Quantum error mitigation method and device

Abstract

The invention provides a quantum error mitigation method and device, and the method comprises the steps: obtaining a sample quantum state through linear superposition of the results of a plurality of first unitary transformations which have a first probability and act on an accurate quantum state, constructing a quantum channel model, carrying out the inverse solution of the quantum channel model, obtaining a quasi-probability model, and carrying out the calculation of the quasi-probability model. The second initial state passes through a quantum circuit with noise to obtain an output quantum state, error correction is performed on the output quantum state by using a quantum error correction code method to obtain a quantum state to be subjected to error mitigation, and error mitigation is performed on the quantum state to be subjected to error mitigation by executing an operation process in a quasi-probability model on the quantum state to be subjected to error mitigation. According to the quantum error correction method, the number of physical bits required for realizing quantum error correction is reduced, the requirement on physical resources can be remarkably reduced on the premise of not sacrificing performance, so that the construction and maintenance of a quantum computing system are more economical and efficient, and higher computing accuracy can be kept under the conditions of higher noise and limited operation precision.

Description

Technical Field

[0001] One or more embodiments of this specification relate to the field of quantum computers, and more particularly, to a quantum error mitigation method and device. Background Art

[0002] With the rapid development of quantum computing technology, quantum computers have shown higher efficiency than traditional computers in solving specific types of problems. However, the physical implementation of quantum computers faces problems such as high error rate of quantum bits and easy interference of quantum states by the environment. Fault-tolerant quantum computing is a key research direction in the field of quantum computing, which aims to solve the error problem of quantum bits in the calculation process. Quantum bits are extremely fragile and easily interfered by the external environment, resulting in calculation errors, which seriously limits the practicality and reliability of quantum computing. In existing methods, quantum error correction codes can be used for error correction, but whether surface code error correction or color code error correction is used, to improve the error correction accuracy, more physical bits are required to encode a quantum bit, a large number of auxiliary quantum bits and complex quantum gate operations are required, which makes it difficult to implement in actual quantum computers. The above problems can also be solved by error mitigation technology. Existing error mitigation methods include zero noise extrapolation and quantum subspace expansion. These methods can achieve effective error mitigation under limited physical resource conditions, but they may encounter difficulties when dealing with quantum circuits with greater depth. As the depth of the circuit increases, the measurement variance increases exponentially, and the number of measurements increases exponentially, increasing the computational overhead. Summary of the invention

[0003] This application describes a quantum error mitigation method and device that can solve the above technical problems.

[0004] According to a first aspect, a quantum error mitigation method is provided for use in a quantum computer, the method comprising:

[0005] Constructing a quantum channel model, which represents a sample quantum state as a linear superposition of multiple first results obtained by applying multiple first unitary transformations, each with a first probability of occurrence, to an accurate quantum state, wherein the accurate quantum state is obtained by passing the first initial state through a noise-free quantum circuit, and the sample quantum state is obtained by passing the first initial state through a noisy quantum circuit;

[0006] The quantum channel model is inversely solved to obtain a quasi-probabilistic model, which represents the result quantum state after error mitigation as a linear superposition of multiple second results obtained by applying multiple second unitary transformations, each with a second probability of occurrence, to the quantum state to be error mitigated;

[0007] The second initial state is passed through the noisy quantum circuit to obtain an output quantum state, and the output quantum state is corrected using a quantum error correction code method to obtain a target quantum state. The target quantum state is used as the quantum state to be error-mitigated to perform the operation process in the quasi-probabilistic model to obtain a result quantum state of error mitigation.

[0008] In some embodiments, the second occurrence probability is obtained by using the first occurrence probability.

[0009] In some embodiments, the second unitary transform is an inverse operation of the first unitary transform.

[0010] In some embodiments, performing the operation process in the quasi-probabilistic model using the target quantum state as the quantum state to be error mitigated to obtain the error mitigated quantum state specifically includes:

[0011] A second unitary transformation is randomly selected according to the second occurrence probability, the target quantum state is operated using the second unitary transformation, the operation result is measured, and a result quantum state is obtained according to the measurement result.

[0012] In some embodiments, the expression of the quantum channel model is ,in, is the sample quantum state, i.e. the noisy quantum state, is an exact quantum state, is the first unitary transformation of the ith order, the first probability of occurrence is the probability of the ith first unitary transformation occurring, yes The conjugate transpose of .

[0013] In some embodiments, the expression of the quasi-probabilistic model is ,in, is the quantum state to be error-mitigated, is the resulting quantum state, is the ith second unitary transformation, the second probability of occurrence is the ith second unitary transformation The probability of occurrence, yes The conjugate transpose of is a normalization constant used to ensure the desired quantum state Satisfy the normalization condition of the density matrix, is a sign factor that adjusts the signs of the linear combination terms.

[0014] In some embodiments, the step of correcting the output quantum state using a quantum error correction code method to obtain a target quantum state specifically includes:

[0015] The output quantum state is encoded using a quantum error correction code, errors in the encoded output quantum state are detected by measuring auxiliary quantum bits, and errors in logical bits in the output quantum state are corrected using logical operations to obtain the target quantum state.

[0016] According to a second aspect, there is provided a quantum error mitigation device for use in a quantum computer, the device comprising:

[0017] A first processing module is used to construct a quantum channel model, which represents a sample quantum state as a linear superposition of multiple first results obtained by applying multiple first unitary transformations each having a first probability of occurrence to an accurate quantum state, wherein the accurate quantum state is obtained by passing a first initial state through a noise-free quantum circuit, and the sample quantum state is obtained by passing a first initial state through the quantum circuit with noise;

[0018] A second processing module is used to inversely solve the quantum channel model to obtain a quasi-probabilistic model, which represents the result quantum state after error mitigation as a linear superposition of second results of multiple second unitary transformations each having a second probability of occurrence acting on the quantum state to be error mitigated;

[0019] The third processing module is used to pass the second initial state through the quantum circuit with noise to obtain an output quantum state, correct the output quantum state using a quantum error correction code method to obtain a target quantum state, and use the target quantum state as the quantum state to be error-mitigated to execute the operation process in the quasi-probabilistic model to obtain a result quantum state of error mitigation.

[0020] In some embodiments, the second occurrence probability is obtained by using the first occurrence probability.

[0021] In some embodiments, the second unitary transform is an inverse operation of the first unitary transform.

[0022] In some embodiments, the first processing module is specifically used to randomly select one of the second unitary transformations according to the second occurrence probability, use the second unitary transformation to operate the target quantum state, measure the operation result, and obtain a result quantum state according to the measurement result.

[0023] In some embodiments, the expression of the quantum channel model is ,in, is the sample quantum state, i.e. the noisy quantum state, is an exact quantum state, is the first unitary transformation of the ith order, the first probability of occurrence is the probability of the ith first unitary transformation occurring, yes The conjugate transpose of .

[0024] In some embodiments, the expression of the quasi-probabilistic model is ,in, is the quantum state to be error-mitigated, is the resulting quantum state, is the ith second unitary transformation, the second probability of occurrence is the ith second unitary transformation The probability of occurrence, yes The conjugate transpose of is a normalization constant used to ensure that the resulting quantum state Satisfy the normalization condition of the density matrix, is a sign factor that adjusts the signs of the linear combination terms.

[0025] In some embodiments, the third processing module is specifically used to encode the output quantum state using a quantum error correction code, detect errors in the encoded output quantum state by measuring auxiliary quantum bits, and use logical operations to correct errors in logical bits in the output quantum state to obtain the target quantum state.

[0026] According to a third aspect, a computer storage medium is provided, on which a computer program is stored. When the computer program is executed by one or more processors, a quantum error mitigation method as described in any one of the above technical solutions is implemented.

[0027] According to a fourth aspect, an electronic device is provided, comprising a memory and one or more processors, wherein a computer program is stored in the memory, and when the computer program is executed by the one or more processors, a quantum error mitigation method as described in any one of the above technical solutions is implemented.

[0028] In the above-mentioned system and method provided in the embodiments of this specification, the number of physical bits required to implement quantum error correction is reduced through the quasi-probabilistic model. Compared with traditional quantum error correction codes, it is possible to significantly reduce the demand for physical resources without sacrificing performance, making the construction and maintenance of quantum computing systems more economical and efficient, and maintaining high computing accuracy under conditions of high noise and limited operating precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1A schematic diagram of a quantum circuit showing a quantum error mitigation method implemented by a quantum circuit provided in an embodiment of this specification; Figure 2 A schematic diagram showing a flow chart of a quantum error mitigation method provided in an embodiment of this specification; Figure 3 A schematic diagram showing a quantum error mitigation device provided in an embodiment of this specification. DETAILED DESCRIPTION

[0031] The solution provided in this specification is described below in conjunction with the accompanying drawings.

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0033] In the description of the embodiments of the present application, words such as "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a concrete way.

[0034] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, B exists alone, and A and B exist at the same time. In addition, unless otherwise specified, the term "plurality" means two or more.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. The terms "include", "comprises", "has" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0036] Quantum bits are extremely fragile and easily interfered by the external environment, resulting in calculation errors, which severely limits the practicality and reliability of quantum computing. Because the quantum no-cloning principle prohibits the direct copying of quantum information, the traditional error correction method is no longer applicable in the quantum world. The first existing method is to use the surface code error correction method, through the quantum bit array on the two-dimensional grid, using the stable sub measurement on the grid to detect and correct errors. This method is very effective in the case of a large number of quantum bits, but requires complex quantum circuits and high-precision quantum operations. The second existing method is to use the color code error correction method, by constructing a three-dimensional grid and using the topological properties of the grid to achieve error correction. Color codes can achieve more efficient error correction, but also require a lot of physical resources and complex operations. In summary, to improve the error correction accuracy of the existing methods, it is necessary to increase the code distance of the error correction code, which will require more physical bits to encode a quantum bit, which will require a lot of physical resources, including auxiliary quantum bits and complex quantum gate operations, making it difficult to implement in actual quantum computers.

[0037] At present, error mitigation technology is another strategy for quantum error correction methods, which reduces errors in quantum computing through statistical analysis and post-processing algorithms. Specific error mitigation methods include zero noise extrapolation and quantum subspace expansion. These methods can achieve effective error mitigation under limited physical resource conditions, but may encounter difficulties when dealing with quantum circuits with greater depth. As the depth of the circuit increases, the measurement variance increases exponentially, and the number of measurements increases exponentially, increasing the computational overhead.

[0038] In view of this, the present invention proposes a quantum error mitigation method, which can solve the problem that when using an error correction code method, more physical bits are needed to encode a quantum bit to improve the error correction accuracy, and the existing error mitigation method increases the number of measurements exponentially when processing a quantum circuit with a large depth. Figure 1 FIG. 1 is a schematic diagram showing a method for implementing quantum error mitigation in a quantum circuit according to the present invention. Figure 1 As shown, the process of quantum error mitigation in quantum circuits may include the following five stages / steps.

[0039] Step 1 is the encoding process of quantum error correction code. Quantum error correction code encodes the quantum state by encoding a single logical quantum bit into multiple physical quantum bits.

[0040] Step 2 is to perform logical operations on the encoded quantum state through quantum circuits. The logical operations are expressed as In this step, logical operations are performed on the encoded quantum state in the quantum circuit. The quantum circuit here is a noisy quantum circuit. Through the operation and processing of the quantum circuit, the converted quantum state is obtained.

[0041] In step 3, it is detected whether there are errors in the converted quantum state, and if errors are detected, corresponding logical operations are applied to correct these errors.

[0042] In step 4, the operation process in the quasi-probabilistic model is performed on the error-corrected quantum state to mitigate the quantum state errors. The construction of the quasi-probabilistic model and its operation process will be described in detail below.

[0043] Step 5, after measuring the quantum state obtained in the previous step multiple times, calculate the measurement average value, and obtain the final result based on the average value of multiple measurements.

[0044] This embodiment achieves quantum error mitigation through a quasi-probabilistic model method, reduces the number of physical bits required in traditional error correction code methods, and significantly reduces the demand for physical resources without sacrificing performance, making the construction and maintenance of quantum computing systems more economical and efficient. It is particularly suitable for early fault-tolerant computing devices. Even under conditions of high noise and limited operating accuracy, it can maintain high computing accuracy, greatly expanding the application scope of quantum computing technology. By modeling and statistically analyzing the error characteristics of quantum operations, the accuracy of quantum computing results can be significantly improved. It does not rely on complex high-code distance error correction codes and is easier to expand to larger-scale quantum systems. It can be applied to different types of quantum computers, including superconducting quantum bits, ion trap quantum bits, and other types of quantum bit systems. Due to the reduced demand for physical resources, the computing cost is reduced.

[0045] Combine the following Figure 2 The flowchart of the quantum error mitigation method shown is described in detail, specifically including:

[0046] 110. Construct a quantum channel model, which represents a sample quantum state as a linear superposition of multiple first results obtained by applying multiple first unitary transformations, each with a first probability of occurrence, to a precise quantum state, wherein the precise quantum state is obtained by passing the first initial state through a noise-free quantum circuit, and the sample quantum state is obtained by passing the first initial state through a noisy quantum circuit.

[0047] Specifically, the expression of the quantum channel model can be the following formula (1):

[0048] (1)

[0049] in, It is the sample quantum state, i.e. the noisy quantum state, which is the quantum state obtained after a certain initial state passes through a noisy quantum circuit. is the precise quantum state, which is the quantum state obtained by assuming that the initial state passes through a quantum circuit that executes the same logic but without noise. is the first unitary transformation of the ith order, the first probability of occurrence is the probability of the ith first unitary transformation occurring, yes The conjugate transpose of .

[0050] It can be seen that the quantum channel model converts the sample quantum state Represented as multiple, each with a first probability of occurrence The first unitary transformation Acting on precise quantum states The linear superposition of the multiple first results is obtained.

[0051] 120. The quantum channel model is inversely solved to obtain a quasi-probabilistic model, which represents the result quantum state after error mitigation as a linear superposition of multiple second results obtained by applying multiple second unitary transformations, each with a second probability of occurrence, to the quantum state to be error mitigated.

[0052] Specifically, the second occurrence probability can be obtained through the first occurrence probability.

[0053] In some applications, the second unitary transform is the inverse operation of the first unitary transform.

[0054] Specifically, the expression of the quasi-probabilistic model can be shown as formula (2):

[0055] (2)

[0056] in, is the quantum state to be error-mitigated, which corresponds to the sample quantum state in the aforementioned formula 1, i.e., the noisy quantum state. is the resulting quantum state after error mitigation, which corresponds to the exact quantum state in the aforementioned formula 1. is the ith second unitary transformation, the second probability of occurrence is the ith second unitary transformation The probability of occurrence, yes The conjugate transpose of is a normalization constant used to ensure the desired quantum state Satisfy the normalization condition of the density matrix, is the sign factor, used to adjust the sign of the linear combination term, , .

[0057] It can be seen that the quasi-probabilistic model is the reverse expression of the quantum channel model. That is, the quantum channel model expresses the quantum state (i.e., the aforementioned sample quantum state) that may contain errors obtained by the noisy quantum circuit as a function of the precise quantum state; while the quasi-probabilistic model expresses the precise quantum state (the result quantum state after error mitigation) as a function of the quantum state to be error-mitigated. Specifically, the quasi-probabilistic model expresses the result quantum state after error mitigation as a linear superposition of multiple second results obtained by applying multiple second unitary transformations, each with a second probability of occurrence, to the quantum state to be error-mitigated.

[0058] Specifically, the method for inversely solving the quantum channel model includes constructing a quasi-probabilistic model through quantum process tomography. The functional form of Determine the second unitary transformation , according to the i-th first unitary transformation The probability of occurrence determines the second unitary transformation The probability of occurrence, calculate the normalization constant , according to the characteristics of the noise and the effect of the unitary transformation, adjust the sign factor .

[0059] When implementing the above steps on actual quantum hardware, the effect of the inversion can be verified by collecting the resulting data, and the quasi-probability model can be further optimized by iteratively adjusting the unitary transformation, quasi-probability, and sign factors.

[0060] 130. The second initial state is passed through a noisy quantum circuit to obtain an output quantum state. The output quantum state is corrected using a quantum error correction code method to obtain a target quantum state. The target quantum state is used as the quantum state to be error-mitigated to perform the operation process in the quasi-probabilistic model to obtain a result quantum state of error mitigation.

[0061] Specifically, Figure 1 As shown, the second initial state is quantum-encoded using a quantum error correction code, and the encoded quantum state is input into a quantum circuit containing noise to obtain an output quantum state; the output quantum state is error-corrected by measuring the auxiliary quantum bit detection error to obtain a corrected logical bit. The quantum state at this time is recorded as the target quantum state. It can be understood that even after correction, the target quantum state still has errors and needs error mitigation.

[0062] Therefore, the target quantum state can be used as the quantum state to be error-mitigated in the quasi-probabilistic model, and the operation process in the quasi-probabilistic model is performed on it to obtain the error-mitigated result quantum state.

[0063] Specifically, on a quantum computer, using a classical random number generator, according to the second probability Randomly select a second unitary transformation And execute, that is, the second unitary transformation Apply to the target quantum state to be error-mitigated, measure the execution result, and obtain the measurement result. Multiply each measurement result by the corresponding sign factor , to reverse the effect of noise. All measurements are summed and multiplied by the normalization constant , and obtain the desired quantum state.

[0064] After the unitary transformation is performed, the quantum state is measured. Since the measurement results are affected by the selected unitary transformation, all measurement results can be collected by repeating the procedure multiple times and then sorted according to their probabilities. After weighted averaging, the final quantum state is obtained.

[0065] The following is an illustration of a specific case.

[0066] In this example, it is assumed that the initial state , the error correction code is a simple 3-qubit repetition code, namely , , logical operation Pauli operation, the noise channel is a depolarized noise line , is the error rate. Assume that the observable quantity to be measured is . Combined Figure 1 The relevant steps to mitigate quantum errors are as follows.

[0067] In step 1, quantum error correction codes are used to convert the physical bits Mapped to logical bits , the quantum state is encoded.

[0068] In step 2, a logical operation is performed based on the noisy quantum circuit N. At this time, the line noise has been taken into account. That is, the above logic bits are After that, the output quantum state is obtained: .

[0069] In step 3, the line is error detected and corrected to obtain the corrected logic bit. At this time, even the corrected logic bit still has errors. Assume that the quantum state obtained at this time is expressed by the quantum channel model as: in, is the exact quantum state. In this case, the exact quantum state , the sample quantum state at this time .

[0070] In step 4, the corrected logical bits are subjected to error mitigation using a quasi-probabilistic model. The quasi-probabilistic model is obtained by inversely solving the quantum channel model, and is specifically expressed as:

[0071]

[0072] Applied to this example, it is expressed as ,

[0073] in, , , .

[0074] The above formula indicates that the process of error mitigation operation of the quasi-probabilistic model includes: The probability is transformed to The probability of performing zero transformation is as follows. The identity transformation and zero transformation are the specific implementations of the aforementioned second unitary transformation in this example.

[0075] For other initial states Depolarized Noise Line , the quantum state to be processed is obtained, and the error correction code is a simple 3-qubit repetition code, that is , After encoding the quantum state to be processed, the encoded quantum state is subjected to Pauli Operations are performed to detect and correct quantum state errors and obtain quantum states after error correction. Quasi-probabilistic models are applied to quantum states after error correction. , respectively The probability performs an identity transformation, Probability performs zeroing transformation and obtains the resulting quantum state.

[0076] In step 5, the resulting quantum state is measured, and the average value is calculated after multiple measurements. The result is multiplied by That is, you can get the final result.

[0077] This embodiment achieves quantum error mitigation through a quasi-probabilistic model method, reduces the number of physical bits required in traditional error correction code methods, and significantly reduces the demand for physical resources without sacrificing performance, making the construction and maintenance of quantum computing systems more economical and efficient. It is particularly suitable for early fault-tolerant computing devices. Even under conditions of high noise and limited operating accuracy, it can maintain high computing accuracy, greatly expanding the application scope of quantum computing technology. By modeling and statistically analyzing the error characteristics of quantum operations, the accuracy of quantum computing results can be significantly improved. It does not rely on complex high-code distance error correction codes and is easier to expand to larger-scale quantum systems. It can be applied to different types of quantum computers, including superconducting quantum bits, ion trap quantum bits, and other types of quantum bit systems. Due to the reduced demand for physical resources, the computing cost is reduced.

[0078] like Figure 3 A quantum error mitigation device is shown, which is used in a quantum computer, and the device comprises:

[0079] A first processing module is used to construct a quantum channel model, which represents a sample quantum state as a linear superposition of multiple first results obtained by applying multiple first unitary transformations each having a first probability of occurrence to an accurate quantum state, wherein the accurate quantum state is obtained by passing a first initial state through a noise-free quantum circuit, and the sample quantum state is obtained by passing a first initial state through the quantum circuit with noise;

[0080] A second processing module is used to inversely solve the quantum channel model to obtain a quasi-probabilistic model, which represents the result quantum state after error mitigation as a linear superposition of second results of multiple second unitary transformations each having a second probability of occurrence acting on the quantum state to be error mitigated;

[0081] The third processing module is used to pass the second initial state through the quantum circuit with noise to obtain an output quantum state, correct the output quantum state using a quantum error correction code method to obtain a target quantum state, and use the target quantum state as the quantum state to be error-mitigated to execute the operation process in the quasi-probabilistic model to obtain a result quantum state of error mitigation.

[0082] In some embodiments, the second occurrence probability is obtained by using the first occurrence probability.

[0083] In some embodiments, the second unitary transform is an inverse operation of the first unitary transform.

[0084] In some embodiments, the first processing module is specifically used to randomly select one of the second unitary transformations according to the second occurrence probability, use the second unitary transformation to operate the target quantum state, measure the operation result, and obtain a result quantum state according to the measurement result.

[0085] In some embodiments, the expression of the quantum channel model is ,in, is the sample quantum state, is an exact quantum state, is the first unitary transformation of the ith order, the first probability of occurrence is the probability of the ith first unitary transformation occurring, yes The conjugate transpose of .

[0086] In some embodiments, the expression of the quasi-probabilistic model is ,in, is the quantum state to be error-mitigated, is the resulting quantum state, is the ith second unitary transformation, the second probability of occurrence is the ith second unitary transformation The probability of occurrence, yes The conjugate transpose of is a normalization constant used to ensure the desired quantum state Satisfy the normalization condition of the density matrix, is a sign factor that adjusts the signs of the linear combination terms.

[0087] In some embodiments, the third processing module is specifically used to encode the output quantum state using a quantum error correction code, detect errors in the encoded output quantum state by measuring auxiliary quantum bits, and use logical operations to correct errors in logical bits in the output quantum state to obtain the target quantum state.

[0088] This embodiment achieves quantum error mitigation through a quasi-probabilistic model method, reduces the number of physical bits required in traditional error correction code methods, and significantly reduces the demand for physical resources without sacrificing performance, making the construction and maintenance of quantum computing systems more economical and efficient. It is particularly suitable for early fault-tolerant computing devices. Even under conditions of high noise and limited operating accuracy, it can maintain high computing accuracy, greatly expanding the application scope of quantum computing technology. By modeling and statistically analyzing the error characteristics of quantum operations, the accuracy of quantum computing results can be significantly improved. It does not rely on complex high-code distance error correction codes and is easier to expand to larger-scale quantum systems. It can be applied to different types of quantum computers, including superconducting quantum bits, ion trap quantum bits, and other types of quantum bit systems. Due to the reduced demand for physical resources, the computing cost is reduced.

[0089] The present invention also provides a computer storage medium, on which a computer program is stored. When the computer program is executed by one or more processors, the quantum error mitigation method as described in any one of the above technical solutions is implemented.

[0090] The present invention also provides an electronic device, comprising a memory and one or more processors, wherein the memory stores a computer program, and when the computer program is executed by the one or more processors, the quantum error mitigation method as described in any one of the above technical solutions is implemented.

[0091] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation methods of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solutions of the present application should be included in the scope of protection of the present application.

Claims

1. A quantum error mitigation method, characterized in that: For use in a quantum computer, the method comprises: Constructing a quantum channel model, which represents a sample quantum state as a linear superposition of multiple first results obtained by applying multiple first unitary transformations, each with a first probability of occurrence, to an accurate quantum state, wherein the accurate quantum state is obtained by passing the first initial state through a noise-free quantum circuit, and the sample quantum state is obtained by passing the first initial state through a noisy quantum circuit; The quantum channel model is inversely solved to obtain a quasi-probabilistic model, which represents the result quantum state after error mitigation as a linear superposition of multiple second results obtained by applying multiple second unitary transformations, each with a second probability of occurrence, to the quantum state to be error mitigated; The second initial state is passed through the noisy quantum circuit to obtain an output quantum state, and the output quantum state is corrected using a quantum error correction code method to obtain a target quantum state. The target quantum state is used as the quantum state to be error-mitigated to perform the operation process in the quasi-probabilistic model to obtain a result quantum state of error mitigation.

2. The method according to claim 1, characterized in that: The second occurrence probability is obtained through the first occurrence probability.

3. The method according to claim 1, characterized in that The second unitary transform is an inverse operation of the first unitary transform.

4. The method according to claim 1, characterized in that: The step of executing the operation process in the quasi-probabilistic model using the target quantum state as the quantum state to be error mitigated to obtain the error mitigated quantum state specifically includes: A second unitary transformation is randomly selected according to the second occurrence probability, the target quantum state is operated using the second unitary transformation, the operation result is measured, and a result quantum state is obtained according to the measurement result.

5. The method according to claim 1, characterized in that The expression of the quantum channel model is ,in, is the sample quantum state, i.e. the noisy quantum state, is an exact quantum state, It is i The first unitary transformation, the first probability of occurrence It is i The probability of the first unitary transformation occurring is yes The conjugate transpose of .

6. The method according to claim 1, characterized in that The expression of the quasi-probabilistic model is ,in, is the quantum state to be error-mitigated, is the resulting quantum state, It is i The second unitary transformation, the second probability of occurrence It is i Second Unitary Transformation The probability of occurrence, yes The conjugate transpose of is a normalization constant used to ensure that the resulting quantum state satisfies the normalization condition of the density matrix, is a sign factor that adjusts the signs of the linear combination terms.

7. The method according to claim 1, characterized in that After the output quantum state is corrected using a quantum error correction code method, a target quantum state is obtained, which specifically includes: The output quantum state is encoded using a quantum error correction code, errors in the encoded output quantum state are detected by measuring auxiliary quantum bits, and errors in logical bits in the output quantum state are corrected using logical operations to obtain the target quantum state.

8. A quantum error mitigation device, characterized in that: For use in a quantum computer, the device comprises: A first processing module is used to construct a quantum channel model, which represents a sample quantum state as a linear superposition of multiple first results obtained by applying multiple first unitary transformations each having a first probability of occurrence to an accurate quantum state, wherein the accurate quantum state is obtained by passing a first initial state through a noise-free quantum circuit, and the sample quantum state is obtained by passing a first initial state through the quantum circuit with noise; A second processing module is used to inversely solve the quantum channel model to obtain a quasi-probabilistic model, which represents the result quantum state after error mitigation as a linear superposition of second results of multiple second unitary transformations each having a second probability of occurrence acting on the quantum state to be error mitigated; The third processing module is used to pass the second initial state through the quantum circuit with noise to obtain an output quantum state, correct the output quantum state using a quantum error correction code method to obtain a target quantum state, and use the target quantum state as the quantum state to be error-mitigated to execute the operation process in the quasi-probabilistic model to obtain a result quantum state of error mitigation.

9. A computer storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by one or more processors, the quantum error mitigation method according to any one of claims 1 to 7 is implemented.

10. An electronic device, characterized in that: The method comprises a memory and one or more processors, wherein a computer program is stored in the memory, and when the computer program is executed by the one or more processors, the quantum error mitigation method according to any one of claims 1 to 7 is implemented.

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