Variational quantum eigen-solving method and device based on physical symmetry, medium and equipment

Abstract

The application relates to the technical field of quantum computing and quantum chemistry cross, and particularly discloses a variational quantum eigen solution method, device, medium and equipment based on physical symmetry, which comprises the following steps: obtaining target system information, wherein the target system information comprises a Hamiltonian of a target system, the number of electrons, orbital energy distribution and symmetry; reducing the Hamiltonian based on the number of electrons and the orbital energy distribution, converting the reduced Hamiltonian from a fermion operator form into a Pauli operator form to obtain a Pauli Hamiltonian; determining a variational quantum circuit based on the symmetry; and solving the Pauli Hamiltonian based on the variational quantum circuit to obtain the ground state energy of the target system. The application solves the problem that the number of quantum computing bits is difficult to adapt to a large chemical system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum computing and quantum chemistry, and particularly relates to a variational quantum eigenvalue solving method, device, medium and equipment based on physical symmetry. BACKGROUND

[0002] The variational quantum eigenvalue solver (VQE) is a classical-quantum hybrid algorithm, which generates a trial state through a parameterized quantum circuit, combines a classical optimizer to minimize the expectation value of a molecular Hamiltonian, and finally solves the ground state energy. However, the traditional VQE needs to assign a quantum bit to each spin orbit, such as 12 quantum bits for a LiH molecule. Limited by the number of bits of the current quantum hardware, only small molecules such as hydrogen and lithium hydride can be processed, and it is difficult to extend to larger chemical systems such as benzene rings. SUMMARY

[0003] In order to overcome the above technical problems existing in the prior art, the embodiments of the present application provide a variational quantum eigenvalue solving method, system, medium and device based on physical symmetry.

[0004] In order to achieve the above purpose, the embodiments of the present application provide a variational quantum eigenvalue solving method based on physical symmetry, which comprises: obtaining target system information, the target system information comprising a Hamiltonian of a target system, a number of electrons, an orbital energy distribution and a symmetry; reducing the Hamiltonian based on the number of electrons and the orbital energy distribution, converting the reduced Hamiltonian from a fermion operator form to a Pauli operator form to obtain a Pauli Hamiltonian; determining a variational quantum circuit based on the symmetry; and solving the Pauli Hamiltonian based on the variational quantum circuit to obtain the ground state energy of the target system.

[0005] Preferably, the reducing the Hamiltonian based on the number of electrons and the orbital energy distribution comprises: determining the orbital energy as the active orbital in the active space approximation algorithm based on the orbital energy distribution; obtaining the number of active orbitals, and determining the number of target spin orbitals based on the number of active orbitals; and reducing the Hamiltonian based on the number of electrons and the number of target spin orbitals.

[0006] Preferably, the converting the reduced Hamiltonian from a fermion operator form to a Pauli operator form comprises: converting the reduced Hamiltonian from a fermion operator form to a Pauli operator form according to a preset encoding mode; and the preset encoding mode comprises a JW transformation and a BK transformation.

[0007] Preferably, the determining a variational quantum circuit based on the symmetry comprises: determining the quantum route as a symmetry preserving mode when the target system has high symmetry; and determining the quantum route as a hardware efficient mode when the target system does not have high symmetry.

[0008] Preferably, the solving the Pauli Hamiltonian based on the variational quantum circuit comprises: running the variational quantum circuit at different circuit depths to obtain a circuit depth evaluation index, the circuit depth evaluation index comprising a calculation time consumption and a convergence accuracy; and taking the circuit depth with the shortest calculation time consumption and the highest convergence accuracy as the optimal circuit depth.

[0009] Preferably, the solving the Pauli Hamiltonian based on the variational quantum circuit further comprises: constructing a target variational quantum circuit based on the optimal depth; initializing a circuit parameter of the target variational quantum circuit; running the target variational quantum circuit to obtain an expected value of the Pauli Hamiltonian; inputting the expected value into a classical optimizer to generate a new circuit parameter; and repeating the above steps until the expected value converges to a minimum value, and taking the minimum value as the ground state energy of the target system.

[0010] In a second aspect, a variational quantum eigenstate solving device based on physical symmetry is provided, and the device comprises: an acquisition module configured to acquire target system information, the target system information comprising a Hamiltonian of a target system, an electron number, an orbital energy distribution and a symmetry; a conversion module configured to reduce the Hamiltonian based on the electron number and the orbital energy distribution, and convert the reduced Hamiltonian from a fermion operator form to a Pauli operator form; a determination module configured to determine a variational quantum circuit based on the symmetry; and a solving module configured to solve the Hamiltonian in the Pauli operator form based on the variational quantum circuit to obtain a ground state energy of the target system.

[0011] In a third aspect, a storage medium is provided, and the storage medium stores a computer program, wherein the computer program is configured to execute the method described in any one of the aspects when the computer program is run.

[0012] In a fourth aspect, an electronic device is provided, and the electronic device comprises a memory and a processor, the memory stores a computer program, and the processor is configured to execute the computer program to execute the method described in any one of the aspects.

[0013] The technical scheme provided by the present application has at least the following technical effects:

[0014] The present application solves the problem that the number of quantum bits is difficult to adapt to a large chemical system by reducing the Hamiltonian based on the electron number and the orbital energy distribution, retaining only active orbits that play a key role in the ground state energy, and selecting a corresponding quantum circuit according to the symmetry of the molecule, so that the quantum computing task of a large chemical system can be run on a smaller quantum device.

[0015] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings are included to provide a further understanding of embodiments of the application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the application, and together with the description serve to explain embodiments of the application, but do not limit embodiments of the application. In the drawings:

[0017] Figure 1 A hardware structure block diagram of a computer terminal of a variational quantum eigen-solving method based on physical symmetry is provided for an exemplary embodiment of the present application.

[0018] Figure 2 A flowchart of a variational quantum eigen-solving method based on physical symmetry is provided for an exemplary embodiment of the present application.

[0019] Figure 3 A variational quantum circuit structure diagram of one layer depth of a benzene molecule is provided for an exemplary embodiment of the present application.

[0020] Figure 4 A structure diagram of an entanglement gate in a variational quantum circuit of a benzene molecule is provided for an exemplary embodiment of the present application.

[0021] Figure 5 A structure diagram of a variational quantum eigen-solving device based on physical symmetry is provided for an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0022] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0023] The terms "system" and "network" in the embodiments of the present application can be used interchangeably. "Multiple" means two or more, and therefore "multiple" in the embodiments of the present application can also be understood as "at least two". "And / or", which describes the association relationship of the associated objects, means that there can be three relationships, for example, A and / or B can mean that there are three cases of A alone, A and B together, and B alone. In addition, the character " / ", if not specially stated, generally represents an "or" relationship between the associated objects. In addition, it should be understood that in the description of the embodiments of the present application, the terms "first", "second", etc. are used only for the purpose of distinguishing the description, and cannot be understood as indicating or implying relative importance, nor can it be understood as indicating or implying order.

[0024] Reference should be made to Figure 1 , Figure 1 A hardware structure block diagram of a computer terminal of a variational quantum eigen-solving method based on physical symmetry is provided for an exemplary embodiment of the present application. As shown in FIG. 1, the computer terminal includes a processor 10, a memory 20, an input device 30, an output device 40, and a communication interface 50.Figure 1 As shown, a computer terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. Optionally, the computer terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the computer terminal described above. For example, the computer terminal may also include components that are more complex than those described above. Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0025] The memory 104 can be used to store software programs and modules for application software, such as the program instructions / modules corresponding to the experimental state of the system based on spin symmetry and equivalent particle properties in this embodiment of the application. The processor 102 executes various functional applications and data processing by running the software programs and modules stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to a computer terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0026] The transmission device 106 is used to receive or send data via a network. Specific examples of the network described above may include a wireless network provided by a communication provider for the computer terminal. In one example, the transmission device 106 includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device 106 may be a Radio Frequency (RF) module, used for wireless communication with the Internet.

[0027] It should be noted that a real quantum computer is a hybrid structure, which includes two parts: one part is a classical computer responsible for performing classical computing and control; the other part is a quantum device responsible for running a quantum program to implement quantum computing. The quantum program is a sequence of instructions written in a quantum language such as QRunes language that can run on a quantum computer, which supports quantum logic gate operations and ultimately realizes quantum computing. Specifically, the quantum program is a sequence of instructions for operating quantum logic gates in a certain time sequence.

[0028] In practical applications, due to the limitation of the development of quantum device hardware, quantum computing simulation is usually needed to verify quantum algorithms, quantum applications, and the like. Quantum computing simulation is a process of simulating the running of a quantum program corresponding to a specific problem by means of a virtual architecture (i.e., a quantum virtual machine) built by the resources of an ordinary computer. Generally, a quantum program corresponding to a specific problem needs to be constructed. The quantum program referred to in the embodiments of the present application is a program written in a classical language representing qubits and their evolution, in which quantum bits, quantum logic gates, and the like related to quantum computing are represented by corresponding classical codes.

[0029] As an embodiment of a quantum program, the variational quantum circuit, also known as a quantum logic circuit, is the most commonly used general quantum computing model, representing a circuit for operating qubits in an abstract concept, which consists of qubits, a circuit (time line), and various quantum logic gates, and finally the result needs to be read out through a quantum measurement operation.

[0030] Unlike traditional circuits connected by metal wires to transmit voltage signals or current signals, in a variational quantum circuit, the circuit can be regarded as being connected by time, that is, the state of a qubit naturally evolves over time, and in this process, it is operated according to the instructions of a Hamiltonian operator until it encounters a logic gate.

[0031] A quantum program corresponds to a total variational quantum circuit as a whole, and the quantum program described in the present application refers to the total variational quantum circuit, wherein the total number of qubits in the total variational quantum circuit is the same as the total number of qubits of the quantum program. It can be understood that a quantum program can be composed of a variational quantum circuit, a measurement operation for qubits in the variational quantum circuit, a register for saving measurement results, and a control flow node (jump instruction). A variational quantum circuit can contain tens, hundreds, or even thousands of quantum logic gate operations. The execution process of a quantum program is a process of executing all quantum logic gates in a certain time sequence. It should be noted that the time sequence is the time order in which individual quantum logic gates are executed.

[0032] It should be noted that in classical computing, the most basic unit is a bit, and the most basic control mode is a logic gate, which can be combined to achieve the purpose of controlling the circuit. Similarly, the way to handle quantum bits is quantum logic gates. Using quantum logic gates, quantum states can evolve, and quantum logic gates are the basis of variational quantum circuits, including single-bit quantum logic gates such as Hadamard gates, Pauli-X gates, Pauli-Y gates, Pauli-Z gates, RX gates, RY gates, RZ gates, and the like; two-bit or multi-bit quantum logic gates such as CNOT gates, CR gates, CZ gates, iSWAP gates, Toffoli gates, and the like. In quantum computing, limited quantum bits are combined with a variety of logic functions to achieve the effect of operation. However, due to the current limitation of the number of quantum bits, the existing technology can only use small molecules such as hydrogen, lithium hydride, and methane, and it is difficult to implement large chemical systems.

[0033] Please refer to Figure 2 , Figure 2 is a flowchart of a variational quantum eigenvalue solving method based on physical symmetry provided by an embodiment of the present application, and the method comprises:

[0034] S1, obtaining target system information, the target system information comprising Hamiltonian, electron number, orbital energy distribution and symmetry of the target system;

[0035] Specifically, the target system is a chemical molecular model that needs to be simulated. The chemical molecular model can be considered as a molecular structure modeling that a user wants to calculate the ground state energy, for example, including the atomic type, the number of atoms, the atomic coordinates, the charge and the spin multiplicity of the atoms, etc.

[0036] The target system can be determined in the following manner, but is not limited to, the user can input the chemical molecular model information that wants to be simulated on the computer terminal. For example, the user opens the quantum chemical simulation application software of the computer, and the quantum chemical simulation application interface can display the chemical molecular model options to be simulated, such as lithium hydride molecular model, benzene molecular model, etc. The user clicks the chemical molecular model option that wants to be simulated, and the quantum chemical simulation application can determine the chemical molecular model.

[0037] The Hamiltonian is a physical concept in classical mechanics, while in quantum mechanics, the physical quantities of classical mechanics become corresponding operators, and the Hamiltonian corresponds to the Hamiltonian operator. The Hamiltonian can be understood as the sum of the kinetic energy of all particles in the target system plus the potential energy of the particles related to the target system. For different cases or quantities of particles, the Hamiltonian is different because it includes the sum of the kinetic energy of the particles and the potential energy function corresponding to this case, and the electron is the smallest particle.

[0038] Symmetry is the property of a target system that remains unchanged under spatial symmetry operations such as rotation around an axis, reflection about a plane, center inversion, and image rotation, and is characterized by the point group of the target system.

[0039] When the target system is determined, the Hamiltonian, the number of electrons, the orbital energy distribution, and the symmetry of the target system can be determined.

[0040] For benzene molecules, due to the bit number limitation, it is difficult to adapt to the current quantum computer, and therefore, after the Hamiltonian of the target system is determined, it needs to be optimized.

[0041] S2, based on the number of electrons and the orbital energy distribution, reducing the Hamiltonian, converting the reduced Hamiltonian from fermion operator form to Pauli operator form to obtain a Pauli Hamiltonian.

[0042] In the embodiment of the present application, the reducing the Hamiltonian based on the number of electrons and the orbital energy distribution comprises: based on the orbital energy distribution, determining the space orbitals with energy in the middle as active orbitals by using the active space approximation algorithm; obtaining the number of active orbitals, determining the target spin-orbital number based on the number of active orbitals; and reducing the Hamiltonian based on the number of electrons and the target spin-orbital number.

[0043] Specifically, the active space approximation algorithm is to approximately consider that the several space orbitals with lower energy are certainly occupied by electrons, the several space orbitals with higher energy are certainly not occupied by electrons, and the production and annihilation of electrons only occur in the several space orbitals with energy in the middle, i.e. active orbitals. After the number of active orbitals is determined, since each space orbital corresponds to two spin states, the number of spin orbitals corresponding to the number of active orbitals can be determined, and then the original spin-orbital number is compressed to the number of spin orbitals corresponding to the number of active orbitals, and only the Hamiltonian corresponding to the active orbitals is concerned during calculation, thereby reducing the bit number during quantum calculation.

[0044] By using the active space approximation algorithm and Hamiltonian reduction, a larger chemical system that cannot be processed due to the bit number limitation can be simplified into a smaller sub-problem, which adapts to the bit number limitation of the current quantum computer.

[0045] The reduced Hamiltonian is still in fermion form, and the fermion form Hamiltonian cannot be directly evolved on the circuit, so it is necessary to convert the fermion form Hamiltonian solution into a process readable by the quantum circuit, which is called mapping. It should be noted that the mapping is only to express the Hamiltonian in a different form, and the system energy information represented by each type of Hamiltonian is equivalent. In addition, for a quantum simulation circuit or a real quantum chip, the Pauli operator is easier to operate and generate, so the fermion form Hamiltonian corresponding to the target system can be converted into the Pauli Hamiltonian of the target system, which is convenient for subsequent simulation operations.

[0046] In the embodiment of the present application, the conversion of the reduced Hamiltonian from the fermionic operator form to the Pauli operator form comprises: converting the reduced Hamiltonian from the fermionic operator form to the Pauli operator form according to a preset encoding mode, that is, mapping the reduced Hamiltonian to a qubit state according to the preset encoding mode.

[0047] Specifically, the preset encoding mode includes but is not limited to JW transformation and BK transformation, which are prior art and the working principle thereof will not be described in detail in the embodiment of the present application.

[0048] For example, the embodiment of the present application selects BK transformation to convert the reduced Hamiltonian of benzene molecule.

[0049] Through the preset encoding mode, the Hamiltonian can be converted from the fermionic operator form to the Pauli operator form, which provides a data basis for subsequent ground state energy solving.

[0050] After obtaining the Pauli Hamiltonian, it is necessary to construct a variational quantum circuit to solve the Pauli Hamiltonian, but the prior art randomly selects the type of variational quantum circuit, resulting in poor solving effect.

[0051] S3, determining a variational quantum circuit based on the symmetry, solving the Pauli Hamiltonian based on the variational quantum circuit, and obtaining the ground state energy of the target system.

[0052] In the embodiment of the present application, the determination of the variational quantum circuit based on the symmetry comprises: when the target system has high symmetry, determining the quantum circuit to be a symmetry preserving mode; and when the target system does not have high symmetry, determining the quantum circuit to be a hardware efficient mode.

[0053] Specifically, the hardware efficient mode is a variational variational quantum circuit construction method designed based on the hardware characteristics of a quantum computer, mainly by adapting the basic quantum gates of the hardware (such as single-bit rotation gates, two-bit gates between adjacent quantum bits) to construct a parameterized circuit. Through the design of a specific entanglement gate structure, a method for strictly preserving the symmetry of the target system (such as electron number conservation, spin symmetry, etc.) during the evolution of the variational quantum circuit. According to the symmetry of the target system, the embodiment of the present application can construct different variational quantum circuits to improve the calculation accuracy and reduce the calculation time.

[0054] For example, if the high symmetry of the benzene molecule is not considered, the hardware efficient mode is directly selected, and the structure diagram of the variable molecular circuit is as shown in Figure 3As shown, the construction process is: each qubit is initially created by a Hadamard gate to create an electronic orbital (each spin orbital corresponds to a qubit), then the orbital electron occupation number is regulated by a single-bit parameterized RY gate and RX gate, and then the qubits are parameterized entangled by a "CNOT+RY+RX" combination. Based on the structure of "single-layer single-bit gate + single-layer entanglement gate", a layer depth of the variational quantum circuit is formed. Randomize the circuit parameters, and the variational quantum circuit based on the structure takes 185 seconds, and the output ground state energy is -2.1835724920829565. The variational quantum circuit is sensitive to the initial parameters, and the effect is not ideal after randomizing the circuit parameters, and the effect is worse as the circuit depth deepens. Obviously, if the symmetry of the target system is not considered, directly selecting a hardware-efficient way will greatly reduce the calculation accuracy and increase the calculation time.

[0055] In order to avoid unnecessary calculation overhead due to excessive depth, while ensuring the basic expression ability of the circuit to the target molecular state, after determining the variational quantum circuit, the circuit depth thereof also needs to be determined.

[0056] In the embodiment of the present application, the solving of the Pauli Hamiltonian based on the variational quantum circuit comprises: running the variational quantum circuit under different circuit depths to obtain a circuit depth evaluation index, the circuit depth evaluation index comprising a calculation time and a convergence accuracy (ground state energy accuracy); and taking the circuit depth with the shortest calculation time and the highest convergence accuracy as the optimal circuit depth.

[0057] In a possible implementation, the initial circuit depth can be determined according to experience, or the initial circuit depth can be determined according to the number of active orbitals. The greater the number of active orbitals, the greater the initial circuit depth. In this embodiment, it is not limited to which way to choose. Then, based on the initial circuit depth, one layer is gradually increased for simulation operation on a quantum computer, and the corresponding operation result is recorded. Finally, the circuit depth with the shortest calculation time and the highest convergence accuracy is selected as the optimal circuit depth. In actual application, the technical personnel find that the hardware-efficient circuit is sensitive to the initial circuit parameters. Therefore, the parameter sensitivity can also be considered, that is, after initializing the circuit parameters, the dispersion degree of the operation result can be considered during operation. The optimal circuit depth is determined based on the dispersion degree, the shortest calculation time and the highest convergence accuracy.

[0058] The embodiment dynamically optimizes the circuit depth to minimize the complexity of the variational quantum circuit and the consumption of calculation resources while ensuring the convergence accuracy, and reduces the sensitivity of parameter optimization.

[0059] After determining the optimal depth, the ground state energy needs to be solved by a quantum-classical coordination optimization process.

[0060] In the embodiment of the present application, the solving the Pauli Hamiltonian based on the variational quantum circuit further includes: constructing a target variational quantum circuit based on the optimal depth; initializing the circuit parameters of the target variational quantum circuit; running the target variational quantum circuit to obtain the expected value of the Pauli Hamiltonian; inputting the expected value into a classical optimizer to generate new circuit parameters; repeating the above steps until the expected value converges to a minimum value, and taking the minimum value as the ground state energy of the target system.

[0061] In a possible implementation, based on the optimal depth, the single-bit gate (RY, RX) and the entanglement gate are cascaded in the structure of "single-layer single-bit gate + single-layer entanglement gate" to form a target variational quantum circuit. Taking the symmetry preserving circuit of benzene molecule as an example, when the optimal depth is 2, the structure is: single-layer RY / RX gate→single-layer symmetry entanglement gate→repeat 2 times. In order to avoid local optimization of the circuit parameters, the strategy of random initialization and symmetry constraint is adopted, that is, the rotation angle of the single-bit gate is randomly taken in a preset range, and the parameter of the entanglement gate is limited in a preset interval according to the symmetry of the target system. Then, the initialized circuit parameters are input into the variational quantum circuit, the circuit is run through the quantum computer or the simulator to generate a quantum state, and the expected value is calculated through the inner product of the Pauli Hamiltonian and the quantum state. The value is the energy estimate value under the current parameters. The expected value is input into a classical optimizer, such as gradient descent, Adam, etc. The classical optimizer adjusts the circuit parameters according to the change direction of the expected value to generate a new parameter set. Repeat the steps until the expected value of multiple iterations changes less than a preset threshold. At this time, it is considered that the circuit parameters converge, and the final minimum energy is the ground state energy of the target system, and the ground state energy is output.

[0062] For example, taking benzene molecule as an example, the symmetry preserving mode is selected, the entanglement gate in the hardware efficient mode is replaced by the entanglement gate shown in Figure 4 , and the variational quantum circuit is used as the variational quantum circuit of benzene molecule for quantum eigenvalue solving. After 2 layers of depth and 50 times of optimizer iteration, the final ground state energy is-2.18357 Hartree, and the time consumption is only 29 seconds, which significantly improves the accuracy and efficiency compared with the hardware efficient circuit.

[0063] Referring to Figure 5 , Figure 5 is a structural schematic diagram of a variational quantum eigenvalue solving device based on physical symmetry provided by the embodiment of the present application, and corresponds to the flow shown in Figure 2 , the device comprises:

[0064] The acquisition module 501 is configured to acquire target system information, and the target system information includes the Hamiltonian of the target system, the number of electrons, the orbital energy distribution and the symmetry.

[0065] The conversion module 502 is used to reduce the Hamiltonian based on the number of electrons and the orbital energy distribution, and to convert the reduced Hamiltonian from the fermion operator form to the Pauli operator form.

[0066] Determining module 503 is used to determine the variable quantum circuit based on the symmetry;

[0067] The solver module 504 is used to solve the Hamiltonian in Pauli operator form based on the variable quantum circuit to obtain the ground state energy of the target system.

[0068] This invention, through reduction based on the number of electrons and orbital energy distribution, retains only the active orbitals that play a key role in the ground state energy, and selects the corresponding quantum routes according to the symmetry of the molecule. This enables quantum computing tasks for large chemical systems to run on smaller-scale quantum devices, solving the problem that the current number of quantum computing qubits is difficult to adapt to large chemical systems.

[0069] This invention also provides a storage medium storing a computer program, wherein the computer program is configured to execute the steps in any of the above-described method embodiments when running.

[0070] Specifically, in this embodiment, the storage medium can be configured as a computer program for performing the following steps:

[0071] S1, Obtain target system information, including the Hamiltonian, number of electrons, orbital energy distribution, and symmetry of the target system;

[0072] S2, based on the number of electrons and the orbital energy distribution, reduce the Hamiltonian, and convert the reduced Hamiltonian from the fermion operator form to the Pauli operator form to obtain the Pauli Hamiltonian;

[0073] S3, Determine the variable quantum circuit based on the aforementioned symmetry;

[0074] S4. Solve the Pauli Hamiltonian based on the variable quantum circuit to obtain the ground state energy of the target system.

[0075] Specifically, in this embodiment, the storage medium may include, but is not limited to, USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks, and other media capable of storing computer programs.

[0076] The embodiment of the present application also provides an electronic device, comprising a memory and a processor, characterized in that the memory stores a computer program, and the processor is arranged to run the computer program to execute the steps in any of the method embodiments.

[0077] Specifically, the electronic device can further comprise a transmission device connected with the processor and an input and output device connected with the processor.

[0078] Specifically, in the embodiment, the processor can be arranged to execute the following steps through the computer program:

[0079] S1, obtaining target system information, wherein the target system information comprises a Hamiltonian of a target system, an electron number, an orbital energy distribution and a symmetry;

[0080] S2, reducing the Hamiltonian based on the electron number and the orbital energy distribution, converting the reduced Hamiltonian from a fermion operator form to a Pauli operator form to obtain a Pauli Hamiltonian;

[0081] S3, determining a variational quantum circuit based on the symmetry;

[0082] S4, solving the Pauli Hamiltonian based on the variational quantum circuit to obtain a ground state energy of the target system.

[0083] The optional implementation manners of the embodiment of the present application are described in detail above in combination with the drawings, however, the embodiment of the present application is not limited to the specific details in the above implementation manners, and various simple modifications can be made to the technical solution of the embodiment of the present application within the technical concept of the embodiment of the present application, and these simple modifications all belong to the protection scope of the embodiment of the present application.

[0084] In addition, it should be noted that each specific technical feature described in the above specific implementation manners can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the embodiment of the present application will not further describe various possible combination manners.

[0085] In addition, any combination can be made between various different implementation manners of the embodiment of the present application, as long as it does not deviate from the idea of the embodiment of the present application, and it should be considered as the disclosed content of the embodiment of the present application.

Claims

1. A variational quantum eigenvalue solution method based on physical symmetry, characterized in that, include: Obtain information about the target system, including the Hamiltonian, number of electrons, orbital energy distribution, and symmetry of the target system, wherein the target system is a chemical molecular model to be simulated; Based on the number of electrons and the orbital energy distribution, the Hamiltonian is reduced, and the reduced Hamiltonian is converted from the fermion operator form to the Pauli operator form to obtain the Pauli Hamiltonian. The variable quantum circuit is determined based on the aforementioned symmetry; The Pauli Hamiltonian is solved based on the variable quantum circuit to obtain the ground state energy of the target system; The determination of the variable quantum circuit based on the symmetry includes: When the target system satisfies the preset high symmetry, the quantum route is determined to be a symmetry-preserving mode; When the target system does not satisfy the preset high symmetry, the quantum route is determined to be a hardware-efficient method, and the preset high symmetry is determined based on the point group of the target system; The solution to the Pauli Hamiltonian based on the variable quantum circuit includes: Run the variable quantum circuit at different line depths to obtain line depth evaluation indicators, including computation time and convergence accuracy. The optimal line depth is the line depth that takes the shortest calculation time and has the highest convergence accuracy.

2. The variational quantum eigenvalue solution method based on physical symmetry according to claim 1, characterized in that, The reduction of the Hamiltonian based on the number of electrons and the orbital energy distribution includes: Based on the orbital energy distribution, the active orbit is determined by the active space approximation algorithm, which identifies the space orbit with the central orbital energy. Obtain the number of active orbitals, and determine the target spin orbital number based on the number of active orbitals; The Hamiltonian is reduced based on the number of electrons and the target spin orbital number.

3. The variational quantum eigenvalue solution method based on physical symmetry according to claim 1, characterized in that, The process of converting the reduced Hamiltonian from fermionic operator form to Pauli operator form includes: According to a preset encoding method, the reduced Hamiltonian is converted from fermionic operator form to Pauli operator form; the preset encoding method includes JW transform and BK transform.

4. The variational quantum eigenvalue solution method based on physical symmetry according to claim 1, characterized in that, The solution of the Pauli Hamiltonian based on the variable quantum circuit also includes: Construct the target variable quantum line based on the optimal line depth; Initialize the line parameters of the target variable quantum line; Run the target variable quantum circuit to obtain the expected value of the Pauli Hamiltonian; The desired value is input into the classic optimizer to generate new line parameters; Repeat the above steps until the expected value converges to the minimum value, and take the minimum value as the ground state energy of the target system.

5. A variational quantum eigenvalue solver based on physical symmetry, characterized in that, The device includes: The acquisition module is used to acquire information about the target system, including the Hamiltonian, number of electrons, orbital energy distribution, and symmetry of the target system, which is a chemical molecular model to be simulated. The conversion module is used to reduce the Hamiltonian based on the number of electrons and the orbital energy distribution, and to convert the reduced Hamiltonian from the fermion operator form to the Pauli operator form. The determination module is used to determine the variable quantum circuit based on the symmetry. The solution module is used to solve the Hamiltonian in Pauli operator form based on the variable quantum circuit to obtain the ground state energy of the target system. The determining module is specifically used for: When the target system satisfies the preset high symmetry, the quantum route is determined to be a symmetry-preserving mode; When the target system does not satisfy the preset high symmetry, the quantum route is determined to be a hardware-efficient method, and the preset high symmetry is determined based on the point group of the target system; The solution module is specifically used for: Run the variable quantum circuit at different line depths to obtain line depth evaluation indicators, including computation time and convergence accuracy. The optimal line depth is the line depth that takes the shortest calculation time and has the highest convergence accuracy.

6. A storage medium, characterized in that, The storage medium stores a computer program, wherein the computer program is configured to execute the method described in any one of claims 1-4 when it is run.

7. An electronic device comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to run the computer program to perform the method described in any one of claims 1-4.

Images