Method and device for determining chemical energy of target substance and medium

Abstract

The invention discloses a method and device for determining chemical energy of a target substance and a medium, and the method comprises the steps: firstly converting a cluster operator in a Fermi form into a cluster operator in a Fouli operator form, and then determining a target cluster operator used for constructing a quantum circuit from the cluster operator in the Fouli operator form, the method comprises the following steps: constructing a quantum circuit according to a target cluster operator, operating the quantum circuit to obtain a measurement result of the quantum circuit, and finally determining the chemical energy of a target substance according to the measurement result of the quantum circuit. And further development of quantum chemistry simulation application is promoted.

Description

Technical Field

[0001] The present invention belongs to the field of quantum computing technology, and in particular to a method, device and medium for determining the chemical energy of a target substance. Background Art

[0002] Quantum computers are physical devices that follow the laws of quantum mechanics to perform high-speed mathematical and logical operations, store and process quantum information. When a device processes and calculates quantum information and runs quantum algorithms, it is a quantum computer. Quantum computers have become a key technology under research because they have the ability to process mathematical problems more efficiently than ordinary computers. For example, they can speed up the time to crack RSA keys from hundreds of years to a few hours.

[0003] Quantum computing simulation is a simulation that uses numerical calculations and computer science to simulate calculations that follow the laws of quantum mechanics. As a simulation program, it uses the basic laws of quantum bits in quantum mechanics and the high-speed computing power of computers to characterize the spatiotemporal evolution of quantum states.

[0004] With the continuous improvement of quantum chemistry theory, computational chemistry has become an important tool for chemists to explain experimental phenomena, predict experimental results, and guide experimental design. It has been widely used in drug synthesis, catalyst preparation, etc. However, facing the huge amount of calculation involved in the target substance to be simulated in computational chemistry, traditional classical calculations are difficult to simulate complex target substances, or even if they can be simulated, the calculation time is long and the amount of calculation is large. How to solve the above problems has become an important research topic at present. Summary of the invention

[0005] The purpose of the present invention is to provide a method, device and medium for calculating the energy of a target substance to address the deficiencies in the prior art, thereby improving the calculation speed of solving the target substance by predetermining the cluster operator excitation term and the number of excitation terms in the form of the Pauli operator of the target substance, and promoting the further development of quantum chemical simulation applications.

[0006] An embodiment of the present application provides a method for calculating the energy of a target substance, wherein the ground state wave function of the target substance is determined according to a unitary operator and a Hartree Fock state, and the unitary operator is determined according to a cluster operator; the method comprises:

[0007] converting the cluster operator in fermion form into the cluster operator in Pauli operator form;

[0008] Determining target cluster operators for constructing quantum circuits from the cluster operators in the Pauli operator form, wherein the number of the target cluster operators is less than the number of the cluster operators in the Pauli operator form;

[0009] Constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit, wherein the initial state of the quantum circuit is the Hartree Fock state;

[0010] The chemical energy of the target substance is determined according to the measurement result of the quantum circuit.

[0011] Optionally, the Hartree Fock state of the target substance is determined based on electronic information and electron spin orbit information of the target substance.

[0012] Optionally, converting the cluster operator in the form of a fermion into the cluster operator in the form of a Pauli operator comprises:

[0013] A mapping method is selected to transform the cluster operator of the target substance in the form of fermions into the cluster operator in the form of Pauli operators; wherein the mapping method includes one of Jordan-Wigner transformation, Parity transformation and Bravyi-Kitaev transformation.

[0014] Optionally, constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit includes:

[0015] Constructing a quantum circuit corresponding to the target cluster operator excitation term and the number of excitation terms, the quantum circuit is used to evolve the quantum bit from the Hartree Fock state to the target state described by the ground state wave function of the target substance, and taking the target state as the measurement result of the quantum circuit; wherein the ground state wave function |Ψ(θ)> satisfies θ is the optimal variational parameter, T is the cluster operator, is a unitary operator, |ψ> HF is the Hartree Fock state of the target substance.

[0016] Optionally, before constructing the target cluster operator excitation terms and the quantum circuit corresponding to the number of excitation terms, the method further includes:

[0017] A group of quantum bits is obtained, wherein the number of the quantum bits is determined according to the target cluster operator excitation term in the form of the target substance Pauli operator and the number of excitation terms, wherein the initial state of the quantum bit is |0>;

[0018] A first quantum functional module is constructed to evolve the initial state into the Hartree Fock state.

[0019] Optionally, constructing the target cluster operator excitation term and the quantum circuit corresponding to the number of excitation terms includes:

[0020] Based on the first quantum function module, a second quantum function module is constructed to evolve the Hartree Fock state into a ground state wave function of the target substance, so as to generate the target cluster operator excitation term and a quantum circuit corresponding to the number of excitation terms.

[0021] Optionally, determining the chemical energy of the target substance according to the measurement result of the quantum circuit includes:

[0022] According to the ground state wave function and the optimal variational parameter, the energy of the target substance is calculated by the following formula:

[0023] f=<Ψ(θ)|H|Ψ(θ)>

[0024] Wherein, E is the energy of the target substance, and H is the Hamiltonian of the target substance.

[0025] Another embodiment of the present application provides a device for calculating target material energy, the device comprising:

[0026] A conversion module, used for converting the cluster operator in the form of fermion into the cluster operator in the form of Pauli operator;

[0027] A first determination module is used to determine target cluster operators for constructing quantum circuits from the cluster operators in the Pauli operator form, wherein the number of the target cluster operators is less than the number of the cluster operators in the Pauli operator form;

[0028] An acquisition module, used for constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit, wherein the initial state of the quantum circuit is the Hartree Fock state;

[0029] The second determination module is used to determine the chemical energy of the target substance according to the measurement result of the quantum circuit.

[0030] Optionally, the conversion module includes:

[0031] A mapping unit is used to select a mapping method to transform the cluster operator of the target substance in the form of fermions into the cluster operator in the form of Pauli operators; wherein the mapping method includes one of Jordan-Wigner transformation, Parity transformation and Bravyi-Kitaev transformation.

[0032] Optionally, obtain modules including:

[0033] A construction unit is used to construct the target cluster operator excitation term and a quantum circuit corresponding to the number of excitation terms, wherein the quantum circuit is used to evolve the quantum bit from the Hartree Fock state to the target state described by the ground state wave function of the target substance, and the target state is used as the measurement result of the quantum circuit; wherein the ground state wave function |Ψ(θ)> satisfies θ is the optimal variational parameter, T is the cluster operator, is a unitary operator, |ψ> HF is the Hartree Fock state of the target substance.

[0034] Optionally, before the construction unit, the device further includes:

[0035] An obtaining unit, used for obtaining a group of quantum bits, wherein the number of the quantum bits is determined according to the target cluster operator excitation term in the form of the target substance Pauli operator and the number of excitation terms, wherein the initial state of the quantum bit is |0>;

[0036] A construction unit is used to construct a first quantum functional module that evolves the initial state into the Hartree Fock state.

[0037] Optionally, the construction unit includes:

[0038] A construction subunit is used to construct, based on the first quantum function module, a second quantum function module that evolves the Hartree Fock state into a ground state wave function of the target substance, so as to generate the target cluster operator excitation term and a quantum circuit corresponding to the number of excitation terms.

[0039] Optionally, the second determining module includes:

[0040] A calculation unit is used to calculate the energy of the target substance according to the ground state wave function and the optimal variational parameter by the following formula:

[0041] E=<Ψ(θ)|G|Ψ(θ)>

[0042] Wherein, E is the energy of the target substance, and H is the Hamiltonian of the target substance.

[0043] An embodiment of the present application provides a storage medium, in which a computer program is stored, wherein the computer program is configured to execute any of the above methods when running.

[0044] An embodiment of the present application provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute any one of the methods described above.

[0045] Compared with the prior art, the present invention first converts a cluster operator in the form of a fermion into a cluster operator in the form of a Pauli operator, then determines a target cluster operator for constructing a quantum circuit from the cluster operator in the form of a Pauli operator, constructs a quantum circuit according to the target cluster operator and runs the quantum circuit to obtain a measurement result of the quantum circuit, and finally determines the chemical energy of the target substance according to the measurement result of the quantum circuit. By predetermining the cluster operator excitation term and the number of excitation terms in the form of a Pauli operator of the target substance, the present invention improves the calculation speed of solving the target substance and promotes the further development of quantum chemical simulation applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a system network block diagram of a method for calculating target material energy provided by an embodiment of the present invention;

[0047] Figure 2 It is a flow chart of a method for calculating target material energy provided by an embodiment of the present invention;

[0048] Figure 3 It is a schematic diagram of the structure of a target material energy calculation device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but should not be construed as limiting the present invention.

[0050] The embodiment of the present invention first provides a method for determining the chemical energy of a target substance. The method can be applied to electronic devices, such as computer terminals, specifically ordinary computers, quantum computers, etc.

[0051] The following describes it in detail by taking running on a computer terminal as an example. Figure 1 1 is a system network block diagram of a method for determining the chemical energy of a target substance provided by an embodiment of the present invention. The system applied to the method for determining the chemical energy of a target substance may include a network 110, a server 120, a wireless device 130, a client 140, a storage unit 150, a classical processing system 160, a quantum processing system 170, and may also include additional memories, classical processors, quantum processors, and other devices not shown.

[0052] The network 110 is a medium that provides a communication link between various devices and computers connected together within a system network for the method of determining the chemical energy of a target substance, including but not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof. The connection method may be a wired or wireless communication link or an optical fiber cable.

[0053] The server 120 and the client 140 are conventional data processing systems that may contain data and applications or software tools that perform conventional computing processes. The client 140 may be a personal computer or a network computer, so the data may also be provided by the server 120. The wireless device 130 may be a smart phone, a tablet, a laptop, a smart wearable device, etc. The storage unit 150 may include a database 151, which may be configured to store data such as quantum bit parameters, quantum logic gate parameters, quantum circuits, quantum programs, etc.

[0054] The classical processing system 160 (quantum processing system 170) may include a classical processor 161 (quantum processor 171) for processing classical data (quantum data) and a memory 163 (memory 172) for storing classical data (quantum data). The classical data (quantum data) may be a boot file, an operating system image, and an application 162 (application 173). The application 162 (application 173) may be used to implement a quantum algorithm compiled according to a method for determining the chemical energy of a target substance provided in an embodiment of the present invention.

[0055] Any data or information stored or generated in the classical processing system 160 (quantum processing system 170) can also be configured to be stored or generated in another classical (quantum) processing system in a similar manner, and any application program executed by it can also be configured to be executed in another classical (quantum) processing system in a similar manner.

[0056] It should be noted that a true quantum computer is a hybrid structure, which includes at least Figure 1 There are two major parts in it: the classical processing system 160, which is responsible for performing classical calculations and control; and the quantum processing system 170, which is responsible for running quantum programs and thus realizing quantum calculations.

[0057] The classical processing system 160 and the quantum processing system 170 may be integrated into one device or distributed in two different devices. For example, the first device including the classical processing system 160 runs a classical computer operating system, on which quantum application development tools and services are provided, as well as storage and network services required for quantum applications. Users develop quantum applications through the quantum application development tools and services thereon, and send quantum programs to the second device including the quantum processing system 170 through the network services thereon. The second device runs a quantum computer operating system, parses the code of the quantum program through the quantum computer operating system, and compiles it into instructions that can be recognized and executed by the quantum computer measurement and control system. The quantum processor 170 implements the quantum algorithm corresponding to the quantum program according to the instructions.

[0058] In the classic processing system 160 based on silicon chips, the unit of the classic processor 161 is a CMOS tube. This computing unit is not limited by time and coherence, that is, this computing unit is not limited by the length of use and is available at any time. In addition, in the silicon chip, the number of such computing units is also sufficient. At present, the number of computing units in a classic processor is tens of thousands. The number of computing units is sufficient and the computing logic that can be selected by the CMOS tube is fixed, for example: AND logic. When calculating with the help of CMOS tubes, a large number of CMOS tubes are combined with limited logic functions to achieve the calculation effect.

[0059] Unlike this logic unit in the classical processing system 160, the basic computing unit of the quantum processor 171 in the quantum processing system 170 is a quantum bit, and the input of the quantum bit is limited by coherence and coherence time, that is, the quantum bit is limited by the use time and is not available at any time. Making full use of the quantum bit within the available use time of the quantum bit is a key problem in quantum computing. In addition, the number of quantum bits in a quantum computer is one of the representative indicators of the performance of a quantum computer. Each quantum bit realizes the computing function through the logical function configured on demand. In view of the limited number of quantum bits, the logical functions in the field of quantum computing are diverse, such as: Hadamard gate (Hadamard gate, H gate), Pauli-X gate (X gate), Pauli-Y gate (Y gate) Pauli-Z gate (Z gate), X gate, RY gate, RZ gate, CNOT gate, CR gate, iSWAP gate, Toffoli gate, etc. In quantum computing, it is necessary to use limited quantum bits combined with a variety of logical functions to achieve the computing effect.

[0060] Based on these differences, the design of the role of logical functions in quantum bits (including the design of whether the quantum bits are used or not and the design of the efficiency of each quantum bit) is the key to improving the computing performance of quantum computers, and special designs are required. The above-mentioned design for quantum bits is a technical problem that ordinary computing devices do not need to consider or face. In this application, with the continuous improvement of quantum chemical theory, computational chemistry has become an important tool for chemists to explain experimental phenomena, predict experimental results, and guide experimental design. It has been widely used in the synthesis of drugs and the preparation of catalysts. However, in the face of the huge amount of calculation involved in the target substance to be simulated in computational chemistry, traditional classical calculations are difficult to simulate complex target substances, or even if they can be simulated, the calculation time is long and the amount of calculation is large. How to solve the above problems has become an important research content at present. This application provides a method, device and medium for calculating the energy of a target substance to solve the deficiencies in the prior art, and by predetermining the cluster operator excitation term and the number of excitation terms in the form of the Pauli operator of the target substance, the calculation speed of solving the target substance is improved, and the further development of quantum chemical simulation applications is promoted.

[0061] See also Figure 2 , Figure 2 It is a flow chart of a method for determining the chemical energy of a target substance provided in an embodiment of the present invention.

[0062] This embodiment provides an embodiment of a method for determining the chemical energy of a target substance. The method for determining the chemical energy of a target substance may include:

[0063] S201: Convert the cluster operator in the form of a fermion into the cluster operator in the form of a Pauli operator.

[0064] First, before converting the cluster operator in the form of fermions into the cluster operator in the form of Pauli operators, it is necessary to obtain the ground state wave function of the target substance, and the ground state wave function is determined according to the unitary operator and the Hartree Fock state, where the unitary operator can be determined according to the cluster operator.

[0065] The target substance can be considered as the molecular structure modeling for which the user wants to determine the ground state wave function or simulate the ground state energy, including, for example, the number of electrons that make up the molecule, the type of electrons, and the spin-orbit information of the electrons. Electrons are a kind of elementary particles, generally referring to the number of electrons outside the nucleus of the target substance; the electron spin-orbit information is a mathematical method to describe the probability of finding electrons in a specific space outside the nucleus of the target substance, and indicates the possible position of the electrons in three-dimensional space.

[0066] In quantum computing, the selection of the ground state wave function requires a reference wave function as a basis vector. For example, in quantum chemistry, the Hartree Fock state vector is generally used as a reference wave function to satisfy:

[0067] ψ(θ)=U(θ)|ψ> HF

[0068] Where ψ(θ) represents the wave function corresponding to a set of parameters θ, U(θ) represents the matrix operator corresponding to a set of parameters θ, and the reference wave function |ψ> HF Corresponding to the Hartree Fock state in chemistry, it means that the electrons of the molecule are all in the lowest orbital.

[0069] In an optional implementation, the Hartree Fock state of the target substance may be determined based on the electronic information and the electron spin orbit information of the target substance.

[0070] For example, if the target substance is a hydrogen molecule, it contains four single-electron spin molecular orbitals and two electrons. According to the number of electrons in the hydrogen molecule and the electron spin orbital information, if a quantum bit represents an electron spin orbital, that is, 0 represents an empty orbital and 1 represents an occupied orbital, the Hartree Fock state of the hydrogen molecule target substance can be represented by the quantum state |0101> or |0011>.

[0071] Specifically, converting the cluster operator in the form of a fermion into the cluster operator in the form of a Pauli operator may include:

[0072] A mapping method is selected to transform the cluster operator of the target substance in the form of fermions into the cluster operator in the form of Pauli operators; wherein the mapping method includes one of Jordan-Wigner transformation, Parity transformation and Bravyi-Kitaev transformation.

[0073] Specifically, the mapping method may be one of Jordan-Wigner transformation, Parity transformation and Bravyi-Kitaev transformation.

[0074] Those skilled in the art can understand that the mapping principle corresponding to each mapping mode may include: a state mapping principle and an operator mapping principle. For example, for the Jordan-Wigner transformation, the displayed state mapping is:

[0075]

[0076] in, represents the computational state of the quantum bit, represents the transformation matrix, represents the occupied state of the fermion system. The operator mapping shown is:

[0077]

[0078] in, represents the raising and lowering operator, j represents the quantum bit number, P represents the parity set, Z P(j) represents a set of Pauli Z matrices acting on quantum bits belonging to the parity set P, X represents the Pauli X matrix, and Y represents the Pauli Y matrix.

[0079] Equivalently, the operator mapping can also be shown as:

[0080]

[0081]

[0082] in, represents the generation operator, a j represents the annihilation operator, with a j They are collectively called the raising and lowering operators of the fermion system. represents the creation / annihilation operator on the quantum bit, represents the parity operator, and n represents the number of quantum bits.

[0083] The state mapping and operator mapping of other transformations are displayed in the same way as the Jordan-Wigner transformation, so they will not be repeated here.

[0084] The cluster operator can be understood as a type of artificially defined operator used to represent the jumping of electrons in orbits. Suppose that a prepared molecular initial state, such as |ψ> HF The method of evolving to quantum circuits can be simulated by the coupled cluster method (CC), which is a method that starts from the Hartree Fock molecular orbital and obtains the ground state wave function |ψ> through simulation. The simulation here is the exponential coupled cluster operator e T , satisfying: |ψ>=e T |ψ> HF , the T in the assumption is that it is the N electron cluster operator, and its definition is the sum of several excitation operators, that is:

[0085] T=T1+T2+T3+...+T N

[0086] Among them, T1 is the single-particle excitation operator, T2 is the double-particle excitation operator, T3 is the triple-particle excitation operator, and so on for the rest. … To create the operator, a r 、a s is the annihilation operator, p, q, r, s represent orbits, and the unknown coefficient θ pq ,θ pqrs Parameters that need to be found by the optimizer satisfy

[0087] It should be noted that the above-mentioned proposed method may include a single-double-triplet excitation coupling cluster, that is, in the target material, for example, a "truncation" is performed at the triple excitation, and finally only T1, T2 and T3 are left, that is:

[0088]

[0089] in, and To create the operator, a i 、a h and a kis the annihilation operator, a, b, c, i, j, k represent orbits, and the unknown coefficients here are and The variational parameters that can be found by traditional optimizers satisfy

[0090] S202: Determine target cluster operators for constructing quantum circuits from the cluster operators in the Pauli operator form, wherein the number of the target cluster operators is less than the number of the cluster operators in the Pauli operator form.

[0091] It should be noted that after the initial state of the target substance is converted into a cluster operator by means of the pseudo-argumentation method, due to The exponentially coupled cluster operator is not a unitary operator, so it is not possible to directly convert The exponential coupled cluster operator is mapped to the quantum bit by mapping, and the corresponding quantum circuit cannot be constructed. Therefore, it is necessary to construct a unitary operator version of the exponential coupled cluster operator, namely the unitary coupled cluster operator (UCC).

[0092] Among them, the principles proposed by UCC are:

[0093]

[0094] Among them, |Ψ(θ)> is the ground state wave function with parameters, |ψ> HF is the Hartree Fock state, and T is the cluster operator. The cluster operator can be further expressed as:

[0095]

[0096] Among them, T k is the excitation operator. In general, if all electronic excitations are to be considered, the amount of calculation is huge, so single excitation and double excitation are often used to form the UCCSD assumption, that is:

[0097] T=T1+T2

[0098]

[0099]

[0100] in, a is the generation operator and annihilation operator, θ ij ,θ ijkl is the corresponding variational parameter. The generation operator and annihilation operator are Fermi form excitation operators and cannot be directly run on a quantum computer, so the above mapping method is needed to convert the generation operator and annihilation operator into Pauli form operators. For example, for the Jordan-Wigner transformation, the mapping formula can also be:

[0101]

[0102]

[0103] Among them, X, Y, and Z are Pauli operators. After mapping, the single excitation term T1 Pauli form is:

[0104]

[0105] Right now:

[0106]

[0107] The corresponding transpose conjugate operator is:

[0108]

[0109] so:

[0110]

[0111] Similarly, for the double excitation term:

[0112]

[0113] in:

[0114] P_Z=(Z0Z1…Z l-1 )*(Z0Z1…Z k-1 )*(Z0Z1…Z n-1 )*(Z0Z1…Z m-1 )

[0115] P_XY=-Y l X k X n X m -X l Y k X n X m +X l X k Y n X m +X l X k X n Y m

[0116] +X l Y k Y n Y m +Y l X k Y n Y m+Y l Y k X n Y m +Y l Y k Y n X m

[0117] Therefore, UCCSD is proposed to be:

[0118]

[0119] Since these excitation operators are not commutative, we need to use Tóth decomposition to generate quantum circuits:

[0120]

[0121] Among them, P j is the Pauli excitation term. For a single excitation, the Fermi excitation operator generates two Pauli excitation operators after mapping; and for a double excitation, the Fermi excitation operator generates eight Pauli excitation operators after mapping. The functions of these excitation operators are similar, all of which are to transition electrons from some orbits to other orbits, so some Pauli excitation terms can be removed to determine the target cluster operator, thereby reducing the depth of the quantum circuit. For example, for a single excitation, only one of the two Pauli excitation operators can be retained, thereby shortening the quantum circuit to 1 / 2 of the original; for a double excitation, only one of the eight Pauli excitation operators can be retained, thereby shortening the quantum circuit to 1 / 8 of the original.

[0122] S203: constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit, wherein the initial state of the quantum circuit is the Hartree Fock state.

[0123] Specifically, constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit may include:

[0124] Constructing a quantum circuit corresponding to the target cluster operator excitation term and the number of excitation terms, the quantum circuit is used to evolve the quantum bit from the Hartree Fock state to the target state described by the ground state wave function of the target substance, and taking the target state as the measurement result of the quantum circuit; wherein the ground state wave function |Ψ(θ)> satisfies θ is the optimal variational parameter, T is the cluster operator, is a unitary operator, |ψ> HF is the Hartree Fock state of the target substance.

[0125] In an optional implementation, before constructing the target cluster operator excitation term and the quantum circuit corresponding to the number of excitation terms, the method may further include:

[0126] A group of quantum bits is obtained, wherein the number of the quantum bits is determined according to the target cluster operator excitation term in the form of the target substance Pauli operator and the number of excitation terms, wherein the initial state of the quantum bit is |0>; and a first quantum functional module is constructed to evolve the initial state into the Hartree Fock state.

[0127] Exemplarily, the first quantum functional module may include: a Pauli-X gate.

[0128] Specifically, constructing the target cluster operator excitation term and the quantum circuit corresponding to the number of excitation terms may include:

[0129] Based on the first quantum function module, a second quantum function module is constructed to evolve the Hartree Fock state into a ground state wave function of the target substance, so as to generate the target cluster operator excitation term and a quantum circuit corresponding to the number of excitation terms.

[0130] For example, assume that the expression of the target cluster operator excitation term is as follows:

[0131]

[0132] According to the Tóth formula, the quantum circuit corresponding to the target cluster operator excitation term and the number of excitation terms can be constructed by simulating the Hamiltonian term by term, that is, simulating the H1 term first:

[0133]

[0134] Through deduction, it is concluded that the H1 term can be simulated by directly adding an RZ gate to the q0 quantum bit.

[0135] For the simulation of items H2, H3, and H4, we can refer to item H1 and obtain:

[0136] U2(H2,θ2)=CNOT(0,1)RZ(1,2θ2)CNOT(0,1)

[0137] U3(H3,θ3)=CNOT(0,2)CNOT(1,2)RZ(2,2θ3)CNOT(1,2)CNOT(0,2)

[0138] U4(H4,θ4)=H(0)CNOT(0,1)RZ(1,2θ4)CNOT(0,1)H(0)

[0139] S204: Determine the chemical energy of the target substance according to the measurement result of the quantum circuit.

[0140] Specifically, determining the chemical energy of the target substance according to the measurement result of the quantum circuit may include:

[0141] According to the ground state wave function and the optimal variational parameter, the energy of the target substance is calculated by the following formula:

[0142] E=<Ψ(θ)|H|Ψ(θ)>

[0143] Wherein, E is the energy of the target substance, and H is the Hamiltonian of the target substance.

[0144] Hamiltonian is a physical concept in classical mechanics. In quantum mechanics, the physical quantities of classical mechanics become corresponding operators, and Hamiltonian corresponds to the Hamiltonian operator. Hamiltonian can be understood as the sum of the kinetic energy of all particles of the target substance plus the potential energy of the particles related to the target substance. For different situations or numbers of particles, Hamiltonian is different because it includes the sum of the kinetic energy of the particles and the potential energy function corresponding to this situation, generally represented by H.

[0145] It can be seen that the present invention converts a cluster operator in the form of a fermion into a cluster operator in the form of a Pauli operator, then determines a target cluster operator for constructing a quantum circuit from the cluster operator in the form of a Pauli operator, constructs a quantum circuit according to the target cluster operator and runs the quantum circuit to obtain a measurement result of the quantum circuit, and finally determines the chemical energy of the target substance according to the measurement result of the quantum circuit. It improves the calculation speed of solving the target substance by predetermining the cluster operator excitation term and the number of excitation terms in the form of a Pauli operator of the target substance, thereby promoting the further development of quantum chemical simulation applications.

[0146] See also Figure 3 , Figure 3 is a schematic diagram of a target material energy calculation device provided by an embodiment of the present invention, and Figure 2 Corresponding to the process shown, the device includes:

[0147] A conversion module 301, used for converting the cluster operator in the form of fermion into the cluster operator in the form of Pauli operator;

[0148] A first determining module 302 is used to determine target cluster operators for constructing quantum circuits from the cluster operators in the Pauli operator form, wherein the number of the target cluster operators is less than the number of the cluster operators in the Pauli operator form;

[0149] An acquisition module 303 is used to construct a quantum circuit according to the target cluster operator and run the quantum circuit to obtain a measurement result of the quantum circuit, wherein the initial state of the quantum circuit is the Hartree Fock state;

[0150] The second determination module 304 is used to determine the chemical energy of the target substance according to the measurement result of the quantum circuit.

[0151] Specifically, the conversion module includes:

[0152] A mapping unit is used to select a mapping method to transform the cluster operator of the target substance in the form of fermions into the cluster operator in the form of Pauli operators; wherein the mapping method includes one of Jordan-Wigner transformation, Parity transformation and Bravyi-Kitaev transformation.

[0153] Specifically, the module is obtained, including:

[0154] A construction unit is used to construct the target cluster operator excitation term and a quantum circuit corresponding to the number of excitation terms, wherein the quantum circuit is used to evolve the quantum bit from the Hartree Fock state to the target state described by the ground state wave function of the target substance, and the target state is used as the measurement result of the quantum circuit; wherein the ground state wave function |Ψ(θ)> satisfies θ is the optimal variational parameter, T is the cluster operator, is a unitary operator, |ψ> HF is the Hartree Fock state of the target substance.

[0155] Specifically, before the construction unit, the device further includes:

[0156] An obtaining unit, used for obtaining a group of quantum bits, wherein the number of the quantum bits is determined according to the target cluster operator excitation term in the form of the target substance Pauli operator and the number of excitation terms, wherein the initial state of the quantum bit is |0>;

[0157] A construction unit is used to construct a first quantum functional module that evolves the initial state into the Hartree Fock state.

[0158] Specifically, the construction unit includes:

[0159] A construction subunit is used to construct, based on the first quantum function module, a second quantum function module that evolves the Hartree Fock state into a ground state wave function of the target substance, so as to generate the target cluster operator excitation term and a quantum circuit corresponding to the number of excitation terms.

[0160] Specifically, the second determining module includes:

[0161] A calculation unit is used to calculate the energy of the target substance according to the ground state wave function and the optimal variational parameter by the following formula:

[0162] E=<Ψ(θ)|H|Ψ(θ)>

[0163] Wherein, E is the energy of the target substance, and H is the Hamiltonian of the target substance.

[0164] Compared with the prior art, the present invention first converts a cluster operator in the form of a fermion into a cluster operator in the form of a Pauli operator, then determines a target cluster operator for constructing a quantum circuit from the cluster operator in the form of a Pauli operator, constructs a quantum circuit according to the target cluster operator and runs the quantum circuit to obtain a measurement result of the quantum circuit, and finally determines the chemical energy of the target substance according to the measurement result of the quantum circuit. By predetermining the cluster operator excitation term and the number of excitation terms in the form of a Pauli operator of the target substance, the present invention improves the calculation speed of solving the target substance and promotes the further development of quantum chemical simulation applications.

[0165] An embodiment of the present invention further provides a storage medium, in which a computer program is stored, wherein the computer program is configured to execute the steps of any of the above method embodiments when running.

[0166] Specifically, in this embodiment, the above storage medium may be configured to store a computer program for performing the following steps:

[0167] S201: converting the cluster operator in the form of a fermion into the cluster operator in the form of a Pauli operator;

[0168] S202: determining target cluster operators for constructing quantum circuits from the cluster operators in the Pauli operator form, wherein the number of the target cluster operators is less than the number of the cluster operators in the Pauli operator form;

[0169] S203: constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit, wherein the initial state of the quantum circuit is the Hartree Fock state;

[0170] S204: Determine the chemical energy of the target substance according to the measurement result of the quantum circuit.

[0171] Specifically, in this embodiment, the above-mentioned storage medium may include but is not limited to: a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk, and other media that can store computer programs.

[0172] An embodiment of the present invention further provides an electronic device, comprising a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0173] Specifically, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor, and the input / output device is connected to the processor.

[0174] Specifically, in this embodiment, the processor may be configured to perform the following steps through a computer program:

[0175] S201: converting the cluster operator in the form of a fermion into the cluster operator in the form of a Pauli operator;

[0176] S202: determining target cluster operators for constructing quantum circuits from the cluster operators in the Pauli operator form, wherein the number of the target cluster operators is less than the number of the cluster operators in the Pauli operator form;

[0177] S203: constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit, wherein the initial state of the quantum circuit is the Hartree Fock state;

[0178] S204: Determine the chemical energy of the target substance according to the measurement result of the quantum circuit.

[0179] The embodiment of the present invention may also provide a quantum computer operating system, which realizes the determination of the chemical energy of the target substance according to any of the above method embodiments provided in the embodiment of the present invention.

[0180] An embodiment of the present application may also provide a quantum computer, wherein the quantum computer includes the quantum computer operating system.

[0181] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made according to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. A method for determining the chemical energy of a target substance, characterized in that: The ground state wave function of the target substance is determined according to a unitary operator and a Hartree Fock state, and the unitary operator is determined according to a cluster operator; the method comprises: converting the cluster operator in fermion form into the cluster operator in Pauli operator form; Determining target cluster operators for constructing quantum circuits from the cluster operators in the Pauli operator form, wherein the number of the target cluster operators is less than the number of the cluster operators in the Pauli operator form; Constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit, wherein the initial state of the quantum circuit is the Hartree Fock state; The chemical energy of the target substance is determined according to the measurement result of the quantum circuit.

2. The method according to claim 1, characterized in that The Hartree Fock state of the target substance is determined according to the electron information and electron spin orbit information of the target substance.

3. The method according to claim 2, characterized in that The step of converting the cluster operator in the form of a fermion into the cluster operator in the form of a Pauli operator comprises: A mapping method is selected to transform the cluster operator of the target substance in the form of fermions into the cluster operator in the form of Pauli operators; wherein the mapping method includes one of Jordan-Wigner transformation, Parity transformation and Bravyi-Kitaev transformation.

4. The method according to claim 3, characterized in that: The step of constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit includes: Constructing a quantum circuit corresponding to the target cluster operator excitation term and the number of excitation terms, the quantum circuit is used to evolve the quantum bit from the Hartree Fock state to the target state described by the ground state wave function of the target substance, and taking the target state as the measurement result of the quantum circuit; wherein the ground state wave function |Ψ(θ)> satisfies θ is the optimal variational parameter, T is the cluster operator, is a unitary operator, |ψ> HF is the Hartree Fock state of the target substance.

5. The method according to claim 4, characterized in that Before constructing the target cluster operator excitation terms and the quantum circuit corresponding to the number of excitation terms, the method further includes: A group of quantum bits is obtained, wherein the number of the quantum bits is determined according to the target cluster operator excitation term in the form of the target substance Pauli operator and the number of excitation terms, wherein the initial state of the quantum bit is |0>; A first quantum functional module is constructed to evolve the initial state into the Hartree Fock state.

6. The method according to claim 5, characterized in that The step of constructing the target cluster operator excitation term and the quantum circuit corresponding to the number of excitation terms includes: Based on the first quantum function module, a second quantum function module is constructed to evolve the Hartree Fock state into a ground state wave function of the target substance, so as to generate the target cluster operator excitation term and a quantum circuit corresponding to the number of excitation terms.

7. The method according to claim 6, characterized in that Determining the chemical energy of the target substance according to the measurement result of the quantum circuit includes: According to the ground state wave function and the optimal variational parameter, the energy of the target substance is calculated by the following formula: E=<Ψ(θ)|H|Ψ(θ)> Wherein, E is the energy of the target substance, and H is the Hamiltonian of the target substance.

8. A device for determining the chemical energy of a target substance, characterized in that: The device comprises: A conversion module, used for converting the cluster operator in the form of fermion into the cluster operator in the form of Pauli operator; A first determination module is used to determine target cluster operators for constructing quantum circuits from the cluster operators in the Pauli operator form, wherein the number of the target cluster operators is less than the number of the cluster operators in the Pauli operator form; An acquisition module, used for constructing a quantum circuit according to the target cluster operator and running the quantum circuit to obtain a measurement result of the quantum circuit, wherein the initial state of the quantum circuit is the Hartree Fock state; The second determination module is used to determine the chemical energy of the target substance according to the measurement result of the quantum circuit.

9. A storage medium, characterized in that: The storage medium stores a computer program, wherein the computer program is configured to execute the method according to any one of claims 1 to 7 when executed.

10. An electronic device comprising a memory and a processor, characterized in that: A computer program is stored in the memory, and the processor is configured to run the computer program to perform the method according to any one of claims 1 to 7.

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