Quantum circuit simulation method, device, computer device, and computer program

Abstract

The present application discloses a quantum circuit simulation method and apparatus, a computer device, a storage medium, and a program product, the method including the steps of: obtaining a polynomial obtained by converting a UCC factor in exponential form; and converting G, an exponential part of the UCC factor, into a polynomial through the above conversion, wherein the polynomial includes a first-order term and a second-order term of G; obtaining N UCC factors for constructing a UCC quantum circuit; and performing UCC quantum circuit quantum simulation based on the wave function and the UCC factors to obtain a resultant wave function, wherein the quantum simulation is used to calculate each UCC factor with the wave function in the form of the polynomial.

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application bearing application number 202310113388.5, filed with the China Patent Office on January 30, 2023, the entire contents of which are incorporated herein by reference. The present application relates to the quantum field, and in particular to quantum circuit methods and devices, computer devices, storage media, and program products. [Background technology]

[0002] A quantum circuit is a representation of a quantum general-purpose computer and represents the hardware realization of a corresponding quantum algorithm / program in the quantum gate model. A quantum circuit operates on a quantum state to obtain a new quantum state and perform a quantum computation. If a quantum circuit contains adjustable parameters for controlling the quantum gates, it is also called a parameterized quantum circuit (PQC) or variational quantum circuit. For example, a unitary coupled-cluster (UCC) quantum circuit is a special type of parameterized quantum circuit, primarily used for quantum computation of the chemical properties of molecular systems.

[0003] JPEG2025529955000002.jpg66170 Summary of the Invention [Problem to be solved by the invention]

[0004] To solve the above technical problems, the embodiments of the present application provide a quantum circuit simulation method and apparatus, a computer device, a storage medium, and a program product that effectively improve the efficiency of quantum simulation and achieve the effect of quickly and easily determining the quantum state of an object corresponding to a UCC quantum circuit. The embodiments of the present application disclose the following technical solutions: On the other hand, an embodiment of the present application provides a quantum circuit simulation method applied to a computer device, the method comprising: a step of transforming a UCC factor to obtain a polynomial, the exponent of which includes an anti-Hermitian excitation operator G, and the polynomial includes first-order and second-order terms of G; obtaining N UCC factors for constructing a UCC quantum circuit, where N is an integer and N>1; obtaining a wave function, said wave function being used to represent a quantum state of an object; performing a quantum simulation on the UCC quantum circuit based on the wave function and the N UCC factors to obtain a resultant wave function, wherein the quantum simulation is used to operate each UCC factor with the wave function in the form of a polynomial, and the resultant wave function is used to represent the quantum state of the object simulated by the UCC quantum circuit. On the other hand, an embodiment of the present application provides a quantum circuit simulation apparatus, the apparatus comprising: an obtaining unit, a determining unit, and a simulation unit; The obtaining unit is configured to obtain a polynomial obtained by transforming a UCC factor, where an exponent part of the UCC factor includes an anti-Hermitian excitation operator G, and the polynomial includes a first-order term and a second-order term of G; The determination unit is configured to obtain N UCC factors for constructing a UCC quantum circuit and obtain a wave function, the wave function being used to represent a quantum state of an object corresponding to the UCC quantum circuit, where N is an integer and N>1; The simulation unit is configured to perform a quantum simulation on the UCC quantum circuit based on the wave function and the N UCC factors to obtain a resultant wave function, the quantum simulation being used to operate each UCC factor with the wave function in the form of the polynomial, and the resultant wave function being used to represent the quantum state of the object simulated by the UCC quantum circuit.

[0005] On the other hand, an embodiment of the present application provides a computer device, the computer device comprising a processor and a memory, the memory is configured to store program code and to transmit the program code to the processor; The processor is configured to perform the quantum circuit simulation method described above according to instructions in the program code. On the other hand, an embodiment of the present application provides a computer-readable storage medium, the computer-readable storage medium storing a computer program, the computer program executing the quantum circuit simulation method described above. On the other hand, embodiments of the present application provide a computer program product including instructions, which when executed on a computer, cause the computer to perform the quantum circuit simulation method described above.

[0006] As can be seen from the above technical solution, a wave function for constructing an object quantum state corresponding to a UCC quantum circuit to be simulated and N UCC factors representing the UCC quantum circuit are obtained by converting the UCC factors in exponential form to obtain a polynomial containing linear and quadratic terms of G. When performing quantum simulation on the circuit based on the wave function and UCC factors, each UCC factor is calculated with the wave function in polynomial form, and a resultant wave function is finally obtained through quantum simulation. In the above calculation process, because the polynomial is converted from exponential form to linear and quadratic terms of G, the calculation complexity of the wave function and UCC factors in the quantum simulation is significantly reduced compared to calculation in exponential form. This eliminates the need to decompose the UCC factors into quantum gates for quantum simulation, effectively improving the efficiency of quantum simulation and achieving the effect of quickly and easily determining the quantum state of an object corresponding to a UCC quantum circuit. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a quantum circuit obtained by performing quantum gate decomposition on a UCC factor. [Figure 2] FIG. 1 is a schematic diagram of a quantum circuit simulation scene according to an embodiment of the present application; [Figure 3] 1 is a flowchart of a quantum circuit simulation method according to an embodiment of the present application. [Figure 4] 1 is a schematic diagram according to an embodiment of the present application; [Figure 5] 1 is a schematic diagram of a wave function of a chemical molecule represented in configuration space according to an embodiment of the present application. FIG. [Figure 6] FIG. 1 is a schematic diagram for realizing the operation of an operator G and a wave function by vector feature rearrangement and phase transformation according to an embodiment of the present application. [Figure 7] FIG. 10 is a diagram comparing effects in an example of quantum simulation according to an embodiment of the present application. [Figure 8] 1 is a configuration diagram of a quantum circuit simulation device according to an embodiment of the present application. [Figure 9]FIG. 1 is a diagram illustrating the configuration of a terminal device according to an embodiment of the present application. [Figure 10] FIG. 2 is a diagram illustrating the configuration of a server according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0008] In order to more clearly describe the technical solutions in the embodiments of the present application or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced above. Obviously, the above drawings are some embodiments of the present application, and those skilled in the art can also obtain other related drawings based on these drawings without any creative efforts.

[0009] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. The described embodiments do not limit the present application, and all other embodiments that can be obtained by those skilled in the art without any creative efforts are included in the protection scope of the present application.

[0010] In the following description, the term "some embodiments" describes a subset of all possible embodiments, but it is understood that "some embodiments" may be the same or different subsets of all possible embodiments and may be combined with each other without conflict.

[0011] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. The terms used herein are used only to describe the embodiments of the present application and are not intended to limit the present application.

[0012] Hereinafter, the present embodiment will be described with reference to the drawings.

[0013] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. The terms used herein are used only to describe the embodiments of the present application and are not intended to limit the present application.

[0014] Before describing the embodiments of the present application in detail, the nouns and terms related to the embodiments of the present application will be explained. The explanation of the nouns and terms related to the embodiments of the present application is as follows.

[0015] 1) Quantum Circuit: A quantum general-purpose computer is a hardware implementation of a quantum algorithm / program based on the quantum gate model. Quantum circuits operate on quantum states to obtain new quantum states and perform quantum computations. If a quantum circuit contains adjustable parameters for controlling quantum gates, it is also called a parameterized quantum circuit (PQC) or variational quantum circuit. For example, a unitary coupled-cluster (UCC) quantum circuit is a special type of parameterized quantum circuit, primarily used for quantum computation of chemical properties of molecular systems.

[0016] 2) Quantum simulation: Simulating the dynamics and evolution of quantum systems using quantum computers. Quantum simulation allows us to quickly simulate the results of UCC quantum circuits, i.e., the resulting wave functions.

[0017] 3) Quantum Computation: A computational method that utilizes properties such as quantum superposition and entanglement to quickly complete computational tasks.

[0018] 4) Qubit: A representation of quantum information. In quantum computing, a qubit is used as a unit of quantum information, which is similar to a classical bit but with the quantum properties of a physical atom.

[0019] 5) Quantum Gate: A basic quantum circuit for operating a small number of quantum bits. Quantum gates are the basis of quantum circuits, and the relationship between them is similar to that between logic gates and digital circuits. Quantum gates operate on one quantum bit or two quantum bits; a quantum gate that operates on one quantum bit is a single-qubit gate, and a quantum gate that operates on two quantum bits is a double-qubit gate. Some quantum gates and their definitions are shown in Table 1 below.

[0020] [Table 1]

[0021] JPEG2025529955000004.jpg40170

[0022] JPEG2025529955000005.jpg22170

[0023] JPEG2025529955000006.jpg38170

[0024] JPEG2025529955000007.jpg37170

[0025] 11) Wave function: In a broad sense, a wave function is a quantum state. In a narrow sense, a wave function is a representation of a quantum state in the coordinate representation.

[0026] JPEG2025529955000008.jpg60170

[0027] JPEG2025529955000009.jpg33170

[0028] In a classical simulation, the effect of each quantum gate on a quantum state is realized as a single matrix-vector multiplication, so the more quantum gates there are, the more matrix multiplications a classical simulation requires.

[0029] As can be seen, the quantum gate decomposition method requires a large amount of calculation and computational complexity due to the UCC factors.

[0030] Therefore, the embodiments of the present application provide a quantum circuit simulation method that effectively improves the efficiency of quantum simulation and can quickly and easily determine the quantum state of an object corresponding to a UCC quantum circuit.

[0031] The quantum circuit simulation method provided in the embodiments of the present application may be implemented by a computer device, and the computer device may be a terminal device or a server, where the server may be an independent physical server, a server cluster or a distributed system composed of multiple physical servers, or a cloud server providing cloud computing services. Terminal devices include, but are not limited to, mobile phones, computers, intelligent voice dialogue devices, smart home appliances, in-vehicle terminals, aircraft, etc. The terminal device and the server may be directly or indirectly connected via wired or wireless communication, and the embodiments of the present application are not limited thereto.

[0032] 2 is a schematic diagram of a quantum circuit simulation scene according to an embodiment of the present application. In the embodiment of the present application, the server 100 is described as the above-mentioned computer device. To reduce the computational complexity of the quantum simulation, the server 100 can obtain a polynomial by converting the UCC factors in exponential form, and converting the exponential part G of the UCC factors into the first-order and second-order terms of G in the polynomial. For example, the format of the polynomial in FIG. 1 is as follows:

[0033]

number

[0034] JPEG2025529955000011.jpg19170

[0035] The server 100 determines a wave function for expressing the quantum state of an object corresponding to a UCC quantum circuit to be simulated and N UCC factors for expressing the circuit, based on the UCC quantum circuit to be simulated. The UCC quantum circuit is set for the object.

[0036] When performing quantum simulation on the circuit based on the wave function and UCC factors, the server 100 operates each UCC factor with the wave function in the form of the above polynomial, and finally obtains a result wave function through quantum simulation, which can represent the quantum state of the object after it passes through the UCC quantum circuit.

[0037] The format for computing each UCC factor with the wave function in the form of a polynomial as described above may be as follows:

[0038]

number

[0039] where ψ is the wave function.

[0040] By using polynomial transformation, G is transformed from its exponential part into linear and quadratic terms, which significantly reduces the computational complexity of the wave function and UCC factors in quantum simulation. This enables quantum simulation without decomposing the UCC factors into quantum gates, effectively improving the efficiency of quantum simulation and achieving the effect of quickly and easily determining the quantum state of an object corresponding to a UCC quantum circuit.

[0041] 3 is a flowchart of a quantum circuit simulation method according to an embodiment of the present application, in which the server is described as the computer device. The quantum circuit simulation method includes the following steps:

[0042] In step S301, a polynomial obtained by converting the UCC factors is obtained.

[0043] JPEG2025529955000013.jpg26170

[0044] In an embodiment of the present application, in order to improve the efficiency of quantum simulation and reduce the computational complexity in the simulation, the server may convert the UCC factors to obtain a polynomial, or may directly obtain the polynomial converted from the UCC factors. The polynomial includes a linear term and a quadratic term of G. By converting the UCC factors from exponential form to a polynomial, the computational complexity of multiplying the UCC factors in quantum calculations during subsequent quantum simulation can be significantly reduced, effectively increasing the speed of the quantum simulation.

[0045] Here, quantum computing is a computing method based on quantum logic, and the basic unit for storing data is a Qubit (quantum bit), which is the basic unit of quantum computing.

[0046] A classical computer (such as a PC) includes a host, display, mouse, keyboard, etc., where the host generally includes components such as the mainboard, power supply, chips, video card, and hard disk, and occupies a small mechanical space and can be used in a room-temperature environment. A quantum computer (such as a superconducting quantum computer) mainly includes three parts: a quantum chip, a control system, and a low-temperature system. The quantum chip is used for calculations; the control system generates, collects, controls, and processes the precise signals required by the quantum chip; and the low-temperature system provides the quantum chip with a stable operating environment, including ultra-low temperatures, external electromagnetic shielding, and insulation. Due to their large volume, quantum computers generally require a dedicated space to operate.

[0047] JPEG2025529955000014.jpg36170

[0048] In one possible implementation, the polynomial is specifically as follows:

[0049]

number

[0050] JPEG2025529955000016.jpg16170

[0051] JPEG2025529955000017.jpg33170

[0052] In step S302, a wave function for representing the quantum state of the object is obtained.

[0053] The wave function obtained in step S302 is also called an initial wave function. The initial wave function represents one quantum state of the object and can be determined according to the specific object. For example, if the object is a chemical molecule, it can be a Hartree-Fock state in the chemical field. Its format is simple, and the initial quantum state is generally represented by a vector with only one element being 1, such as [1,0,0,0].

[0054] JPEG2025529955000018.jpg44170

[0055] In step S303, N UCC divisors for constructing a UCC quantum circuit are obtained.

[0056] JPEG2025529955000019.jpg46170

[0057] For different objects or different quantum computing requirements, different UCC quantum circuits, i.e., UCC quantum circuits to be simulated, can be designed. Different UCC quantum circuits mainly differ in the quantity of quantum states, i.e., quantum states with corresponding quantities are designed according to the actual computing object or computing requirements. Through quantum computing of the UCC quantum circuit, the quantum state of the object corresponding to the UCC quantum circuit after the quantum computing can be determined.

[0058] As described above, a UCC quantum circuit can be considered to be obtained by multiplying multiple UCC factors, so N>1. The N UCC factors are obtained by the following method, that is, by traversing all the single excitation operators and double excitation operators, specifically, by traversing the single excitation operators and double excitation operators of G below and the subscripts i, j, k, and l in the formula, resulting in a total of N 4 On the other hand, wave functions are used to represent the quantum state of an object simulated by a UCC quantum circuit, specifically, the probability that the quantum state of the object will appear in a particular time and space.

[0059] In one possible implementation, if the object is a chemical molecule, G can be expressed in the following form:

[0060] JPEG2025529955000020.jpg19170

[0061] JPEG2025529955000021.jpg29170

[0062] JPEG2025529955000022.jpg61170

[0063] The single-excitation or double-excitation forms of G can be used to symmetrically adjust the quantum states of chemical molecules and improve the quantum computing accuracy of UCC quantum circuits.

[0064] JPEG2025529955000023.jpg24170

[0065] In step S304, a quantum simulation is performed on the UCC quantum circuit based on the wave function and the N UCC factors to obtain a resultant wave function, and the quantum simulation is used to calculate each UCC factor with the wave function in the form of the polynomial.

[0066] As described above, in polynomial form, the operator G is transformed from the exponential part where the UCC factors originally reside into linear and quadratic terms of a polynomial. In operations based on polynomials and wave functions, the number of matrix multiplications to be performed is reduced to a constant order, i.e., two. In one possible implementation, the step of computing each UCC factor with the wave function in the form of a polynomial is performed as follows:

[0067]

number

[0068] where ψ is the wave function.

[0069] JPEG2025529955000025.jpg28170

[0070]

number

[0071] JPEG2025529955000027.jpg14170

[0072] By continuing to operate the wave function corresponding to the i+1th UCC factor with the i+1th UCC factor, and by analogy, after the operation of the wave function corresponding to the Nth UCC factor with the last (i.e., Nth) UCC factor is completed, the resulting wave function is referred to as a result wave function, and the result wave function can be used to represent the quantum simulation result for the UCC quantum circuit.

[0073] Thus, in one possible implementation, the quantum simulation is performed as follows:

[0074]

number

[0075] JPEG2025529955000029.jpg23170

[0076] More specifically, it can be expressed as follows:

[0077]

number

[0078] JPEG2025529955000031.jpg39170

[0079] Highly efficient quantum simulation allows for the rapid determination of optimal parameters θ for the UCC quantum circuit based on quantum simulation. i The parameter θ can be adjusted. i may represent the i-th UCC factor parameter value, which may have different parameter values ​​for different UCC factors, or may have the same parameter value for all or some of the UCC factors.

[0080] As can be seen, to reduce the computational complexity of quantum simulation, a polynomial is obtained by converting the UCC factors in exponential form, and the anti-Hermitian excitation operator G in the exponential part of the UCC factors can be converted into linear and quadratic terms of G in the polynomial through this conversion. Based on the UCC quantum circuit to be simulated, a wave function representing the quantum state of an object corresponding to the circuit and N UCC factors representing the circuit are determined. When performing quantum simulation on the circuit based on the wave function and UCC factors, each UCC factor is operated with the wave function in the above polynomial format to finally obtain a resultant wave function through quantum simulation. By converting the UCC factors from exponential form into linear and quadratic terms of G through polynomial conversion, the computational complexity of the wave function and UCC factors in quantum simulation is significantly reduced. This eliminates the need to decompose the UCC factors into quantum gates for quantum simulation, effectively improving the efficiency of quantum simulation and achieving the effect of quickly and easily determining the quantum state of an object corresponding to a UCC quantum circuit.

[0081] The objects corresponding to UCC quantum circuits may relate to different fields, such as the fields of physics and chemistry, and the embodiments of the present application are not limited thereto.

[0082] JPEG2025529955000032.jpg40170

[0083] The molecular energy of the chemical molecule can be obtained based on the different quantum states represented by the resulting wave functions, and other chemical properties of the chemical molecule can be calculated based on this. Therefore, the embodiments of the present application can be effectively applied to quantum simulation in the chemical field, thereby improving the efficiency and practicality of quantum simulation in the chemical field.

[0084] When the object corresponding to the above-mentioned UCC quantum circuit is a chemical molecule, the embodiment of the present application provides a method for expressing the wave function in configuration space, which significantly reduces the storage burden of the wave function on the server.

[0085] If the object is a chemical molecule, the wave function is determined by the following method: In step S11, a molecular orbital corresponding to the chemical molecule and a positional combination of positions that the electrons of the molecule can occupy in the molecular orbital are determined, and in step S11, the wave function expressed in configuration space is generated based on the molecular orbital and the positional combination.

[0086] First, the quantum theory knowledge related to this embodiment will be described.

[0087] Molecular orbital: A tool for describing the electronic states in molecular systems, i.e., the electron wave function, which refers to a spatial orbital unless otherwise specified.

[0088] Spatial orbitals and spin orbitals: A concept in chemical molecular orbitals. A single spatial orbital can accommodate two electrons with opposite spin directions. If a single spatial orbital is artificially divided into two orbitals, each of which can accommodate one electron, these orbitals are called spin orbitals.

[0089] JPEG2025529955000033.jpg22170

[0090] Configuration space: describes the space in which the ground states of a chemical quantum system reside, and is smaller than the total qubit space. This is because, due to electron invariance in chemical quantum systems, some total qubit space ground states cannot occur in chemical systems and can be ignored.

[0091] JPEG2025529955000034.jpg49170

[0092] JPEG2025529955000035.jpg61170

[0093] The reason why the number of quantum states to be stored can be significantly reduced is as follows: due to the electron invariance in chemical quantum systems, some ground states in the total quantum bit space cannot appear in chemical systems and can be ignored, so in quantum simulations in the chemical field, the possible configurations of chemical molecules can be determined by the fillable configurations of the electrons of the chemical molecules in the molecular orbitals corresponding to the UCC quantum circuit, and thus the wave function for describing the fillable configurations of the electrons of the chemical molecules in the molecular orbitals is converted from the total quantum bit space to the configuration space and expressed.

[0094] By increasing the speed of UCC circuit simulation, embodiments of the present application can significantly accelerate the design and testing of quantum computational chemistry algorithms in academia and industry, facilitating the practical application of quantum computers and quantum algorithms.

[0095] Figure 5 shows the molecular orbitals of a hydrogen molecule. Fundamental to understanding molecular systems is molecular orbital theory. Molecular orbitals are generated from atomic orbitals, and each orbital can accommodate two electrons with opposite spin orientations. Electrons fill each orbital in order from low energy to high energy.

[0096] A hydrogen molecule has two molecular orbitals, the first molecular orbital numbered 1 and 3, and the second molecular orbital numbered 0 and 2, each number referring to one spin orbital. The ground state of a hydrogen molecule contains one spin-up electron and one spin-down electron, with the spin-up electron potentially occupying positions 0 and 1, and the spin-down electron potentially occupying positions 3 and 2. In this limit, all possible electron occupancies, or all possible configurations, are as shown in Figure 5, which shows four possible forms of configuration space.

[0097] Therefore, the state of a hydrogen molecule can be accurately described in a four-dimensional configuration space. In quantum computing, one qubit generally represents one spin orbit, so the dimensional size of the total qubit space is 16. In fact, this 16-dimensional vector has only four non-zero elements, and all the other elements are zero.

[0098] These four elements, namely the 0101, 1001, 0110, and 1010 elements corresponding respectively to the configuration space (represented by the ground state combinations and shown respectively from left to right in FIG. 5), are non-zero.

[0099] As can be seen, expressing the wave function in configuration space can effectively free up a large amount of storage space compared to related techniques that express the wave function in the entire qubit space. For example, in the above example, when expressing the wave function in the entire qubit space, the server needs to store a 16-dimensional vector, but when expressing the wave function in configuration space, the server only needs to store a 4-dimensional vector.

[0100] Next, the improvement of the anti-Hermitian excitation operator G in the embodiment of the present application will be explained.

[0101] Since quantum states are represented in configuration space, various operators such as G must also be represented in configuration space, thereby improving the efficiency of quantum computation in quantum simulation. G has a simple matrix representation in the entire qubit space, but is represented as a complex sparse matrix in configuration space. If G cannot be stored efficiently and if the multiplication operation of the first-order or second-order terms of G and the wave function cannot be realized, such as Gψ, then expressing the quantum state in configuration space will not improve efficiency.

[0102] In one possible implementation, operating each UCC factor with the wave function in the form of the polynomial in step S303 includes the following steps:

[0103] In step S3031, a first calculation result determination method for calculating the first-order term of G in the polynomial and the wave function, and a second calculation result determination method for calculating the second-order term of G and the wave function are determined.

[0104] In step S3032, the calculation results of each UCC factor and the wave function are obtained according to the first calculation result determination method and the second calculation result determination method.

[0105] The first and second operation result determination methods represent how to obtain corresponding operation results. The first operation result determination method can be determined by a rule in the operation process between the first-order term of G and the wave function, and the second operation result determination method can be determined by a rule in the operation process between the second-order term of G and the wave function. Such a rule may be a conversion rule between the operation result and the wave function, or a conversion rule between an operation intermediate result and the wave function.

[0106] JPEG2025529955000036.jpg71170

[0107] In one possible implementation, the first calculation result determination method includes one rearrangement of the vector characteristics of the wave function and one phase transformation of the wave function, and the second calculation result determination method includes one phase transformation of the wave function.

[0108] When the server performs an operation on the UCC factors and the wave function, the result is the wave function corresponding to the next UCC factor, or the result wave function. Meanwhile, the wave function mainly records the quantum state of the object corresponding to the UCC quantum circuit. The quantum state of any one qubit can be represented by the possible basis states and the coefficients of the basis states.

[0109] Therefore, the rule of change of the ground state and ground state coefficients (e.g., α, β, or the modular square of α, β in the quantum state definition) of each quantum bit described by the wave function before and after each operation can be determined according to the change situation of the quantum state in the wave function after each operation. In an embodiment of the present application, the rule of change of the ground state of each quantum bit described by the wave function is recorded by rearranging the vector features, and the rule of change of the ground state coefficients of each quantum bit described by the wave function is recorded by phase transformation.

[0110] Because the creation or annihilation of particles guided by any G occurs in pairs, the vector feature sorting mainly represents the sorting rule of the basis state coefficients of each quantum bit in the wave function under the influence of the operation of a specific G after calculating the wave function and the corresponding UCC factors. Because the basis state coefficients may change regularly with the guidance of G, the phase transformation mainly represents the sorting rule of the basis state coefficients of each quantum bit in the wave function under the influence of the operation of a specific G after calculating the wave function and the corresponding UCC factors.

[0111] The server records the rearrangement and phase transformation of the vector features related to these G and wave functions, and performs classification and maintenance by operating with the first-order terms of G and the second-order terms of G. Therefore, the server does not need to store G in the form of a configuration space, and by directly storing the rearrangement and phase transformation of the vector features related to G and wave functions, it can realize guidance on the calculation results between UCC factors and wave functions, which significantly improves the calculation efficiency of this part of the quantum simulation.

[0112] To clearly explain the vector feature rearrangements and phase transformations associated with G and the wave function, we now provide a specific illustrative example where G is in the form of a single excitation.

[0113] In one possible implementation, when G is a single excitation type, in the first calculation result determination method, the phase parameter adopted for phase transformation is any one of -1, 0, and 1, and in the second calculation result determination method, the phase parameter adopted for phase transformation is any one of -1 and 0.

[0114] As an example, assume that the singly excited form of the operator G is:

[0115]

number

[0116] We now explain how to realize Gψ in configuration space, where i≠j. The realization of the double excitation operator is similar and will not be repeated here.

[0117] JPEG2025529955000038.jpg42170

[0118] When the operator G is in the single excited form above, the ground states in the configuration space can be divided into four types (as shown in the table below). After G acts on these states, different effects are obtained.

[0119] [Table 2]

[0120] According to the above rules, the realization of Gψ can be divided into two steps.

[0121] In step 1, the state where there is no particle at i and there is a particle at j is exchanged with the state where there is a particle at j and there is no particle at i. That is, one rearrangement of the vector features is performed on the ψ vector.

[0122] In step 2, each element of the ψ vector is multiplied by a phase parameter based on the cases listed in the table above to achieve the phase transformation. The possible values ​​of the phase parameter are -1, 0, and 1.

[0123] JPEG2025529955000040.jpg10170

[0124]

number

[0125] The ground states in the configuration space can be divided into two types (as shown in the table below). After G acts on these states, different effects are obtained.

[0126] [Table 3]

[0127] JPEG2025529955000043.jpg21170

[0128] JPEG2025529955000044.jpg23170

[0129] After obtaining the latest wave function in the calculation, the server determines the corresponding first calculation result determination method and second calculation result determination method according to the i-th UCC factor corresponding to this calculation. For example, when G of the i-th UCC factor is the above-mentioned single excitation format, the first calculation result determination method is rearrangement for the feature vector and phase multiplication for the phase transformation, and the second calculation result determination method is phase multiplication for the phase transformation.

[0130] JPEG2025529955000045.jpg22170

[0131] JPEG2025529955000046.jpg22170

[0132] Therefore, for the operation between the wave function and the UCC factor, only the matrix addition operation remains, and the server can quickly obtain the final operation result, i.e., a new wave function (e.g., a wave function for operation with the i+1th UCC factor, or a result wave function).

[0133] The quantum simulation solution proposed in the embodiments of the present application can significantly increase the quantum simulation speed of UCC quantum circuits and can be applied to quantum simulation of larger-scale UCC quantum circuits.

[0134] The table below shows the realistic simulation times for hydrogen chain systems using unitary coupled cluster singles and doubles (UCCSD) in the STO-3G basis group. The software compared includes the present quantum simulation solution and several related quantum simulation technologies, such as Qiskit-Nature, PennyLane, Tequila, and MindQuantum. While the computational speeds of related technologies other than the present solution are roughly comparable, MindQuantum is relatively faster. Meanwhile, the present quantum simulation solution is more than 1,000 times faster than MindQuantum for H8 and H10 systems. Meanwhile, while other related technologies can generally simulate systems with a maximum of 20 qubits, the present quantum simulation solution can perform quantum simulation of a large quantum system with 32 qubits within a reasonable time frame, a task that has not been achieved by any related technologies to date.

[0135] [Table 4]

[0136] Figure 7 shows the potential energy surface used for another application example of the present invention, i.e., a hydrogen molecule. The large basis set of cc-pVTZ is used, and the system size is 56 qubits. The results calculated by the quantum simulation in the present invention are in very good agreement with the exact solution. As can be seen from the table above, other related technologies cannot simulate such a large system at all. Nevertheless, because this system has a small number of electrons and a correspondingly small number of configurations, quantum simulation can be performed efficiently using the present invention. As can be seen, the quantum simulation realized by the embodiment of the present application produces calculation results that are highly consistent with the exact solution. The calculation results corresponding to the embodiment of the present application are UCCSD (TenCirChem), and the exact solution is FCI (exact).

[0137] The English meanings in Figure 7 are as follows: Energy: Molecular energy. Hartree: A unit of energy. Error: Error. Bond length: The bond length, indicated by an A with a circle above it, in units of bond length, 100 pm, or angstrom. Hartree-Fock: Approximate solution to classical calculations of molecular energies. FCI (exact): Exact solution for classical calculation of molecular energies. IBM Nature 2017: IBM quantum computing results published in Nature in 2017, https: / / www.nature.com / articles / nature23879. UCCSD (TenCirChem): Molecular energies obtained by classical simulations according to the present example. UCCSD Error: The error in the molecular energy obtained by the classical simulation according to the present embodiment.

[0138] Based on the embodiments corresponding to the above-mentioned FIGS. 1 to 7, FIG. 8 is a configuration diagram of a quantum circuit simulation device according to an embodiment of the present application, where the quantum circuit simulation device 800 includes an acquisition unit 801, a determination unit 802, and a simulation unit 803.

[0139] The obtaining unit 801 is configured to obtain a polynomial obtained by transforming a UCC factor, where the exponent part of the UCC factor includes an anti-Hermitian excitation operator G, and the polynomial includes a first-order term and a second-order term of G; The determining unit 802 is configured to obtain N UCC factors corresponding to a UCC quantum circuit to be simulated, and obtain a wave function, wherein the wave function is used to represent a quantum state of an object corresponding to the UCC quantum circuit, where N>1; The simulation unit 803 is configured to perform a quantum simulation on the UCC quantum circuit based on the wave function and the N UCC factors to obtain a result wave function, wherein the quantum simulation is used to operate each UCC factor with the wave function in the form of the polynomial, and the result wave function is used to represent the quantum state of the object simulated by the UCC quantum circuit.

[0140] In one possible implementation, the polynomial is specifically as follows:

[0141]

number

[0142] JPEG2025529955000049.jpg14170

[0143] The step of computing each UCC factor with the wave function in the form of a polynomial is performed using the following equation:

[0144]

number

[0145] where ψ is the wave function.

[0146] In one possible implementation, when the objects are chemical molecules, G comprises the following representation:

[0147] JPEG2025529955000051.jpg21170

[0148] JPEG2025529955000052.jpg18170

[0149] In one possible implementation, the determination unit is further configured to, when the object is a chemical molecule, determine a molecular orbital corresponding to the chemical molecule and a positional combination of positions that electrons of the molecule can occupy in the molecular orbital, and generate the wave function expressed in a configuration space based on the molecular orbital and the positional combination.

[0150] In one possible implementation, the simulation unit further comprises:

[0151] The system is configured to determine a first operation result determination method for calculating a first-order term of G in the polynomial and the wave function, and a second operation result determination method for calculating a second-order term of G and the wave function, and to obtain an operation result between each UCC factor and the wave function based on the first operation result determination method and the second operation result determination method.

[0152] In one possible implementation, the first calculation result determination method includes one rearrangement of the vector characteristics of the wave function and one phase transformation of the wave function, and the second calculation result determination method includes one phase transformation of the wave function.

[0153] In one possible implementation, when G is a single excitation type, in the first calculation result determination method, the phase parameter adopted for phase transformation is any one of -1, 0, and 1, and in the second calculation result determination method, the phase parameter adopted for phase transformation is any one of -1 and 0.

[0154] In one possible implementation, the quantum simulation is performed using the following equation:

[0155]

number

[0156] JPEG2025529955000054.jpg24170

[0157] In one possible implementation, the determination unit is further configured to, when the object is a chemical molecule, determine a molecular energy of the chemical molecule based on the quantum state of electrons in the chemical molecule represented by the resultant wave function.

[0158] As can be seen, to reduce the computational complexity of quantum simulation, a polynomial is obtained by transforming the UCC factors in exponential form, and the anti-Hermitian excitation operator G in the exponential part of the UCC factors can be transformed into linear and quadratic terms of G in the polynomial through this transformation. Based on the UCC quantum circuit to be simulated, a wave function representing an object quantum state corresponding to the circuit and N UCC factors representing the circuit are determined. When performing quantum simulation on the circuit based on the wave function and UCC factors, each UCC factor is operated with the wave function in the form of the polynomial to finally obtain a resultant wave function through quantum simulation. By transforming G from its exponential part into linear and quadratic terms through the polynomial transformation, the computational complexity of the wave function and UCC factors in quantum simulation is significantly reduced. This eliminates the need to decompose the UCC factors into quantum gates for quantum simulation, effectively improving the efficiency of quantum simulation and achieving the effect of quickly and easily determining the quantum state of an object corresponding to a UCC quantum circuit.

[0159] An embodiment of the present application further provides a computer device, which may be the computer device described above and may include a terminal device or a server, and the quantum circuit simulation device described above may be disposed on the computer device. The computer device will be described below with reference to the drawings.

[0160] If the computer device is a terminal device, refer to FIG. 9, the embodiment of the present application provides a terminal device, and takes the case where the terminal device is a mobile phone as an example.

[0161] 9 is a block diagram showing a configuration of a portion of a mobile phone related to a terminal device provided in an embodiment of the present application. Referring to FIG. 9, the mobile phone includes components such as a radio frequency (RF) circuit 1410, a memory 1420, an input unit 1430, a display unit 1440, a sensor 1450, an audio circuit 1460, a wireless fidelity (WiFi) module 1470, a processor 1480, and a power supply 1490. Those skilled in the art will understand that the configuration of the mobile phone shown in FIG. 9 is not intended to limit the mobile phone, and that the mobile phone may include more or fewer components than those shown, may combine some components, or may have a different component arrangement.

[0162] Each component of the mobile phone will be specifically described below with reference to FIG.

[0163] The RF circuitry 1410 may be configured to receive and transmit signals during transmission and reception of information or during a call, in particular to receive downlink information from a base station and then transmit it to the processor 1480 for processing, and to transmit uplink data to the base station.

[0164] The memory 1420 may be configured to store software programs and modules, and the processor 1480 executes the software programs and modules stored in the memory 1420 to perform various functional applications and data processing of the mobile phone. The memory 1420 may mainly include a program storage area and a data storage area. Here, the program storage area may store an operating system, application programs necessary for at least one function (e.g., audio playback function, image playback function), etc., and the data storage area may store data created depending on the usage of the mobile phone (e.g., audio data, phone book), etc. Furthermore, the memory 1420 may include a high-speed random access memory and may also include at least one non-volatile memory such as a magnetic disk storage device, flash memory, or other volatile solid-state storage device.

[0165] The input unit 1430 may be configured to receive input numeric or character information and generate keyboard signal inputs related to user settings and function control of the mobile phone. Specifically, the input unit 1430 may include a touch panel 1431 and other input devices 1432.

[0166] The display unit 1440 may be configured to display information entered by or provided for the user, as well as various menus of the mobile phone. The display unit 1440 may include a display panel 1441.

[0167] The mobile phone may further include at least one sensor 1450, such as a light sensor, a motion sensor, and other sensors.

[0168] Audio circuitry 1460, speaker 1461, and microphone 1462 may provide an audio interface between the user and the mobile phone.

[0169] WiFi is a short-range wireless transmission technology, and by using the WiFi module 1470, a mobile phone can assist users in receiving and sending emails, browsing web pages, accessing stream media, etc., and enable users wireless broadband Internet access.

[0170] The processor 1480 is the control center of the mobile phone and is connected to various parts of the entire mobile phone through various interfaces and lines, and performs various functions of the mobile phone and performs data processing by executing or executing software programs and / or modules stored in the memory 1420 and by calling up data stored in the memory 1420. The mobile phone further includes a power source 1490 (such as a battery) for powering each component.

[0171] In the embodiment of the present application, the processor 1480 included in the terminal device further has the following functions:

[0172] That is, the method performs the following steps: obtaining a polynomial obtained by transforming a UCC factor, where the exponent part of the UCC factor includes an anti-Hermitian excitation operator G, and the polynomial includes a first-order term and a second-order term of G; obtaining N UCC factors corresponding to a UCC quantum circuit to be simulated; obtaining a wave function, where the wave function is used to represent N quantum states of an object, where N is an integer and N>1; performing a quantum simulation on the UCC quantum circuit based on the wave function and the N UCC factors, and during the quantum simulation, operating each UCC factor with the wave function in the form of the polynomial; and obtaining a resultant wave function by the quantum simulation, where the resultant wave function is used to represent the quantum state of the object simulated by the UCC quantum circuit.

[0173] When the computer device is a server, an embodiment of the present application further provides a server. Referring to FIG. 10, FIG. 10 is a block diagram of a server 1500 according to an embodiment of the present application. The server 1500 may vary significantly in configuration or performance and may include one or more central processing units (CPUs) 1522 (e.g., one or more processors), memory 1532, and one or more storage media 1530 (e.g., one or more mass storage devices) that store application programs 1542 or data 1544. Here, the memory 1532 and the storage media 1530 may be temporary or permanent storage. The program stored in the storage media 1530 may include one or more modules (not shown), each of which may include a series of instruction operations for the server. Furthermore, the central processing unit 1522 may be configured to communicate with the storage medium 1530 and execute the series of instruction operations in the storage medium 1530 on the server 1500.

[0174] Server 1500 may further include one or more power sources 1526, one or more wired or wireless network interfaces 1550, one or more input / output interfaces 1558, and / or one or more operating systems 1541, such as Windows® Server™, Mac OS X™, Unix®, Linux®, FreeBSD™, etc.

[0175] The steps performed by the server in the above embodiment may be based on the server configuration shown in FIG.

[0176] An embodiment of the present application further provides a storage medium containing a computer program, the computer program performing the method provided in the above embodiment.

[0177] An embodiment of the present application further provides a computer program product including instructions, which when executed on a computer, cause the computer to perform the method described above.

[0178] Those skilled in the art can understand that all or part of the steps for realizing the above embodiments can be performed by hardware associated with program instructions, and the above programs may be stored in a computer-readable storage medium, which, when executed, performs the steps comprising the above method embodiments, and the above storage medium may be at least one of various media capable of storing program code, such as a read-only memory (ROM), a magnetic disk, or an optical disk.

[0179] It should be noted that the embodiments in this specification are described step by step, and the same or similar parts between the embodiments can be referred to, with each embodiment focusing on the differences from other embodiments. In particular, the device and system embodiments are essentially similar to the method embodiments, so they can be briefly described, and relevant parts can be referred to in part of the description of the method embodiments. The device and system embodiments described above are merely illustrative, and units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, located in one place, or distributed across multiple network units. Depending on actual needs, some or all of the parts therein can be selected to achieve the objectives of the technical solutions in this embodiment. Those skilled in the art can understand and implement them without any creative effort.

[0180] The above content is merely a specific embodiment of the present application, and the scope of protection of the present application is not limited thereto. Any modifications or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Furthermore, the present application can also be further combined to provide more implementations based on the implementations provided in each of the above aspects. Therefore, the scope of protection of the present application shall be subject to the scope of protection of the claims.

Claims

1. 1. A quantum circuit simulation method executed by a computing device, comprising: obtaining a polynomial obtained by transforming a Unitary Combination Class (UCC) factor, the exponent of which contains an anti-Hermitian excitation operator G, and the polynomial contains first-order and second-order terms of G; obtaining N UCC factors for constructing a UCC quantum circuit, where N is an integer and N>1; obtaining a wave function, said wave function being used to represent a quantum state of an object; performing a quantum simulation on the UCC quantum circuit based on the wave function and the N UCC factors to obtain a resultant wave function, wherein the quantum simulation is used to operate each UCC factor with the wave function in the form of a polynomial, and the resultant wave function is used to represent the quantum state of the object simulated by the UCC quantum circuit.

2.

3.

4. If the object is a chemical molecule, the wave function is determining molecular orbitals corresponding to the chemical molecule and positional combinations of positions that electrons of the molecule can occupy in the molecular orbitals; generating the wave function expressed in configuration space based on the molecular orbitals and the position combinations; The quantum circuit simulation method according to any one of claims 1 to 3.

5. said step of computing each UCC factor with said wave function in the form of a polynomial, determining a first calculation result determination method for calculating a first-order term of G in the polynomial and the wave function, and a second calculation result determination method for calculating a second-order term of G and the wave function; obtaining a calculation result between each UCC factor and the wave function based on the first calculation result determination method and the second calculation result determination method, The quantum circuit simulation method according to any one of claims 1 to 4.

6. the first calculation result determination method includes one rearrangement of vector features of the wave function and one phase transformation of the wave function, and the second calculation result determination method includes one phase transformation of the wave function; The quantum circuit simulation method according to claim 5 .

7. When G is a single excitation type, in the first calculation result determination method, a phase parameter adopted for phase conversion is any one of −1, 0, and 1, and in the second calculation result determination method, a phase parameter adopted for phase conversion is any one of −1 and 0. The quantum circuit simulation method according to claim 6.

8.

9. When the object is a chemical molecule, the quantum circuit simulation method includes: determining a molecular energy of the chemical molecule based on the quantum state of electrons in the chemical molecule represented by the resulting wave function; The quantum circuit simulation method according to any one of claims 1 to 7.

10. A quantum circuit simulation device, An obtaining unit, a determining unit, and a simulation unit, The obtaining unit is configured to obtain a polynomial obtained by transforming a unitary coupling class (UCC) factor, wherein an exponent part of the UCC factor includes an anti-Hermitian excitation operator G, and the polynomial includes a first-order term and a second-order term of G; The determination unit is configured to obtain N UCC factors for constructing a UCC quantum circuit and obtain a wave function, where N is an integer and N>1, and the wave function is used to represent a quantum state of an object corresponding to the UCC quantum circuit; The simulation unit is configured to perform a quantum simulation on the UCC quantum circuit based on the wave function and the N UCC factors to obtain a resultant wave function, the quantum simulation being used to operate each UCC factor with the wave function in the form of a polynomial, and the resultant wave function being used to represent the quantum state of the object simulated by the UCC quantum circuit.

11. the determining unit is further configured to, when the object is a chemical molecule, determine a molecular orbital corresponding to the chemical molecule and a positional combination of positions that an electron of the molecule can occupy in the molecular orbital, and generate the wave function expressed in a configuration space based on the molecular orbital and the positional combination. The quantum circuit simulation device according to claim 10.

12. The simulation unit further comprises: determining a first calculation result determination method for calculating the first-order term of G in the polynomial and the wave function, and a second calculation result determination method for calculating the second-order term of G and the wave function; The method is configured to obtain a calculation result between each UCC factor and the wave function based on the first calculation result determination method and the second calculation result determination method. The quantum circuit simulation device according to claim 10 or 11.

13. A computer device comprising: A processor and a memory, the memory is configured to store program code and to transmit the program code to the processor; A computing device, wherein the processor is configured to carry out the method of any one of claims 1 to 9 according to instructions in the program code.

14. A computer storage medium having stored thereon a computer program for carrying out the method according to any one of claims 1 to 9.

15. A computer program product comprising instructions which, when executed on a computer, cause said computer to carry out the method of any one of claims 1 to 9.

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