method for a quantum computer according to an embodiment of the present invention; the flow chart of determining whether the niobium electroplating of the outer conductor substrate meets a preset standard according to an embodiment of the present invention; the flow chart of determining whether the preparation of the target cable meets a preset standard according to an embodiment of the present invention; the flow chart of determining a corresponding adjustment strategy according to the cracking characteristic value of the niobium plating layer according to an embodiment of the present invention.

[0045] The embodiment of the present invention provides a cable preparation method for a quantum computer, including:

[0046] Step S1: Use a niobium-titanium alloy rod as the inner conductor material, and draw the niobium-titanium alloy rod to obtain niobium-titanium alloy wire.

[0047] Step S2: Extrude and coat polytetrafluoroethylene onto the outer surface of the niobium-titanium alloy wire to obtain an inner conductor with an insulating layer.

[0048] Step S3: Coat the outer surface of the stainless steel tube with an insulating material, then place it in a plating solution containing niobium ions, apply a preset current density of 0.07 mA / cm 2 After that, electroplate a niobium coating with a preset thickness of 10 μm on the inner wall of the stainless steel tube. After removing the insulating material, obtain the outer conductor substrate, and measure the thickness of the niobium coating to obtain the niobium plating uniformity characteristic value.

[0049] Step S4: When it is determined that the niobium plating of the outer conductor substrate does not meet the preset standard according to the niobium plating uniformity characteristic value, reduce the current density.

[0050] Step S5: Insert the inner conductor with an insulating layer into the outer conductor substrate that meets the preset standard, and draw the outer conductor substrate to a preset thickness of 0.06 mm to obtain the target cable. Measure the contact resistance value of the target cable to obtain the contact resistance evaluation value.

[0051] Step S6: When it is determined that the preparation of the target cable does not meet the preset standard according to the contact resistance evaluation value, re-determine whether the preparation of the target cable meets the preset standard according to the surface characteristic value of the outer conductor substrate, or determine the corresponding adjustment strategy according to the niobium coating cracking characteristic value.

[0052] Step S7: Wind up and package the target cable that meets the preset standard.

[0053] In this embodiment, the stainless steel tube is made of stainless steel of grade 304.

[0054] In this embodiment, the range of the preset current density is 0.04 mA / cm 2 ~0.08 mA / cm 2 , preferably, the preset current density is 0.07 mA / cm 2 ;

[0055] It can be understood that the current density affects the deposition rate and uniformity of niobium ions during electroplating: too low a current density will lead to too slow a deposition rate and uneven plating; while too high a current density may cause rough plating, bubbles or cracks.

[0056] The selected preset current density of 0.04 mA / cm 2 to 0.08 mA / cm 2 in this embodiment can ensure uniform and dense plating while guaranteeing the deposition rate; at 0.04 mA / cm2 To 0.08 mA / cm 2 Within the range, 0.07 mA / cm is selected 2 , which can not only ensure a high deposition efficiency, but also avoid problems with the quality of the niobium plating layer due to too high current density.

[0057] In this embodiment, the insulating material used to coat the outer surface of the stainless steel tube can be a polymer coating or a ceramic coating, and specific limitations are not made, as long as the requirements for electroplating the inner wall of the stainless steel tube are met.

[0058] Specifically, the process of determining that the niobium electroplating of the outer conductor substrate does not meet the preset standard according to the niobium plating uniformity eigenvalue includes:

[0059] Comparing the niobium plating uniformity eigenvalue with the preset niobium plating uniformity eigenvalue of 0.98;

[0060] If the niobium plating uniformity eigenvalue is greater than or equal to the preset niobium plating uniformity eigenvalue, it is determined that the niobium electroplating of the outer conductor substrate does not meet the preset standard, and the current density is reduced according to the difference between the preset niobium plating uniformity eigenvalue and the niobium plating uniformity eigenvalue;

[0061] Specifically, the value range of the preset niobium plating uniformity eigenvalue is (0.87, 1.12). In this embodiment, the preset niobium plating uniformity eigenvalue is selected as 0.98, but the above values are not limited to this, and those skilled in the art can also adjust the values according to actual needs.

[0062] The niobium plating uniformity eigenvalue is the standard deviation of the thickness of the niobium plating layer, and the thickness of the niobium plating layer is obtained by an ultrasonic thickness gauge.

[0063] Specifically, there are several density adjustment methods for reducing the current density. Among them,

[0064] If the niobium plating uniformity difference is less than the first preset niobium plating uniformity difference of 0.23, the first density adjustment coefficient of 0.98 is used to reduce the current density to the corresponding value;

[0065] If the niobium plating uniformity difference is greater than or equal to the first preset niobium plating uniformity difference and less than the second preset niobium plating uniformity difference of 0.45, the second density adjustment coefficient of 0.96 is used to reduce the current density to the corresponding value;

[0066] If the niobium plating uniformity difference is greater than or equal to the second preset niobium plating uniformity difference, the third density adjustment coefficient of 0.94 is used to reduce the current density to the corresponding value;

[0067] The niobium plating uniformity difference is the difference between the preset niobium plating uniformity eigenvalue and the niobium plating uniformity eigenvalue.

[0068] Specifically, it is determined whether the preparation of the target cable meets the preset standard according to the contact resistance evaluation value, where

[0069] If the contact resistance evaluation value is less than the first preset contact resistance threshold of 1.03, it is determined that the preparation of the target cable meets the preset standard, and the target cable that meets the preset standard is wound and packaged.

[0070] If the contact resistance evaluation value is greater than or equal to the first preset contact resistance threshold and less than the second preset contact resistance threshold of 1.18, it is determined that the preparation of the target cable does not meet the preset standard, and it is determined again whether the preparation of the target cable meets the preset standard according to the surface characteristic value of the stainless steel pipe.

[0071] If the contact resistance evaluation value is greater than or equal to the second preset contact resistance threshold, it is determined that the preparation of the target cable does not meet the preset standard, and the corresponding adjustment strategy is determined according to the niobium plating layer cracking characteristic value.

[0072] Specifically, the process of obtaining the contact resistance evaluation value includes:

[0073] A preset length of the target cable is intercepted and recorded as the first cable.

[0074] Under ultra-low temperature conditions, a contact resistance tester is used to measure the contact resistance value of the first cable in the unbent state, which is recorded as the initial contact resistance value.

[0075] Under ultra-low temperature conditions, a bending test machine is used to bend the first cable to a preset bending radius of 5.4 mm and a contact resistance tester is used to obtain the post-bending contact resistance value of the first cable bent to the preset bending radius.

[0076] The post-bending contact resistance value is compared with the initial contact resistance value to obtain the contact resistance evaluation value.

[0077] Specifically, the range of ultra-low temperature can be below minus 120 degrees Celsius. In this embodiment, the ultra-low temperature condition is at a temperature of -263.15°C.

[0078] Specifically, it is determined again whether the preparation of the target cable meets the preset standard according to the surface characteristic value of the stainless steel pipe, where

[0079] If the surface characteristic value is less than the preset surface characteristic threshold of 1.17, it is determined again that the preparation of the target cable meets the preset standard, and the target cable that meets the preset standard is wound and packaged.

[0080] If the surface feature value is greater than or equal to the preset surface feature threshold, it is determined for the second time that the preparation of the target cable does not meet the preset standard, and the drawing rate of the stainless steel tube is reduced according to the difference between the surface feature value and the preset surface feature threshold;

[0081] The surface feature value is the ratio between the surface roughness of the stainless steel tube and the preset surface roughness of 0.9 μm.

[0082] In this embodiment, the surface roughness of the stainless steel tube is obtained by a surface roughness measuring instrument; the value range of the preset surface roughness is (0.8 μm, 1.6 μm), and preferably, the preset surface roughness is selected as 0.9 μm.

[0083] Specifically, there are several rate adjustment methods for reducing the drawing rate, among which,

[0084] If the surface feature difference is less than the first preset surface feature threshold of 0.13, the drawing rate is reduced to the corresponding value using the first rate adjustment coefficient of 0.97;

[0085] If the surface feature difference is greater than or equal to the first preset surface feature threshold and less than the second preset surface feature threshold of 0.26, the drawing rate is reduced to the corresponding value using the second rate adjustment coefficient of 0.95;

[0086] If the surface feature difference is greater than or equal to the second preset surface feature threshold, the drawing rate is reduced to the corresponding value using the third rate adjustment coefficient of 0.93;

[0087] The surface feature difference is the difference between the surface feature value and the preset surface feature threshold.

[0088] Specifically, according to the niobium plating layer cracking feature value, the adjustment strategy corresponding to the determination that the preparation of the target cable does not meet the preset standard is determined, among which,

[0089] If the niobium plating layer cracking feature value is less than the preset cracking threshold of 0.66, a lubricant is added between the niobium plating layer and the insulating layer during the drawing process of the stainless steel tube;

[0090] If the niobium plating layer cracking feature value is greater than or equal to the preset cracking threshold, the drawing force of the stainless steel tube is reduced according to the difference between the niobium plating layer cracking feature value and the preset cracking threshold.

[0091] Specifically, the niobium plating layer cracking feature value is the average value of the ratio of the crack length of the niobium plating layer on several cross-sections of the target cable to the inner wall circumference of the stainless steel tube.

[0092] Specifically, the reduction amplitude of the drawing force is positively correlated with the cracking difference value. Among them, the positive correlation is, for example, a linear positive correlation or a non-linear positive correlation. The linear slope of the linear positive correlation is not specifically limited. It can be understood that the larger the cracking difference value, the larger the reduction amplitude of the drawing force; the cracking difference value is the difference between the cracking characteristic value of the niobium plating layer and the preset cracking threshold value.

[0093] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0094] The above are only the preferred embodiments of the present invention and are not used to limit the present invention; for those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent substitution, 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 method for preparing a cable for a quantum computer, characterized in that: include: A niobium-titanium alloy rod is used as an inner conductor material, and the niobium-titanium alloy rod is stretched to obtain a niobium-titanium alloy wire; Extruding and coating polytetrafluoroethylene onto the outer surface of the niobium-titanium alloy wire to obtain an inner conductor with an insulating layer; The outer surface of the stainless steel tube is coated with an insulating material and then placed in an electroplating solution containing niobium ions, and a niobium plating layer of a preset thickness is electroplated on the inner wall of the stainless steel tube after a preset current density is applied, and the outer conductor substrate is obtained after the insulating material is removed, and the thickness of the niobium plating layer is measured to obtain a uniform characteristic value of niobium plating; When it is determined according to the niobium plating uniformity characteristic value that the niobium plating of the outer conductor substrate does not meet the preset standard, reducing the current density; Inserting an inner conductor with an insulating layer into an outer conductor substrate that meets a preset standard, drawing the outer conductor substrate to a preset thickness to obtain a target cable, and measuring a contact resistance value of the target cable to obtain a contact resistance evaluation value, wherein the contact resistance evaluation value is a ratio between a contact resistance value after bending and an initial contact resistance value; When the contact resistance evaluation value is greater than or equal to a first preset contact resistance threshold and less than a second preset contact resistance threshold, secondarily determining whether the preparation of the target cable meets the preset standard according to the surface characteristic value of the outer conductor substrate, and, when the contact resistance evaluation value is greater than or equal to the second preset contact resistance threshold, determining a corresponding adjustment strategy according to the cracking characteristic value of the niobium plating layer; The target cables that meet the preset standards are rolled and packaged.

2. The method for preparing a cable for a quantum computer according to claim 1, characterized in that: The process of determining, based on the niobium plating uniformity characteristic value, that the niobium plating of the outer conductor substrate does not meet the preset standard comprises: Compare the niobium plating uniform characteristic value with the preset niobium plating uniform characteristic value; If the niobium plating uniform characteristic value is greater than or equal to the preset niobium plating uniform characteristic value, it is determined that the niobium electroplating of the outer conductor substrate does not meet the preset standard, and the current density is reduced according to the difference between the preset niobium plating uniform characteristic value and the niobium plating uniform characteristic value; The niobium plating uniform characteristic value is the standard deviation of the thickness of the niobium plating layer.

3. The method for preparing a cable for a quantum computer according to claim 2, characterized in that: Several density adjustment methods are provided for reducing the current density, and each density adjustment method has a different reduction range for the current density.

4. The method for preparing a cable for a quantum computer according to claim 3, characterized in that: According to the comparison result that the surface characteristic value of the outer conductor substrate is greater than or equal to the preset surface characteristic threshold, it is determined that the preparation of the target cable does not meet the preset standard, and the drawing rate of the outer conductor substrate is reduced according to the difference between the surface characteristic value and the preset surface characteristic threshold; The surface characteristic value is a ratio between the surface roughness of the outer conductor substrate and a preset surface roughness.

5. The method for preparing a cable for a quantum computer according to claim 4, characterized in that: Several rate adjustment methods are provided for reducing the drawing rate, and each rate adjustment method reduces the drawing rate by a different amount.

6. The method for preparing a cable for a quantum computer according to claim 5, characterized in that: When it is determined according to the cracking characteristic value of the niobium plating layer that the preparation of the target cable does not meet the preset standard, the corresponding adjustment strategy includes adding a lubricant between the niobium plating layer and the insulating layer during the drawing of the stainless steel tube, or reducing the drawing force on the stainless steel tube.

7. The method for preparing a cable for a quantum computer according to claim 6, characterized in that: The crack characteristic value of the niobium plating layer is an average value of the ratio of the crack length of the niobium plating layer on several cross sections of the target cable to the circumference of the inner wall of the stainless steel tube.

8. The method for preparing a cable for a quantum computer according to claim 7, characterized in that: The reduction range of the pulling force is positively correlated with the cracking difference, wherein the cracking difference is the difference between the cracking characteristic value of the niobium plating layer and the preset cracking threshold.

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