Method for determining parameters of crosstalk microwave signal of quantum bit driving line and storage medium

Abstract

The invention discloses a method for determining a parameter of a crosstalk microwave signal of a quantum bit driving line and a storage medium, belongs to the technical field of quantum computing, and is used for determining the parameter of the crosstalk microwave signal transmitted on the quantum bit driving line. The method comprises the following steps: acquiring a voltage matrix and a phase matrix of an initial microwave signal applied to a driving line of each quantum bit; carrying out product processing on a preset amplitude crosstalk coefficient and the voltage matrix to obtain an amplitude crosstalk matrix, and carrying out addition processing on a preset phase crosstalk coefficient and the phase matrix to obtain a phase crosstalk matrix; performing cosine processing on the phase crosstalk matrix to obtain a cosine phase function, and performing product processing on the cosine phase function and the amplitude crosstalk matrix to obtain a target crosstalk matrix; and performing square root processing on the target crosstalk matrix to obtain parameters of crosstalk microwave signals transmitted on the driving line. According to the invention, the parameters of the crosstalk microwave signal transmitted on the drive line of the quantum bit can be determined without an experiment, and compensation and calibration are facilitated.

Description

Technical Field

[0001] This application relates to the field of quantum computing technology, and in particular to a method for determining the parameters of crosstalk microwave signals of qubit driving lines and a storage medium thereon. Background Technology

[0002] A quantum computer is a physical device that performs high-speed mathematical and logical operations, stores and processes quantum information, following the laws of quantum mechanics. The main characteristics of quantum computers include high operating speed, strong information processing capabilities, and a wide range of applications. Compared to conventional computers, the greater the amount of information processed, the more advantageous it is for quantum computers to perform calculations, and the more accurately the calculations can be ensured.

[0003] Superconducting quantum processors composed of microwave-controlled qubit arrays represent the forefront of contemporary digital quantum computing, analog quantum simulation, and modeling. Microwave-controlled qubits enable controllable, high-fidelity single-qubit gates. A key requirement for quantum computing is precise microwave control applied to the drive lines of the qubits, allowing individual control over each qubit. However, microwave crosstalk is a major factor hindering the development of scalable quantum computing. Microwave crosstalk is defined as follows: although the microwave signal applied to a specific drive line is designed to control only one qubit, crosstalk propagation of that signal to other qubits occurs.

[0004] When microwave signals are applied to the frequency drive lines of other qubits, they directly affect the frequency of the current qubit, causing its operating frequency to shift and thus reducing the accuracy of its quantum gate operation. Therefore, it is necessary to calibrate the microwave signals on the frequency drive lines of qubits after they are affected by crosstalk in order to perform calibration and compensation.

[0005] It should be noted that the information disclosed in the background section of this application is intended only to enhance the understanding of the general background of this application, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this application is to provide a method and storage medium for determining the parameters of crosstalk microwave signals on a qubit driving line, which solves the problem that microwave crosstalk between qubits is easily obtained in the prior art, and the parameters of the actual microwave signal transmitted on the qubit driving line can be determined without experimentation, which facilitates compensation and calibration.

[0007] To address the above technical problems, the first aspect of this application proposes a method for determining the parameters of crosstalk microwave signals of qubit driving lines, the method comprising:

[0008] Obtain the voltage matrix and phase matrix of the initial microwave signal applied to the driving line of each qubit; wherein the number of rows and columns of the voltage matrix and the phase matrix are the same as the number of qubits, and each column of the voltage matrix represents the voltage of a qubit, and each column of the phase matrix represents the phase of a qubit;

[0009] The amplitude crosstalk matrix is ​​obtained by multiplying the voltage matrix with the preset amplitude crosstalk coefficient, and the phase crosstalk matrix is ​​obtained by adding the phase matrix with the preset phase crosstalk coefficient.

[0010] The phase crosstalk matrix is ​​cosine processed to obtain a cosine phase function, and the cosine phase function is multiplied with the amplitude crosstalk matrix to obtain the target crosstalk matrix.

[0011] The signal parameters of the crosstalk microwave signal are obtained by taking the square root of the target crosstalk matrix.

[0012] Optionally, as described above, obtaining the voltage matrix and phase matrix of the initial microwave signal applied to the driving line of each qubit includes:

[0013] Obtain a voltage vector representing the voltage and amplitude of the initial microwave signal applied to the drive line of each qubit;

[0014] The voltage matrix is ​​obtained by horizontally shifting the vector values ​​in the voltage vector.

[0015] The phase values ​​of the initial microwave signal applied to the driving line of each quantum bit are obtained, and a phase matrix is ​​formed.

[0016] Optionally, before multiplying the cosine phase function with the amplitude crosstalk matrix to obtain the target crosstalk matrix, the method further includes:

[0017] Extract one row of the amplitude crosstalk coefficients used to characterize the target qubit from the amplitude crosstalk matrix as the first amplitude crosstalk matrix;

[0018] The first amplitude crosstalk matrix is ​​transposed to obtain the second amplitude crosstalk matrix;

[0019] The product of the first amplitude crosstalk matrix and the second amplitude crosstalk matrix is ​​obtained as the amplitude crosstalk matrix of the target qubit.

[0020] Optionally, before performing cosine processing on the phase crosstalk matrix to obtain the cosine phase function, the method described above further includes:

[0021] Extract one row from the phase crosstalk matrix that represents the phase crosstalk coefficient of the target qubit as the first phase crosstalk matrix;

[0022] The second phase crosstalk matrix is ​​obtained by translating the first phase crosstalk matrix along the longitudinal direction.

[0023] The first phase crosstalk matrix is ​​transposed and then translated laterally to obtain the third phase crosstalk matrix.

[0024] The phase crosstalk matrix of the target qubit is obtained by subtracting the second phase crosstalk matrix from the third phase crosstalk matrix.

[0025] Optionally, the method described above involves multiplying the cosine phase function with the amplitude crosstalk matrix to obtain the target crosstalk matrix, including:

[0026] The target crosstalk matrix of the target qubit is obtained by multiplying the cosine phase function with the amplitude crosstalk matrix of the target qubit.

[0027] The microwave signal parameters are obtained by square root processing of the target crosstalk matrix, including:

[0028] The microwave signal parameters transmitted on the driving line of the target qubit are obtained by square rooting the target crosstalk matrix of the target qubit.

[0029] The second aspect of this application proposes a method for determining the operating frequency of a qubit, comprising:

[0030] Obtain the capacitance parameters of each qubit on the quantum processor, wherein the capacitance parameters include the qubit's own capacitance parameters and the coupling capacitance parameters between the qubit and the driving line;

[0031] The signal parameters of the crosstalk microwave signal are obtained according to the method described in any of the first aspects above;

[0032] The operating frequency of the quantum bit is determined based on the capacitance parameters and the signal parameters.

[0033] Optionally, the operating frequency can be determined as follows using the method described above:

[0034]

[0035] Among them, the For the operating frequency, the Ω Qj For the capacitance parameter, C Qj The signal parameters are as described above.

[0036] Optionally, the capacitance parameters are as follows:

[0037]

[0038] in, These are coupling capacitor parameters. C j It is the capacitance parameter of the qubit itself. Let be Planck's constant. It is the characteristic magnitude of the charge zero-point fluctuation of a qubit.

[0039] A third aspect of this application proposes a method for determining the qubit crosstalk coefficient, comprising:

[0040] Obtain the amplitude crosstalk coefficient and phase crosstalk coefficient of the preset qubit;

[0041] The operating frequency of the qubit is determined by the method described in any of the second aspects above, based on the amplitude crosstalk coefficient and the phase crosstalk coefficient.

[0042] The Rabi oscillation experiment was performed on the qubit to obtain the measurement frequency of the qubit;

[0043] The amplitude crosstalk coefficient and phase crosstalk coefficient when the operating frequency is the same as the measurement frequency are determined as the target crosstalk coefficient.

[0044] The fourth aspect of this application proposes a readable storage medium having a computer program stored thereon. When executed by a processor, the computer program can determine the signal parameters of the crosstalk microwave signal transmitted on the drive line using the method for determining microwave crosstalk on the qubit drive line as described in any of the first aspects above, or determine the operating frequency of the qubit using the method for determining the operating frequency of the qubit as described in any of the second aspects above, or determine the crosstalk coefficient using the method for determining the crosstalk coefficient of the qubit as described in the third aspect above.

[0045] Compared with the prior art, this application has the following beneficial effects:

[0046] This application first determines the voltage matrix and phase matrix of the initial microwave signal applied to each qubit as the initial matrix without crosstalk influence. Then, it processes the voltage matrix and phase matrix according to preset amplitude crosstalk coefficients and phase crosstalk coefficients to obtain the amplitude crosstalk matrix and phase crosstalk matrix after crosstalk influence. Next, it obtains the target crosstalk matrix by cosine processing of the phase crosstalk matrix and multiplying the processed cosine phase function with the amplitude crosstalk matrix. This target crosstalk matrix is ​​used to represent the crosstalk influence on the initial microwave signal applied to the target qubit. Finally, it obtains the signal parameters of the crosstalk microwave signal transmitted on the drive line by square root processing of the target crosstalk matrix. This application does not require experimental testing. Through modeling and simulation, by inputting preset amplitude crosstalk coefficients and phase crosstalk coefficients and sequentially executing the above steps, the parameters of the crosstalk microwave signal under the influence of the crosstalk coefficients can be obtained. Compensation and calibration are then performed based on the determined crosstalk microwave signal parameters to ensure the operation accuracy of the quantum gate executed on the target qubit.

[0047] The methods for determining the operating frequency of qubits, the methods for determining the crosstalk coefficient of qubits, and the readable storage medium proposed in this application belong to the same concept as the method for determining the parameters of the crosstalk microwave signal of the qubit driving line mentioned above, and therefore have the same beneficial effects, which will not be elaborated here. Attached Figure Description

[0048] Figure 1 This is a schematic diagram illustrating the effect of adjacent qubit crosstalk as an example of an embodiment of this application;

[0049] Figure 2 This is a flowchart illustrating a method for determining the parameters of a crosstalk microwave signal for a qubit driving line according to an embodiment of this application.

[0050] Figure 3 This is a schematic diagram of a process for obtaining the amplitude crosstalk matrix of a target qubit according to an embodiment of this application;

[0051] Figure 4 This is a schematic diagram of a process for obtaining a voltage matrix and a phase matrix according to an embodiment of this application;

[0052] Figure 5 This is a schematic diagram of a process for obtaining the phase crosstalk matrix of a target qubit according to an embodiment of this application;

[0053] Figure 6 This is a flowchart illustrating a method for determining the operating frequency of a qubit according to an embodiment of this application.

[0054] Figure 7 This is a flowchart illustrating a method for determining the qubit crosstalk coefficient proposed in an embodiment of this application. Detailed Implementation

[0055] The specific embodiments of this application will be described in more detail below with reference to the schematic diagrams. The advantages and features of this application will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this application.

[0056] In the description of this application, it should be understood that the terms "center", "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0057] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0058] A quantum processor integrates multiple qubits, each with a corresponding driving line. Driving a qubit requires applying a driving signal (such as a microwave signal) to that driving line. Ideally, the driving signal applied to each qubit's driving line should only drive that specific qubit. However, in practical applications, the driving signal applied to each qubit's driving line can not only drive that qubit but also drive adjacent or nearby qubits through spatial radiation, affecting the driving of other qubits (crosstalk). Figure 1 The diagram shows the driving accuracy of two adjacent qubits. Crosstalk directly affects the driving accuracy of each qubit, and thus the computational accuracy of the qubits performing quantum computing tasks.

[0059] Figure 1 The diagram illustrates two qubits (Qubit1 and Qubit2), each with corresponding drive lines (Drive Line1 and Drive Line2). The drive lines are frequency drive lines for the qubits, and the microwave signals applied to these lines drive the qubits' operating frequency. The operating frequency of a qubit when performing an operation is called its operating point. When performing quantum gate operations, the operating frequency directly affects the precision of the qubit's operation. When microwave signals are applied to the frequency drive lines of other qubits, they directly affect the frequency of the current qubit, causing its operating frequency to shift and thus reducing its precision in performing quantum gate operations. Therefore, it is necessary to calibrate the microwave signals on the frequency drive lines of the qubits after crosstalk interference for calibration and compensation.

[0060] like Figure 2 As shown in the embodiment of this application, a method for determining the parameters of a crosstalk microwave signal transmitted on a qubit driving line is provided. The method includes the following steps.

[0061] Step S10: Obtain the voltage matrix and phase matrix of the initial microwave signal applied to the driving line of each qubit; wherein the number of rows and columns of the voltage matrix and phase matrix are the same as the number of qubits, and each column of the voltage matrix represents the voltage of a qubit, and each column of the phase matrix represents the phase of a qubit.

[0062] The microwave signal applied to the driving line of a qubit can be represented by the following formula:

[0063]

[0064] in, It is the constant voltage of the initial microwave signal, A j is the amplitude of the square envelope function of the initial microwave signal, and t is the pulse duration of the initial microwave signal. It is the frequency of the initial microwave signal applied to the drive line. It refers to the phase of the initial microwave signal applied to the drive line. In practice, an initial microwave signal is typically output by an instrument such as a signal source or microwave source and transmitted to the drive line of the qubit on the quantum processor through a quantum measurement and control link.

[0065] Among the parameters of the initial microwave signal mentioned above, the constant voltage, amplitude, and phase are the most susceptible to crosstalk. Therefore, when determining the parameters of the crosstalk microwave signal, the voltage matrix and phase matrix of the initial microwave signal applied to the driving line of each qubit should be determined first to facilitate the subsequent acquisition of the crosstalk voltage matrix and crosstalk phase matrix.

[0066] Specifically, an example of a voltage matrix is ​​as follows:

[0067]

[0068] The phase matrix described above is a square matrix, with the number of rows and columns equal to the number of qubits. For example, the first column represents the constant voltage and amplitude of the initial microwave signal applied to the driving line of the first qubit, the second column represents the constant voltage and amplitude of the initial microwave signal applied to the driving line of the second qubit, and so on, up to the last column representing the constant voltage and amplitude of the initial microwave signal applied to the driving line of the nth qubit, where n is the number of qubits. Furthermore, the voltage matrix described above consists of n rows, with the constant voltage and amplitude being the same in each row.

[0069] Specifically, an example of a phase matrix is ​​as follows:

[0070]

[0071] The phase matrix described above is a square matrix, with the number of rows and columns equal to the number of qubits. For example, the first column represents the phase of the initial microwave signal applied to the driving line of the first qubit, the second column represents the phase of the initial microwave signal applied to the driving line of the second qubit, and so on, up to the phase of the initial microwave signal applied to the driving line of the nth qubit in the last column, where n is the number of qubits. Furthermore, the voltage matrix described above consists of n rows, with all n rows having the same phase.

[0072] It should be added that the voltage matrix and phase matrix determined above are used to represent the voltage matrix and phase matrix of the initial microwave signal applied to the driving line of each qubit, and this voltage matrix and phase matrix do not include the effect of crosstalk.

[0073] Step S20: Multiply the preset amplitude crosstalk coefficient and voltage matrix to obtain the amplitude crosstalk matrix, and add the preset phase crosstalk coefficient and phase matrix to obtain the phase crosstalk matrix.

[0074] After determining the voltage matrix and phase matrix in step S10, the amplitude crosstalk matrix and phase crosstalk matrix after crosstalk influence can be determined according to the preset amplitude crosstalk coefficient and phase crosstalk coefficient. Specifically, the amplitude crosstalk matrix is ​​obtained by multiplying the preset amplitude crosstalk coefficient with the voltage matrix, and the phase crosstalk matrix is ​​obtained by adding the preset phase crosstalk coefficient with the phase matrix.

[0075] In practical implementation, after presetting the amplitude crosstalk coefficient for each qubit, the corresponding amplitude crosstalk coefficient matrix can be determined, represented as:

[0076]

[0077] Where R is an amplitude crosstalk coefficient matrix determined according to a preset amplitude crosstalk coefficient. Each column of the amplitude crosstalk coefficient matrix represents the amplitude crosstalk coefficient of the initial microwave signal applied to the driving line of one qubit to the driving lines of the other n qubits. When the number of qubits is n, the amplitude crosstalk coefficient matrix has n columns. For example, r 0→n The preset amplitude crosstalk coefficient is used to determine the effect of the amplitude of the initial microwave signal applied to the drive line of the 0th qubit on the amplitude crosstalk of the drive line of the nth qubit. 0→n This indicates the effect of the amplitude of the initial microwave signal applied to the driving line of the nth qubit on the amplitude crosstalk of the driving line of the 0th qubit.

[0078] After determining the amplitude crosstalk coefficient matrix based on the preset amplitude crosstalk coefficient, the amplitude crosstalk matrix can be obtained by multiplying the amplitude crosstalk coefficient matrix with the voltage matrix. An example is shown below:

[0079]

[0080] Where R⊙AV0 is the amplitude crosstalk matrix, and R is the amplitude crosstalk coefficient matrix mentioned above.

[0081] In practical implementation, after presetting the phase crosstalk coefficient for each qubit, the corresponding phase crosstalk coefficient matrix can be determined, represented as:

[0082]

[0083] in, The phase crosstalk coefficient matrix is ​​determined based on a preset phase crosstalk coefficient. Each column of the aforementioned phase crosstalk coefficient matrix represents the phase crosstalk coefficient of the initial microwave signal applied to the driving line of one qubit with respect to the driving lines of the other n qubits. When the number of qubits is n, the aforementioned phase crosstalk coefficient matrix has n columns. For example, The preset phase crosstalk coefficient is used to determine the phase crosstalk effect of the initial microwave signal applied to the driving line of the 0th qubit on the driving line of the nth qubit. This indicates the phase crosstalk effect of the initial microwave signal applied to the driving line of the nth qubit on the driving line of the 0th qubit.

[0084] After determining the phase crosstalk coefficient matrix based on the preset phase crosstalk coefficients, the phase crosstalk coefficient matrix is ​​obtained by adding the phase matrix. An example is shown below:

[0085]

[0086] The amplitude crosstalk matrix and phase crosstalk matrix determined above can represent the influence of amplitude crosstalk and phase crosstalk of the initial microwave signal applied to the driving line of the qubit on the initial microwave signal applied to the driving line of other qubits.

[0087] Step S30: Perform cosine processing on the phase crosstalk matrix to obtain the cosine phase function, and multiply the cosine phase function with the amplitude crosstalk matrix to obtain the target crosstalk matrix.

[0088] The phase crosstalk matrix described above can represent the phase crosstalk matrix of all qubits on the quantum processor. When analyzing the phase crosstalk on the driving line of each target qubit, it is necessary to select a row from the phase crosstalk matrix to represent the phase crosstalk of other qubits on the quantum processor to the driving line of the target qubit, and process it to obtain the phase crosstalk matrix of the target qubit.

[0089] like Figure 3 As shown, specifically, before obtaining the cosine phase function by cosine processing of the phase crosstalk matrix, the method also includes the following steps.

[0090] Step S201: Extract one row of the phase crosstalk coefficients used to characterize the target qubit from the phase crosstalk matrix as the first phase crosstalk matrix.

[0091] By extracting one row from the phase crosstalk matrix as the first phase crosstalk matrix, the phase crosstalk effect of microwave signals applied to the driving lines of other qubits on the driving line of the target qubit is characterized. For example, extracting any k-th row (where k is a positive integer less than n) represents the k-th target qubit, and the first phase crosstalk matrix is ​​expressed as:

[0092]

[0093] Step S202: Translate the first phase crosstalk matrix along the longitudinal direction to obtain the second phase crosstalk matrix.

[0094] For the first phase crosstalk matrix mentioned above A vertical translation and copying process is performed to form a second phase crosstalk matrix with n rows, as shown in the example:

[0095]

[0096] In the above, n equals the number of qubits.

[0097] Step S203: Transpose the first phase crosstalk matrix and translate it horizontally to obtain the third phase crosstalk matrix.

[0098] First, transpose the first phase crosstalk matrix. Then, copy the transposed matrix by horizontal translation to obtain the third phase crosstalk matrix. An example is shown below:

[0099]

[0100] Step S204: Obtain the phase crosstalk matrix of the target qubit by subtracting the second phase crosstalk matrix and the third phase crosstalk matrix.

[0101] The second and third phase crosstalk matrices are then subtracted, as shown in the example:

[0102]

[0103] The above Given the phase crosstalk matrix of the target qubit, cosine function processing is performed on the phase crosstalk matrix. Specifically, cosine processing is performed on each term in the phase crosstalk matrix of the target qubit to obtain the cosine phase function.

[0104] Example:

[0105]

[0106] After obtaining the cosine phase function of the target qubit, the cosine phase function is multiplied by the amplitude crosstalk matrix to obtain the target crosstalk matrix, as shown in the example:

[0107]

[0108] Among them, E k The target crosstalk matrix for the target qubit can represent the crosstalk effect on the microwave signal transmitted on the drive line of the target qubit.

[0109] Step S40: Perform square root processing on the target crosstalk matrix to obtain the signal parameters of the crosstalk microwave signal.

[0110] In step S30 above, after determining the crosstalk effect on the microwave signal transmitted on the drive line of the target qubit, E... k Then, by square rooting the signal, the signal parameters of the crosstalk microwave signal on the drive line can be obtained. Example:

[0111]

[0112] in, A is a constant voltage applied to the i-th qubit by the initial microwave signal. i r is the amplitude of the initial microwave signal applied to the i-th qubit. i→k Let r be the amplitude crosstalk effect of the initial microwave signal applied to the driving line of the i-th qubit on the driving line of the k-th qubit. z→k It is also an approximate definition; and Let φ represent the phase crosstalk coefficients of the i-th and z-th qubits, respectively. i→k It is the phase crosstalk effect of the initial microwave signal applied to the driving line of the i-th qubit on the driving line of the j-th qubit; It is also an approximate definition.

[0113] The crosstalk microwave signal parameters obtained after square root processing include the initial microwave signal parameters applied to the driving line of the target qubit, as well as the crosstalk influence parameters of the initial microwave signals applied to the driving lines of other qubits on that qubit. In other words, the parameters of the crosstalk microwave signal actually transmitted on the driving line of that qubit are determined. This enables the calibration and compensation of the crosstalk microwave signal on the driving line of the qubit after it has been affected by crosstalk.

[0114] It should be added that when the preset amplitude crosstalk coefficient and phase crosstalk coefficient in step S20 are different, the parameters of the crosstalk microwave signal finally obtained in step S40 will also be different. That is, the parameters of the crosstalk microwave signal actually transmitted on the driving line of the target quantum bit are closely related to the amplitude crosstalk coefficient and the phase crosstalk coefficient.

[0115] This application first determines the voltage and phase matrices of the initial microwave signal applied to each qubit as the initial matrices without crosstalk. Then, it processes the voltage and phase matrices according to preset amplitude and phase crosstalk coefficients to obtain amplitude and phase crosstalk matrices after crosstalk. Next, it performs cosine processing on the phase crosstalk matrix and multiplies the processed cosine phase function with the amplitude crosstalk matrix to obtain the target crosstalk matrix, which represents the crosstalk effect on the initial microwave signal applied to the target qubit. Finally, it performs square root processing on the target crosstalk matrix to obtain the parameters of the crosstalk microwave signal transmitted on the drive line. This application eliminates the need for experimental testing. Through modeling and simulation, by inputting preset amplitude and phase crosstalk coefficients and sequentially executing the above steps, the parameters of the crosstalk microwave signal under the influence of these crosstalk coefficients can be obtained. Compensation and calibration are then performed based on the determined parameters of the crosstalk microwave signal to ensure the operational accuracy of the quantum gates executed on the target qubit.

[0116] like Figure 4 As shown, as one implementation of this embodiment, the voltage matrix and phase matrix of the initial microwave signal applied to the driving line of each qubit are obtained, including the following steps.

[0117] Step S110: Obtain a voltage vector representing the voltage and amplitude of the initial microwave signal applied to the driving line of each qubit. As described in step S10 above, the initial microwave signal applied to the driving line of each qubit is fixed, and the voltage and amplitude of the initial microwave signal are also determined. The corresponding voltage vector can be obtained based on the voltage and amplitude, as shown in the example below:

[0118]

[0119] Where A0 represents the amplitude of the initial microwave signal applied to the driving line of the 0th qubit. This represents the constant voltage of the initial microwave signal applied to the driving line of the 0th qubit. It is a vector value.

[0120] Step S120: Translate the vector values ​​in the voltage vector to obtain the voltage matrix.

[0121] By performing a translation and copying process on the vector values ​​in the voltage vector in step S110 above, the aforementioned voltage matrix can be obtained.

[0122] Step S130: Obtain the phase value of the initial microwave signal applied to the driving line of each qubit and form a phase matrix; wherein the number of rows and columns of the voltage matrix and the phase matrix are the same as the number of qubits, and each column is used to represent the voltage vector or phase of a qubit.

[0123] The phase of the initial microwave signal applied by the driving line of the qubit can be expressed as:

[0124]

[0125] in, These represent the phases of the initial microwave signal applied to the 0th and nth qubits, respectively. For the above... Copy along the vertical direction to obtain the corresponding phase matrix.

[0126]

[0127] In step S20 above, the amplitude crosstalk matrix R⊙AV0 and the phase crosstalk matrix are determined. These are all crosstalk matrices of all qubits on the quantum processor. When analyzing the amplitude crosstalk on the driving line of each target qubit, it is necessary to select a row from the above amplitude crosstalk matrix to represent the amplitude crosstalk of other qubits on the quantum processor to the driving line of the target qubit, and process it to obtain the amplitude crosstalk matrix of the target qubit.

[0128] Therefore, as Figure 5 As shown, before multiplying the cosine phase function with the amplitude crosstalk matrix to obtain the target crosstalk matrix, the above method also includes the following steps.

[0129] Step S211: Extract one row of the amplitude crosstalk coefficients used to characterize the target qubit from the amplitude crosstalk matrix as the first amplitude crosstalk matrix.

[0130] By extracting one row from the amplitude crosstalk matrix as the first amplitude crosstalk matrix for the target qubit, the amplitude crosstalk effect of the initial microwave signal applied to the driving lines of other qubits on the driving line of the target qubit is characterized. For example, extracting any k-th row (where k is a positive integer less than n) represents the k-th target qubit, and the first amplitude crosstalk matrix is ​​expressed as:

[0131]

[0132] Step S212: Transpose the first amplitude crosstalk matrix to obtain the second amplitude crosstalk matrix.

[0133] Regarding the above AV0 k The transpose operation is performed to obtain the second amplitude crosstalk matrix, as shown in the example:

[0134]

[0135] Step S213: Obtain the product of the first amplitude crosstalk matrix and the second amplitude crosstalk matrix as the amplitude crosstalk matrix of the target qubit.

[0136] Example:

[0137]

[0138] The above (AV0) k ) T AV0 k This is used to represent the amplitude crosstalk matrix on the driving line of the target qubit.

[0139] Similarly, the phase crosstalk matrix described above can represent the phase crosstalk matrix of all qubits on the quantum processor. When analyzing the phase crosstalk on the driving line of each target qubit, it is necessary to select a row from the phase crosstalk matrix to represent the phase crosstalk of other qubits on the quantum processor to the driving line of the target qubit. Specifically, before performing cosine processing on the phase crosstalk matrix to obtain the cosine phase function, the method further includes: extracting a row from the phase crosstalk matrix used to characterize the phase crosstalk coefficients of the target qubit and performing transpose and translation processing to obtain the phase crosstalk matrix of the target qubit. The specific implementation process has been described in steps S201-204 above.

[0140] The cosine phase function obtained in step S30 above is the cosine phase function of the selected target qubit. Therefore, the target crosstalk matrix of the target qubit can be obtained by multiplying the cosine phase function of the target qubit with the amplitude crosstalk matrix of the target qubit. Then, the signal parameters of the crosstalk microwave signal transmitted on the driving line of the target qubit are obtained by taking the square root of the target crosstalk matrix of the target qubit.

[0141] It should be added that the amplitude crosstalk matrix R⊙AV0 determined above is the amplitude crosstalk matrix of all qubits on the quantum processor, while the amplitude crosstalk matrix (AV0) k ) T AV0 k The amplitude crosstalk matrix is ​​the target qubit's amplitude crosstalk matrix on the quantum processor; similarly, the phase crosstalk matrix... Let be the amplitude crosstalk matrix of all qubits on the quantum processor, and This is the phase crosstalk matrix of the target qubit on the quantum processor. In this embodiment, the amplitude crosstalk matrix and phase crosstalk matrix of all qubits on the quantum processor are first determined. Then, a row representing the crosstalk of the target qubit is extracted from the amplitude crosstalk matrix and the phase crosstalk matrix, respectively, and transposed and copied to obtain the amplitude crosstalk matrix and phase crosstalk matrix of the target qubit. Subsequent steps are then performed to obtain the signal parameters of the crosstalk microwave signal transmitted on the drive line of the target qubit.

[0142] like Figure 4 As shown, based on the same application concept, this embodiment also provides a method for determining the operating frequency of a qubit, including the following steps.

[0143] Step S11: Obtain the capacitance parameters of each qubit on the quantum processor, wherein the capacitance parameters include the qubit's own capacitance parameters and the coupling capacitance parameters between the qubit and the driving line.

[0144] Step S21: Obtain the signal parameters of the crosstalk microwave signal according to any of the methods described above.

[0145] Step S31: Determine the operating frequency of the quantum bit based on the capacitance parameters and signal parameters.

[0146] Specifically, the working frequency is determined as follows:

[0147]

[0148] in, For the operating frequency, Ω Qj For capacitance parameters, C Qj These are the signal parameters, which are determined as described in the above embodiments.

[0149]

[0150] Furthermore, the capacitance parameter of the qubit is determined as follows:

[0151]

[0152] in, These are coupling capacitor parameters. C j It is the capacitance parameter of the qubit itself. Let be Planck's constant. It is the characteristic magnitude of the charge zero-point fluctuation of a qubit.

[0153] like Figure 5 As shown, based on the same application concept, this embodiment also provides a method for determining the qubit crosstalk coefficient, including the following steps.

[0154] Step S12: Obtain the preset amplitude crosstalk coefficient and phase crosstalk coefficient of the qubit.

[0155] Step S22: Determine the operating frequency of the qubit using any of the methods described above, based on the amplitude crosstalk coefficient and the phase crosstalk coefficient.

[0156] Step S32: Perform a Rabi oscillation experiment on the qubit to obtain the measurement frequency of the qubit.

[0157] In this step, an experimental measurement method is adopted to perform a Rabi oscillation experiment on the target qubit and measure the measurement frequency of the qubit. The measurement frequency obtained by measurement is the measurement result under the influence of crosstalk; therefore, it can be compared with the operating frequency determined by calculation in step S22.

[0158] Step S42: Determine the amplitude crosstalk coefficient and phase crosstalk coefficient when the operating frequency is the same as the measurement frequency as the target crosstalk coefficient.

[0159] Specifically, the operating frequency of the qubit obtained in steps S12-S22 is under the influence of crosstalk, and the measurement frequency obtained in step S32 is also under the influence of crosstalk. Therefore, when comparing the operating frequency and the measurement frequency, the amplitude crosstalk coefficient and phase crosstalk coefficient defined in step S12 are the crosstalk coefficients of the qubit.

[0160] Based on the same concept, this embodiment also provides a readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it can determine the signal parameters of the crosstalk microwave signal transmitted on the drive line using the above-described method for determining microwave crosstalk on the qubit drive line, or determine the operating frequency of the qubit using the above-described method for determining the qubit operating frequency, or determine the crosstalk coefficient using the above-described method for determining the qubit crosstalk coefficient.

[0161] A readable storage medium can be a tangible device capable of holding and storing instructions for use by an instruction execution device, such as, but not limited to, electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination thereof. The computer programs described herein can be downloaded from the readable storage medium to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. Networks can include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. Each computing / processing device's network adapter card or network interface receives the computer program from the network and forwards it for storage on a readable storage medium within the respective computing / processing device. The computer program used to perform the operations of this application can be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as "C" or similar languages. The computer program can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuits, such as programmable logic circuits, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), are personalized by utilizing state information from a computer program. These electronic circuits can execute computer-readable program instructions to implement various aspects of this application.

[0162] Various aspects of this application are described herein with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by a computer program. These computer programs can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processor of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. These computer programs can also be stored in a readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner; thus, the readable storage medium storing the computer program includes an article of manufacture comprising instructions for implementing various aspects of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams.

[0163] A computer program may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the computer program executing on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.

[0164] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," or "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0165] The above are merely preferred embodiments of this application and do not constitute any limitation on this application. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in this application without departing from the scope of the technical solutions of this application shall still fall within the protection scope of this application.

Claims

1. A method for determining the parameters of a crosstalk microwave signal for a qubit driving line, characterized in that, include: Obtain the voltage matrix and phase matrix of the initial microwave signal applied to the driving line of each qubit; wherein the number of rows and columns of the voltage matrix and the phase matrix are the same as the number of qubits, and each column of the voltage matrix represents the voltage of a qubit, and each column of the phase matrix represents the phase of a qubit; The amplitude crosstalk matrix is ​​obtained by multiplying the voltage matrix with the preset amplitude crosstalk coefficient, and the phase crosstalk matrix is ​​obtained by adding the phase matrix with the preset phase crosstalk coefficient. The phase crosstalk matrix is ​​cosine processed to obtain a cosine phase function, and the cosine phase function is multiplied with the amplitude crosstalk matrix to obtain the target crosstalk matrix. The signal parameters of the crosstalk microwave signal are obtained by taking the square root of the target crosstalk matrix.

2. The method as described in claim 1, characterized in that, Obtain the voltage matrix and phase matrix of the initial microwave signal applied to the driving line of each qubit, including: Obtain a voltage vector representing the voltage and amplitude of the initial microwave signal applied to the drive line of each qubit; The voltage matrix is ​​obtained by horizontally shifting the vector values ​​in the voltage vector. The phase values ​​of the initial microwave signal applied to the driving line of each quantum bit are obtained, and a phase matrix is ​​formed.

3. The method as described in claim 1, characterized in that, Before multiplying the cosine phase function with the amplitude crosstalk matrix to obtain the target crosstalk matrix, the method further includes: Extract one row of amplitude crosstalk coefficients from the amplitude crosstalk matrix that characterizes the target qubit as the first amplitude crosstalk matrix; The first amplitude crosstalk matrix is ​​transposed to obtain the second amplitude crosstalk matrix; The product of the first amplitude crosstalk matrix and the second amplitude crosstalk matrix is ​​obtained as the amplitude crosstalk matrix of the target qubit.

4. The method as described in claim 1, characterized in that, Before performing cosine processing on the phase crosstalk matrix to obtain the cosine phase function, the method further includes: Extract one row from the phase crosstalk matrix that represents the phase crosstalk coefficient of the target qubit as the first phase crosstalk matrix; The second phase crosstalk matrix is ​​obtained by translating the first phase crosstalk matrix along the longitudinal direction. The first phase crosstalk matrix is ​​transposed and then translated laterally to obtain the third phase crosstalk matrix. The phase crosstalk matrix of the target qubit is obtained by subtracting the second phase crosstalk matrix from the third phase crosstalk matrix.

5. The method as described in claim 4, characterized in that, The target crosstalk matrix is ​​obtained by multiplying the cosine phase function with the amplitude crosstalk matrix, including: The target crosstalk matrix of the target qubit is obtained by multiplying the cosine phase function with the amplitude crosstalk matrix of the target qubit. The microwave signal parameters are obtained by square root processing of the target crosstalk matrix, including: The microwave signal parameters transmitted on the driving line of the target qubit are obtained by square rooting the target crosstalk matrix of the target qubit.

6. A method for determining the operating frequency of a qubit, characterized in that, include: Obtain the capacitance parameters of each qubit on the quantum processor, wherein the capacitance parameters include the qubit's own capacitance parameters and the coupling capacitance parameters between the qubit and the driving line; The signal parameters of the crosstalk microwave signal are obtained according to the method described in any one of claims 1-5; The operating frequency of the quantum bit is determined based on the capacitance parameters and the signal parameters.

7. The method as described in claim 6, characterized in that, The operating frequency is determined to be: Among them, the For the operating frequency, the Ω Qj For the capacitance parameter, C Qj The signal parameters are as described above.

8. The method as described in claim 7, characterized in that, The capacitance parameters are: in, These are coupling capacitor parameters. C j It is the capacitance parameter of the qubit itself. Let be Planck's constant. It is the characteristic magnitude of the charge zero-point fluctuation of a qubit.

9. A method for determining the crosstalk coefficient of a qubit, characterized in that, include: Obtain the amplitude crosstalk coefficient and phase crosstalk coefficient of the preset qubit; The operating frequency of the qubit is determined by the method described in any one of claims 6-8 based on the amplitude crosstalk coefficient and the phase crosstalk coefficient. The Rabi oscillation experiment was performed on the qubit to obtain the measurement frequency of the qubit; The amplitude crosstalk coefficient and phase crosstalk coefficient when the operating frequency is the same as the measurement frequency are determined as the target crosstalk coefficient.

10. A readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it can implement the method for determining microwave crosstalk on a qubit driving line as described in any one of claims 1-5 to determine the signal parameters of the crosstalk microwave signal transmitted on the driving line, or the method for determining the operating frequency of a qubit as described in any one of claims 6-8 to determine the operating frequency of the qubit, or the method for determining the crosstalk coefficient of a qubit as described in claim 9 to determine the crosstalk coefficient.

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