A method, procedure, and storage medium for determining the performance of quantum circuits.
By obtaining the low-temperature measured performance results and program simulation of quantum circuits, the characteristic values are determined, solving the problem of low-cost performance evaluation in quantum chip design, realizing efficient performance evaluation, and avoiding high measurement costs.
Patent Information
- Application Number
- CN202311132524.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-04
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2043-09-04
AI Technical Summary
In the process of quantum chip design, how to determine at low cost whether the circuit design scheme will lead to performance problems, especially signal crosstalk, is a challenge, and existing technologies are difficult to accurately evaluate the performance under low-temperature superconductivity at room temperature.
By obtaining the low-temperature measured performance results of a set of quantum circuits, program simulation is performed to determine the characteristic values. Based on the relative magnitude of the simulated values and characteristic values of the newly designed quantum circuit, the performance of the newly designed quantum circuit is judged.
There is no need to test the newly designed quantum circuit in a low-temperature environment, which saves testing costs, improves R&D efficiency, and enables the assessment of quantum circuit performance issues at a low cost.
Smart Images
Figure CN117172324B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of quantum chip technology, and in particular to a method for determining the performance of quantum circuits. Background Technology
[0002] Superconducting quantum chips have various circuit structures, and each part of the circuit structure has a variety of design options. Different design options will lead to different performance of the quantum chip, and some design options will cause problems such as crosstalk in the quantum chip.
[0003] To ensure good performance of quantum chips, various design schemes typically require experimental testing. However, quantum chips need to achieve a superconducting state at extremely low temperatures to enable controlled operations to perform quantum computations and readout operations to obtain the corresponding computation results. The performance of various components in a quantum chip differs between room temperature and the superconducting state. Accurately evaluating performance at low temperatures under room temperature conditions is difficult. Therefore, the experimental testing cost of quantum chips is high.
[0004] Therefore, in the design process, how to determine at low cost whether a quantum circuit design will cause performance problems is a technical problem that needs to be solved. Summary of the Invention
[0005] The purpose of this application is to provide a method for determining the performance of a quantum circuit, so as to determine at low cost whether some parameters in a quantum circuit will cause performance problems.
[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions.
[0007] In a first aspect, embodiments of this application provide a method for determining the performance of a quantum circuit, including:
[0008] The low-temperature measured performance results of each quantum circuit in a set of quantum circuits are obtained; the set of quantum circuits includes multiple quantum circuits with different characteristic parameters.
[0009] Based on the characteristic parameters of each quantum circuit in the set of quantum circuits, a program simulation is performed to obtain the simulation value of each quantum circuit;
[0010] Based on the comparison between the measured low-temperature performance results of each quantum circuit and the simulated values of each quantum circuit, a simulated value is determined from the simulated values of each quantum circuit as a characteristic value.
[0011] The performance of the newly designed quantum circuit is determined based on the relative magnitude of the simulation values to be evaluated and the characteristic values; the simulation values to be evaluated are obtained by program simulation using the characteristic parameters of the newly designed quantum circuit.
[0012] Optionally, each of the quantum circuits includes a first x-line and a first qubit;
[0013] The measured performance results of each quantum circuit at low temperature include: the first x-ray can drive the first quantum bit, or the first x-ray cannot drive the first quantum bit;
[0014] The step of performing program simulation based on the characteristic parameters of each quantum circuit in the set of quantum circuits to obtain the simulation value of each quantum circuit includes: performing program simulation based on the structural parameters of each quantum circuit in the set of quantum circuits to obtain the mutual capacitance value between the first x-line and the first qubit of each quantum circuit;
[0015] The step of determining a simulation value as a characteristic value from the simulation values of each quantum circuit by comparing the measured low-temperature performance results of each quantum circuit with the simulation values of each quantum circuit includes: determining a first mutual capacitance characteristic value by comparing the measured low-temperature performance results of each quantum circuit with the mutual capacitance value of each quantum circuit.
[0016] The step of determining the performance of the newly designed quantum circuit based on the relative magnitude relationship between the simulation value to be evaluated and the characteristic value of the newly designed quantum circuit includes: if the mutual capacitance value between the first x-line and the first qubit of the newly designed quantum circuit is greater than or equal to the first mutual capacitance characteristic value, then it is determined that the first x-line of the newly designed quantum circuit can drive the first qubit.
[0017] Optionally, the steps for obtaining the low-temperature measured performance results of each quantum circuit in a set of quantum circuits include:
[0018] In order of gradually increasing mutual capacitance between the first x-line and the first qubit in the quantum circuit, signals driving the first qubit are applied to the first x-line in the quantum circuit one by one to find the mutual capacitance value at which the first x-line can just drive the first qubit. The structural parameters of the quantum circuit driven by the applied signal and the result of whether the first x-line in the quantum circuit can drive the first qubit are recorded each time.
[0019] Optionally, prior to the step of applying a signal driving the first qubit to the first x-line in the quantum circuit, the quantum circuit performance determination method further includes:
[0020] Under the condition that the first x-line in the quantum circuit can drive the first qubit, different frequency signals are applied to the first x-line of the quantum circuit, the frequency point at which frequency resonance occurs is observed, and then the bit frequency of the first qubit of the quantum circuit is determined by measuring Rabi oscillation.
[0021] Optionally, the quantum circuit includes a first x-line, a first qubit, and a second x-line; the projection of the second x-line onto the plane containing the first qubit intersects with the first qubit.
[0022] The low-temperature measured performance results for each quantum circuit include: the second x-line can drive the first quantum bit, or the second x-line cannot drive the first quantum bit;
[0023] The step of performing program simulation based on the characteristic parameters of each quantum circuit in the set of quantum circuits to obtain the simulation value of each quantum circuit includes: performing program simulation based on the structural parameters of each quantum circuit in the set of quantum circuits to obtain the mutual capacitance value between the second x-line and the first qubit of each quantum circuit;
[0024] The step of determining a simulation value as a characteristic value from the simulation values of each quantum circuit by comparing the measured low-temperature performance results of each quantum circuit with the simulation values of each quantum circuit includes: determining a second mutual capacitance characteristic value by comparing the measured low-temperature performance results of each quantum circuit with the mutual capacitance value of each quantum circuit.
[0025] The step of determining the performance of the newly designed quantum circuit based on the relative magnitude relationship between the simulation value to be evaluated and the characteristic value of the newly designed quantum circuit includes: if the mutual capacitance value between the second x-line and the first qubit of the newly designed quantum circuit is greater than or equal to the characteristic value of the second mutual capacitance value, then the crosstalk between the second x-line and the first qubit of the newly designed quantum circuit is determined.
[0026] Optionally, the steps for obtaining the low-temperature measured performance results of each quantum circuit in a set of quantum circuits include:
[0027] In order of gradually increasing mutual capacitance between the second x-line and the first qubit in the quantum circuit, signals that drive the first qubit are applied to the second x-line in the quantum circuit one by one to find the mutual capacitance value at which the second x-line can just drive the first qubit. The structural parameters of the quantum circuit driven by the applied signal and the result of whether the second x-line in the quantum circuit can drive the first qubit are recorded each time.
[0028] Optionally, the second x-line in the quantum circuit includes an air bridge, and the size of the air bridge in the second x-line of each quantum circuit is different.
[0029] Optionally, the quantum circuit is a link consisting of multiple devices connected together, and each device has its own parameters;
[0030] The low-temperature measured performance results for each quantum circuit include: the signal in the link is distorted, or the signal in the link is not distorted;
[0031] The step of performing program simulation based on the characteristic parameters of each quantum circuit in the set of quantum circuits to obtain the simulation value of each quantum circuit includes: performing program simulation based on the operating parameters of each quantum circuit to obtain the parameters of each device in each quantum circuit;
[0032] The step of determining a simulation value as an eigenvalue from the simulation values of each quantum circuit by comparing the measured low-temperature performance results of each quantum circuit with the simulation values of each quantum circuit includes: determining the maximum and minimum eigenvalues of each device by comparing the measured low-temperature performance results of each quantum circuit with the parameters of each device in each quantum circuit.
[0033] The step of determining the performance of the newly designed quantum circuit based on the relative magnitude relationship between the simulation value to be evaluated and the eigenvalue includes: if the parameter of each device in the newly designed quantum circuit is located between the minimum eigenvalue and the maximum eigenvalue, then the x-signal of the quantum circuit is determined to be distortion-free.
[0034] Secondly, embodiments of this application provide a computer-readable storage medium storing a computer program or instructions, which, when executed by a computer, implements the quantum circuit performance determination method of the first aspect.
[0035] Thirdly, embodiments of this application provide a computer program including instructions that, when executed by a computer, implement the quantum circuit performance determination method of the first aspect.
[0036] Compared with the prior art, this application has the following advantages:
[0037] The quantum circuit performance determination method provided in this application allows for the determination of the performance of a newly designed quantum circuit simply by comparing the relative magnitudes of a specific parameter of the quantum circuit with a pre-obtained characteristic value. This eliminates the need to place the newly designed quantum circuit in a low-temperature environment for actual testing, saving the cost of actual testing and improving R&D efficiency. Attached Figure Description
[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0039] Figure 1This is a schematic diagram of a method for determining the performance of a quantum circuit according to an embodiment of this application;
[0040] Figure 2 A schematic diagram of a quantum circuit having a first x-line and a first qubit is provided for an embodiment of this application;
[0041] Figure 3 A schematic diagram of a quantum circuit provided for an embodiment of this application, in which a first quantum bit may crosstalk with other control lines;
[0042] Figure 4 A schematic diagram of a quantum circuit that modifies the structure of the second x-ray to prevent crosstalk, provided as an embodiment of this application;
[0043] Figure 5 A schematic diagram of a link from a room-temperature signal source to a quantum bit is provided for an embodiment of this application;
[0044] Figure 6 A schematic diagram of a quantum chip and packaging box provided for an embodiment of this application;
[0045] Figure 7 A schematic diagram illustrating four bonding methods for the first layer bonding sheet of a quantum chip, provided for embodiments of this application;
[0046] Figure 8 This is a schematic diagram of four bonding methods for a second-layer bonding sheet of a quantum chip provided in an embodiment of this application. Detailed Implementation
[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described in the accompanying drawings can generally be arranged and designed in various different configurations.
[0048] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0049] In the description of this application, it should be noted that relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.
[0050] To reduce the experimental procedures of cryogenic experiments and to determine at a low cost whether certain parameters in a quantum circuit will cause performance problems, embodiments of this application provide a method for determining the performance of a quantum circuit, such as... Figure 1 ,include:
[0051] Step A. Obtain the low-temperature measured performance results of each quantum circuit in a set of quantum circuits; this set of quantum circuits includes multiple quantum circuits with different characteristic parameters;
[0052] Step B. Perform program simulation based on the characteristic parameters of each quantum circuit in this set of quantum circuits to obtain the simulation value of each quantum circuit;
[0053] Step C. Based on the comparison between the measured low-temperature performance results of each quantum circuit and the simulated value of each quantum circuit, determine a simulated value as the characteristic value from the simulated value of each quantum circuit;
[0054] Step D. Determine the performance of the newly designed quantum circuit based on the relative magnitudes of the simulation values to be evaluated and the characteristic values of the newly designed quantum circuit; the simulation values to be evaluated are obtained by program simulation using the characteristic parameters of the newly designed quantum circuit.
[0055] Based on the quantum circuit performance determination method described herein, the characteristic values of the quantum circuit are obtained. When designing a new quantum circuit, the performance of the newly designed quantum circuit can be determined simply by comparing the relative magnitudes of its characteristic parameters and characteristic values (the determined performance can refer to whether it is qualified or unqualified, or quantify the degree of superiority or inferiority). It eliminates the need to place the newly designed quantum circuit in a low-temperature environment for experimental testing, saving experimental costs and improving R&D efficiency. This is the beneficial effect of the embodiments of this application.
[0056] It should be noted that the description of the steps in this application does not impose a fixed order. The order of the steps can be flexibly set as long as there is no contradiction. For example, regarding steps A and B above, step A can be executed first, followed by step B, or vice versa. Executing step A first, followed by step B, can yield more definitive experimental results. For instance, if the experimental results include both qualified and unqualified quantum circuits, executing step B first, followed by step A, might lead to the following situation: step A, which follows step B, discovers that the measured performance of all quantum circuits in step B is unqualified. In this case, it is necessary to re-simulate based on the qualified quantum circuits from step A and return to step B.
[0057] The following example, using the design of a specific qubit and its xy-line, illustrates one implementation of the aforementioned method for determining quantum circuit performance. Specifically, the quantum circuit may include, for example, control lines (including xy-line and z-line) for operating on qubits implemented based on Josephson junctions. It may also include readout structures for reading the qubit, such as a readout bus and a readout resonant cavity.
[0058] In this application, the aforementioned xy line is referred to as the x-line. In a successful design, the x-line can drive the corresponding qubit; in a failed design, the x-line cannot drive the corresponding qubit. That is, the experimental performance at low temperatures may indicate whether the qubit can be driven or not.
[0059] When designing an X-ray, the capacitance value between the X-ray and the qubit that the X-ray needs to drive can be referenced, and this capacitance value can be used as the simulation value for the quantum circuit.
[0060] The mutual capacitance value can be changed through structural parameters, such as the thickness of the x-line, its relative position to the qubit, and the relative distance. These structural parameters can be used as characteristic parameters. This can be achieved by controlling variables, for example, fixing the thickness of the x-line and the position of the qubit, with the x-line perpendicular to the qubit. The only variable is the translation of the x-line along its direction, resulting in different positions. The amount of translation from the initial position is considered a structural parameter. There can be one or more characteristic parameters.
[0061] like Figure 2 The quantum circuit includes a first x-line 101 and a first qubit 102. The following describes one implementation of the quantum circuit performance determination method corresponding to this quantum circuit.
[0062] The low-temperature measured performance results of each quantum circuit include: whether the first x-line can drive the first qubit, or whether the first x-line cannot drive the first qubit; the signal driving the first qubit can be applied to the first x-line of the quantum circuit one by one in the order of gradually increasing mutual capacitance between the first x-line and the first qubit in the quantum circuit, so as to find the mutual capacitance value at which the first x-line can just drive the first qubit, and record the structural parameters of the quantum circuit driven by the applied signal each time and whether the first x-line in the quantum circuit can drive the first qubit therein.
[0063] For each quantum circuit, the bit frequency of the first qubit can be determined first. The signal applied to the first x-ray is limited to a frequency equal to the bit frequency. Alternatively, the first qubits of each quantum circuit can have the same bit frequency; in this case, only the bit frequency of the first qubit of one of the quantum circuits needs to be measured.
[0064] The method for measuring the bit frequency is as follows: Under the condition that the first x-line in the quantum circuit can drive the first qubit (for example, when the distance between the first x-line and the first qubit is close enough so that the mutual capacitance value between them is large enough, the condition that the first x-line can drive the first qubit is satisfied), different frequency signals are applied to the first x-line of the quantum circuit, the frequency point at which frequency resonance occurs is observed, and then the bit frequency is determined by measuring the Rabi oscillation.
[0065] After obtaining the bit frequency, low-temperature actual measurements are performed on the quantum circuit. For example, a total of 6 quantum circuits are actually measured at low temperature, namely quantum circuit 1, quantum circuit 2, quantum circuit 3, quantum circuit 4, quantum circuit 5, and quantum circuit 6. Among them, the mutual capacitance values of quantum circuits 1 to 6 increase in sequence. For example, in quantum circuit 1, the first x-line is the farthest from the first qubit, and in quantum circuit 6, the first x-line is the closest to the first qubit. The actual measurement results show that quantum circuits 1 to 3 cannot be driven, and quantum circuits 4 to 6 can be driven.
[0066] Corresponding to the quantum circuit in the above actual measurement process, step B includes: performing program simulation based on the structural parameters of each quantum circuit in this group to obtain the mutual capacitance value between the first x-line and the first qubit of each quantum circuit; for example, the mutual capacitance value a1 is obtained in quantum circuit 1, the mutual capacitance value a2 is obtained in quantum circuit 2, the mutual capacitance value a3 is obtained in quantum circuit 3, the mutual capacitance value a4 is obtained in quantum circuit 4, the mutual capacitance value a5 is obtained in quantum circuit 5, and the mutual capacitance value a6 is obtained in quantum circuit 6; a1 < a2 < a3 < a4 < a5 < a6. The unit can be taken as attofarad aF, and 1 aF = 10^-18 F.
[0067] After the actual measurement and simulation are completed, step C includes: determining a mutual capacitance value as the first mutual capacitance eigenvalue from the mutual capacitance values of each quantum circuit according to the comparison between the low-temperature actual measurement performance results of each quantum circuit and the mutual capacitance value of each quantum circuit; in the above example, the comparison between the low-temperature actual measurement performance results of each quantum circuit and the mutual capacitance value of each quantum circuit is as shown in the following table:
[0068]
[0069] Among a1 to a6, a4 that can just be driven can be selected as the first mutual capacitance eigenvalue.
[0070] After obtaining the first mutual capacitance characteristic value, when designing a new quantum circuit, the mutual capacitance value between the qubit and the x-line driving it can be obtained by simulating the newly designed quantum circuit. Then, the mutual capacitance value is compared with the first mutual capacitance characteristic value to determine whether the x-line can drive the qubit. Step D includes: if the mutual capacitance value between the first x-line and the first qubit of the newly designed quantum circuit is greater than or equal to the first mutual capacitance characteristic value, then it is determined that the first x-line of the newly designed quantum circuit can drive the first qubit.
[0071] For the first qubit, in addition to the aforementioned question of whether it can be driven by the first x-ray, there may also be the problem of crosstalk from other control lines, such as... Figure 3 The second x-line 103 is above or below the first qubit 102. The projection of the second x-line on the plane where the first qubit is located intersects with the first qubit. The second x-line may be used to drive other qubits, but it may have a driving effect on the first qubit and cause crosstalk.
[0072] To address the crosstalk problem, the low-temperature measured performance results for each quantum circuit in this quantum circuit performance determination method include: the second x-line can drive the first qubit, or the second x-line cannot drive the first qubit. The ability to drive constitutes crosstalk; therefore, the low-temperature measured performance results can also be either crosstalk-related or non-crosstalk-related.
[0073] The signal driving the first qubit can be applied to the second x-line of the quantum circuit one by one in order of gradually increasing mutual capacitance between the second x-line and the first qubit, so as to find the mutual capacitance value at which the second x-line can just drive the first qubit, and record the structural parameters of the quantum circuit driven by the applied signal each time and whether the second x-line in the quantum circuit can drive the first qubit therein.
[0074] Low-temperature experiments were conducted on quantum circuits, including six circuits: quantum circuit 11, quantum circuit 12, quantum circuit 13, quantum circuit 14, quantum circuit 15, and quantum circuit 16. The mutual capacitance values of quantum circuits 11 through 16 increase sequentially. This increase in mutual capacitance can be attributed to the size of the air bridge. For example, quantum circuit 11 has the largest air bridge in its second x-line, therefore the minimum distance between the second x-line and the first qubit in quantum circuit 11 is the farthest among all quantum circuits. Conversely, quantum circuit 16 has the smallest air bridge in its second x-line, therefore the minimum distance between the second x-line and the first qubit in quantum circuit 16 is the shortest among all quantum circuits. The experimental results showed that quantum circuits 11 through 13 could not be driven, while quantum circuits 14 through 16 could be driven.
[0075] In setting mutual capacitance values using air bridge dimensions, a larger air bridge results in a smaller mutual capacitance value and less crosstalk. However, a larger air bridge also increases manufacturing complexity. Therefore, it's necessary to find a minimum air bridge size, which corresponds to the maximum mutual capacitance value. Air bridge size can refer to the length of the air bridge (with a fixed height) or the height of the air bridge (with a fixed length). Using structures like air strips or indium pillars to replace the aforementioned air bridges to change the mutual capacitance value works similarly. It can also change the size of X-rays on a plane, such as... Figure 4 Set a bend with length a and width b, and change the mutual capacitance value by changing the size of a or b.
[0076] Corresponding to the quantum circuits in the above-described experimental process, step B includes: performing program simulation based on the structural parameters of each quantum circuit in this group of quantum circuits to obtain the mutual capacitance value between the second x-line and the first qubit of each quantum circuit; for example, mutual capacitance value a11 is obtained in quantum circuit 11, mutual capacitance value a12 is obtained in quantum circuit 12, mutual capacitance value a13 is obtained in quantum circuit 13, mutual capacitance value a14 is obtained in quantum circuit 14, mutual capacitance value a15 is obtained in quantum circuit 15, and mutual capacitance value a16 is obtained in quantum circuit 16; a11 <a12<a13<a14<a15<a16。
[0077] After completing the actual measurements and simulations, step C includes: based on the comparison between the low-temperature measured performance results of each quantum circuit and the mutual capacitance value of each quantum circuit, determining a mutual capacitance value from the mutual capacitance values of each quantum circuit as the second mutual capacitance value characteristic value; in the above example, the comparison between the low-temperature measured performance results of each quantum circuit and the mutual capacitance value of each quantum circuit is shown in the table below:
[0078]
[0079] From a11 to a16, a13, which is just not driven, can be selected as the second mutual capacitance characteristic value.
[0080] After obtaining the second mutual capacitance value characteristic, when designing a new quantum circuit, the mutual capacitance value between the other control lines and the first qubit can be obtained by simulating the newly designed quantum circuit. Then, the mutual capacitance value is compared with the second mutual capacitance value characteristic to determine whether these control lines can cause crosstalk to the qubit. Step D includes: if the mutual capacitance value between the second x line of the newly designed quantum circuit and the first qubit is greater than or equal to the second mutual capacitance value characteristic, then the crosstalk between the second x line of the newly designed quantum circuit and the first qubit is determined.
[0081] The above are implementation methods for the performance between specific qubits and control lines, all examples of X-ray-related performance at low temperatures. Furthermore, the signals used in the control and readout operations of superconducting quantum chips need to be transmitted from the source at room temperature to the cryogenic layer in the superconducting state. This link involves multiple devices and their interconnections, which may also present problems. For example, in the entire signal link from X-ray transmission to the qubit, there are many devices and significant insertion loss, making accurate evaluation of the entire link difficult. This quantum circuit performance determination method can also be used to assess whether signal distortion occurs in the link, avoiding the need for cryogenic superconducting testing of the link for each evaluation.
[0082] In the method for determining the performance of a quantum circuit link, the quantum circuit is a link composed of multiple devices connected together. Each device has its own parameters, and the steps can be set as follows:
[0083] In step A, the low-temperature measured performance results of each quantum circuit include: the signal in the link is distorted, or the signal in the link is not distorted;
[0084] Step B includes: performing program simulation based on the operating parameters of each quantum circuit in Step A to obtain the parameters of each device in each quantum circuit;
[0085] Step C includes: comparing the low-temperature measured performance results of each quantum circuit with the parameters of each device in each quantum circuit. Specifically, first look at the parameters of a device, and from the quantum circuits whose low-temperature measured performance results show that the signal in the link does not distort, find a quantum circuit with the maximum value of the device parameter and a quantum circuit with the minimum value of the device parameter, and use these two circuits to determine the maximum and minimum eigenvalues of the device parameter; the parameters of other devices are determined in the same way.
[0086] Step D includes: if the parameter of a device in the newly designed quantum circuit is not between the minimum eigenvalue and the maximum eigenvalue, then it is determined that the device in the quantum circuit has a problem.
[0087] The newly designed quantum circuit can be used to identify which device(s) have preset parameters exceeding the range defined by the minimum and maximum eigenvalues through this quantum circuit performance determination method. By pinpointing the problematic devices and making targeted corrections, the x-signal of the quantum circuit can be prevented from being distorted. Furthermore, the distortion can be observed at each node through simulation using ADS software or other circuit simulation software.
[0088] Figure 5An example of a link is given, in which a signal source 21 is composed of a finite pulse width cosine signal device 211, a periodic cosine signal device 212 and a mixer 213, and then passes through an attenuator 221, a filter 222, a DC module 223, a connector 224, a PCB 225, a bonding wire 226 and a coupling capacitor module 23 in sequence, and is connected to a quantum bit qubit.
[0089] The parameters of attenuator 221, filter 222, and DC module 223 include, for example, resistance, capacitance, inductance, and S-parameters. The maximum and minimum critical values can be obtained through step C of this quantum circuit performance determination method. These maximum and minimum critical values are used as the maximum and minimum eigenvalues, respectively, limiting the approximate usable range for each device. This allows for the creation of a link that meets the usage requirements.
[0090] Regarding the bonding line 226, different bonding methods can be designed. Whether a bonding method will cause crosstalk can also be determined by the quantum circuit performance determination method described in this paper.
[0091] Figure 6 An example of a quantum chip 31 and a package 32 requiring bonding is shown. The quantum chip has two layers (one layer in height), each with a perimeter of pad bonding pads forming a square. These bonding pads are the small squares shown in the diagram. The inner perimeter, represented by 311, is called the first layer, and the outer perimeter, represented by 312, is called the second layer. The package 32 also has two layers, each with a perimeter of pad bonding pads forming a square. The inner perimeter, represented by 321, is called the first layer, and the outer perimeter, represented by 322, is called the second layer. Due to the large number of bonding pads on the quantum chip and the package, the bonding pads on the quantum chip and the package are misaligned.
[0092] To test the performance of different bonding methods, you can follow... Figure 7 The method was used to test four bonding methods for the first layer of the quantum chip (four bonding methods for each of the four sides of the square). Figure 8 The method was used to test four bonding methods for the second layer of the quantum chip bonding sheet.
[0093] In this method for determining the performance of quantum circuits, step A includes: ... Figure 7 , Figure 8 Low-temperature tests were conducted on the structure, and the low-temperature performance results for eight bonding methods were obtained, with the results showing either crosstalk or no crosstalk. In the low-temperature performance results, regardless of... Figure 7 still Figure 8 The bonding method on the top and right sides is non-crosstalk.
[0094] Next, step B includes: […]. Figure 7 , Figure 8 The structure is simulated using a program to obtain the crosstalk of various bonds, and the crosstalk is used as the simulation value. For example... Figure 7 In the diagram, the crosstalk of the lower bonding method is -20dB, the crosstalk of the left bonding method is -15dB, the crosstalk of the upper bonding method is -35dB, and the crosstalk of the right bonding method is -30dB. Therefore, the maximum crosstalk among the non-crosstalk methods can be used as the feature value. That is, in step C, -30dB is selected as the feature value.
[0095] In step D, the newly designed quantum circuit is simulated. If the crosstalk is greater than 30dB, the performance of the newly designed quantum circuit is deemed unqualified. If the crosstalk is less than or equal to 30dB, the newly designed quantum circuit is deemed to be free of crosstalk.
[0096] Based on the above embodiments, this application provides a computer-readable storage medium storing a computer program or instructions. When the computer program or instructions are executed by a computer, the above-described method for determining the performance of quantum circuits is implemented. This application also provides a computer program including instructions, which, when executed by a computer, causes the computer to perform the above-described method for determining the performance of quantum circuits.
[0097] The apparatus and system embodiments described above are merely illustrative. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement these embodiments without any creative effort.
[0098] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method of quantum circuit performance determination, the method comprising: The method comprises the following steps: obtaining low-temperature measured performance results of each quantum circuit in a group of quantum circuits; the group of quantum circuits comprises a plurality of quantum circuits with different characteristic parameters; the low-temperature measured performance result of each quantum circuit is capable of driving or incapable of driving; the characteristic parameters comprise structural parameters; performing program simulation according to the characteristic parameters of each quantum circuit in the group of quantum circuits to obtain a simulation value of each quantum circuit; the simulation value comprises a mutual capacity value, a crosstalk value or a parameter value of a device in the circuit; determining a simulation value as a characteristic value from the simulation values of the plurality of quantum circuits according to the low-temperature measured performance result of each quantum circuit and the simulation value of each quantum circuit; the characteristic value comprises a simulation value of a quantum circuit that can just be driven in the plurality of quantum circuits; determining the performance of a newly designed quantum circuit according to the relative size relationship between the to-be-evaluated simulation value of the newly designed quantum circuit and the characteristic value; the to-be-evaluated simulation value is obtained by performing program simulation on the characteristic parameters of the newly designed quantum circuit.
2. The quantum circuit performance determination method of claim 1, wherein, each quantum circuit comprises a first x-line and a first quantum bit; the low-temperature measured performance result of each quantum circuit comprises that the first x-line can drive the first quantum bit or the first x-line cannot drive the first quantum bit; the step of performing program simulation according to the characteristic parameters of each quantum circuit in the group of quantum circuits to obtain a simulation value of each quantum circuit comprises: performing program simulation according to the structural parameters of each quantum circuit in the group of quantum circuits to obtain a mutual capacity value between the first x-line and the first quantum bit of each quantum circuit; the step of determining a simulation value as a characteristic value from the simulation values of each quantum circuit according to the low-temperature measured performance result of each quantum circuit and the simulation value of each quantum circuit comprises: determining a mutual capacity value as a first mutual capacity value characteristic value from the mutual capacity values of each quantum circuit according to the comparison between the low-temperature measured performance result of each quantum circuit and the mutual capacity value of each quantum circuit; the step of determining the performance of a newly designed quantum circuit according to the relative size relationship between the to-be-evaluated simulation value of the newly designed quantum circuit and the characteristic value comprises: if the mutual capacity value between the first x-line and the first quantum bit of the newly designed quantum circuit is greater than or equal to the first mutual capacity value characteristic value, it is determined that the first x-line of the newly designed quantum circuit can drive the first quantum bit.
3. The quantum circuit performance determination method of claim 2, wherein, The step of obtaining low-temperature measured performance results of each quantum circuit in a group of quantum circuits comprises: in order of gradually increasing mutual capacity values between the first x-line and the first quantum bit in the quantum circuit, the signal for driving the first quantum bit is applied to the first x-line in the quantum circuit one by one to find the mutual capacity value at which the first x-line can just drive the first quantum bit, and the structural parameters of the quantum circuit in which the signal is applied to drive each time and the result of whether the first x-line in the quantum circuit can drive the first quantum bit therein are recorded.
4. The quantum circuit performance determination method of claim 3, wherein, Before the step of applying the signal for driving the first quantum bit to the first x-line in the quantum circuit, the method further comprises: In the condition that the first x-line in the quantum circuit can drive the first quantum bit, a different frequency signal is added to the first x-line of the quantum circuit, and a frequency point at which frequency resonance occurs is observed, and then a bit frequency of the first quantum bit of the quantum circuit is determined by measuring Rabi oscillation.
5. The quantum circuit performance determination method of claim 1, wherein, The quantum circuit comprises a first x-line, a first quantum bit, and a second x-line. A projection of the second x-line on a plane in which the first quantum bit is located intersects the first quantum bit. The low-temperature measured performance result of each quantum circuit comprises that the second x-line can drive the first quantum bit or the second x-line cannot drive the first quantum bit. The step of performing program simulation according to the characteristic parameters of each quantum circuit in the group of quantum circuits to obtain a simulation value of each quantum circuit comprises: performing program simulation according to structure parameters of each quantum circuit in the group of quantum circuits to obtain a mutual capacity value between the second x-line and the first quantum bit of each quantum circuit. The step of determining a simulation value as a characteristic value from the simulation value of each quantum circuit according to a comparison between the low-temperature measured performance result of each quantum circuit and the simulation value of each quantum circuit comprises: determining a second mutual capacity value characteristic value according to a comparison between the low-temperature measured performance result of each quantum circuit and the mutual capacity value of each quantum circuit. The step of determining the performance of the newly designed quantum circuit according to a relative size relationship between the to-be-evaluated simulation value of the newly designed quantum circuit and the characteristic value comprises: if the mutual capacity value between the second x-line and the first quantum bit of the newly designed quantum circuit is greater than or equal to the second mutual capacity value characteristic value, determining that the second x-line and the first quantum bit of the newly designed quantum circuit have crosstalk.
6. The quantum circuit performance determination method of claim 5, wherein, The step of obtaining a low-temperature measured performance result of each quantum circuit in a group of quantum circuits comprises: In an order of gradually increasing mutual capacity values between the second x-line and the first quantum bit in the quantum circuit, a signal for driving the first quantum bit is applied to the second x-line in the quantum circuit one by one to find a mutual capacity value at which the second x-line can just drive the first quantum bit, and structure parameters of a quantum circuit to which the signal is applied each time and a result of whether the second x-line in the quantum circuit can drive the first quantum bit in the quantum circuit are recorded.
7. The quantum circuit performance determination method of claim 6, wherein, The second x-line in the quantum circuit comprises an air bridge, and sizes of the air bridges of the second x-line of each quantum circuit are different.
8. The quantum circuit performance determination method of claim 1, wherein, The quantum circuit is a link connected by a plurality of devices, and each device has a parameter of the device. The low-temperature measured performance result of each quantum circuit comprises that a signal in the link is distorted or the signal in the link is not distorted. The step of performing program simulation according to the characteristic parameters of each quantum circuit in the group of quantum circuits to obtain a simulation value of each quantum circuit comprises: performing program simulation according to working parameters of each quantum circuit to obtain the parameter of each device of each quantum circuit. The step of determining a simulation value as a characteristic value from the simulation values of each quantum circuit according to the comparison between the low-temperature measured performance results of each quantum circuit and the simulation values of each quantum circuit includes: determining a maximum characteristic value and a minimum characteristic value of the parameters of each device according to the comparison between the low-temperature measured performance results of each quantum circuit and the parameters of each device of each quantum circuit; The step of determining the performance of the newly designed quantum circuit according to the relative size relationship between the to-be-evaluated simulation value of the newly designed quantum circuit and the characteristic value includes: if the parameter of a device of the newly designed quantum circuit is not located between the minimum characteristic value and the maximum characteristic value, determining that there is a problem with the device of the quantum circuit.
9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program or instructions, and when the computer program or instructions are executed by a computer, the quantum circuit performance determination method in any one of claims 1-8 is implemented.
10. A computer program, characterized in that, The computer program includes instructions, and when the computer program is executed by a computer, the quantum circuit performance determination method in any one of claims 1-8 is implemented.
Citation Information
Patent Citations
Simulation method and device, equipment and storage medium
CN115329975A
Capacitor design method and device, electronic equipment, medium and program product
CN116401993A