CN114512193B - Method for preparing system test state based on spin symmetry and equivalent particle characteristics - Google Patents
Method for preparing system test state based on spin symmetry and equivalent particle characteristics Download PDFInfo
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- CN114512193B CN114512193B CN202210099643.0A CN202210099643A CN114512193B CN 114512193 B CN114512193 B CN 114512193B CN 202210099643 A CN202210099643 A CN 202210099643A CN 114512193 B CN114512193 B CN 114512193B
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Abstract
The application provides a method, a device, electronic equipment and a medium for preparing a system test state based on spin symmetry and equivalent particle characteristics, wherein the method for preparing the system test state based on the spin symmetry and the equivalent particle characteristics comprises the following steps: determining a system, and the track number and the electron number of the system; determining the number of excitation terms and coefficients corresponding to the excitation terms included by the cluster operators of the fermi sub-form of the system according to the number of orbits and the number of electrons of the system based on the spin symmetry and the equivalent particle characteristics; calculating a cluster operator of the Fermi form of the system according to the number of the excitation terms and the coefficients corresponding to the excitation terms; based on the cluster operators of the fermi form of the system, the experimental state of the system is solved. The method and the device belong to the field of quantum computing, solve the technical problem that complex molecules are difficult to simulate in the prior art, save computing resources and improve the simulation efficiency of the complex molecules.
Description
Technical Field
The application belongs to the field of quantum computing, and particularly relates to a method, a device, electronic equipment and a medium for preparing a system test state based on spin symmetry and equivalent particle characteristics.
Background
The quantum computer is a kind of physical device which performs high-speed mathematical and logical operation, stores and processes quantum information according to the law of quantum mechanics. When a device processes and calculates quantum information and operates on a quantum algorithm, the device is a quantum computer. Quantum computers because of their ability to handle mathematical problems more efficiently than conventional computers. It will be appreciated that the key properties of a chemical or material depend on the electronic properties of the chemical or material, so it is important to accurately mimic the electronic properties of the chemical or material.
Theoretical explanations of energy and properties of molecules and materials at the atomic level have long been considered one of the most direct applications of quantum computing, which has received great attention as a new computing paradigm. In recent years, algorithms for acquiring molecular energy by using quantum computers have been focused on, but simulation of complex molecular systems still has difficulty due to the limitations of quantum numbers and coherence time.
Disclosure of Invention
The application aims to provide a method, a device, electronic equipment and a medium for preparing a system test state based on spin symmetry and equivalent particle characteristics, so as to solve the technical problem that complex molecules are difficult to simulate in the prior art, save computing resources and improve the simulation efficiency of the complex molecules.
In a first aspect, the present application provides a method for preparing a system experimental state based on spin symmetry and equivalent particle characteristics, comprising:
determining a system, and the track number and the electron number of the system;
determining the number of excitation terms and coefficients corresponding to the excitation terms included by the cluster operators of the fermi sub-form of the system according to the number of orbits and the number of electrons of the system based on the spin symmetry and the equivalent particle characteristics;
calculating a cluster operator of the Fermi form of the system according to the number of the excitation terms and the coefficients corresponding to the excitation terms;
based on the cluster operators of the fermi form of the system, the experimental state of the system is solved.
Optionally, the determining, based on the spin symmetry and the equivalent particle characteristics, the number of excitation terms and coefficients corresponding to the excitation terms included in the cluster operator of the fermi form of the system according to the number of orbits and the number of electrons of the system includes:
acquiring a Hartree-Fock state of the system according to the track number and the electron number of the system;
according to a pre-selected design mode, the number of excitation terms and coefficients corresponding to the excitation terms included in the cluster operator of the Fermi form of the system are determined based on spin symmetry, equivalent particle characteristics and the Hartree-Fock state of the system.
Optionally, the determining the number of excitation terms included in the cluster operator of the fermi form of the system based on the spin symmetry, the equivalent particle characteristics, and the Hartree-Fock state of the system according to the pre-selected design method includes:
when the proposed mode is a single excitation coupling cluster, confirming that the cluster operator of the Fermi form of the system only comprises a single excitation item number;
based on spin symmetry and Hartree-Fock state, determining the number of the single excitation terms as excitation terms corresponding to the fact that each electron in the system is excited from the original spin direction orbit to other orbits with the same spin direction;
and merging the cluster operators corresponding to the two single-excitation items with the same excitation probability in the determined single-excitation item number based on the equivalent particle characteristics, wherein the single-excitation item coefficient after merging is twice the single-excitation item coefficient before merging.
Optionally, the determining the number of excitation terms included in the cluster operator of the fermi form of the system based on the spin symmetry, the equivalent particle characteristics, and the Hartree-Fock state of the system according to the pre-selected design method includes:
when the pre-selected design mode is a single-double excitation coupling cluster, confirming that the cluster operator of the Fermi form of the system only comprises a single-excitation item number and a double-excitation item number;
Based on spin symmetry and Hartree-Fock state, determining the number of the single excitation terms as excitation terms corresponding to the fact that each electron in the system is excited from the original spin direction orbit to other orbits with the same spin direction; determining the number of the double excitation terms as excitation terms from the original spin direction orbits where each two electrons are located to other two orbits with the same corresponding spin direction;
combining cluster operators corresponding to two single-excitation items with the same excitation probability in the determined single-excitation item number based on the equivalent particle characteristics, wherein the combined single-excitation item coefficient is twice that of the single-excitation item coefficient before combination; and merging the cluster operators corresponding to the two double-excitation terms with the same excitation probability in the determined double-excitation term number, wherein the merged double-excitation term coefficient is twice the double-excitation term coefficient before merging.
Optionally, the solving the experimental state of the system based on the cluster operator of the fermi form of the system includes:
transforming the cluster operators in the form of fermi sub-forms of the system into cluster operators in the form of bubble sharp operators according to a pre-selected mapping mode;
decomposing the cluster operators in the form of the bubble operator into corresponding unitary operator forms and evolving to obtain evolved quantum states; wherein the quantum state after evolution is a test state of the system.
Optionally, the decomposing the cluster operator in the form of the berlite operator into a corresponding unitary operator form and evolving to obtain an evolved quantum state includes:
constructing a quantum simulation circuit based on the unitary operators corresponding to the cluster operators in the form of the bubble operator after decomposition;
and performing simulated evolution according to the quantum simulation circuit to obtain an evolved quantum state.
Optionally, the mapping mode is one of Jordan-Wigner transformation, party transformation, bravyi-Kitaev transformation and segmentParty transformation.
In a second aspect, the present application also provides an apparatus for preparing a system experimental state based on spin symmetry and equivalent particle characteristics, comprising:
the first determining module is used for determining a system and the track number and the electron number of the system;
the second determining module is used for determining the number of excitation terms and coefficients corresponding to the excitation terms, which are included by the cluster operators in the fermi form of the system, according to the orbit number and the electron number of the system based on the spin symmetry and the equivalent particle characteristics;
the calculation module is used for calculating the cluster operators of the fermi sub-form of the system according to the number of the excitation terms and the coefficients corresponding to the excitation terms;
and the solving module is used for determining cluster operators based on the Fermi form of the system and solving the experimental state of the system.
Optionally, the second determining module includes:
the acquisition unit is used for acquiring the Hartree-Fock state of the system according to the track number and the electron number of the system;
and the determining unit is used for determining the number of the excitation terms and the coefficients corresponding to the excitation terms, which are included by the cluster operators of the Fermi form of the system, based on the spin symmetry, the equivalent particle characteristics and the Hartree-Fock state of the system according to a pre-selected design mode.
Optionally, the determining unit is further configured to: when the proposed mode is a single-excitation coupling cluster, determining that the cluster operator of the Fermi form of the system only comprises a single-excitation term number; based on spin symmetry and Hartree-Fock state, determining the number of the single excitation terms as excitation terms corresponding to the fact that each electron in the system is excited from the original spin direction orbit to other orbits with the same spin direction; and merging the cluster operators corresponding to the two single-excitation items with the same excitation probability in the determined single-excitation item number based on the equivalent particle characteristics, wherein the single-excitation item coefficient after merging is twice the single-excitation item coefficient before merging.
Optionally, the determining unit is further configured to: when the pre-selected design mode is a single-double excitation coupling cluster, determining that the cluster operator of the Fermi form of the system only comprises a single-excitation term number and a double-excitation term number; based on spin symmetry and Hartree-Fock state, determining the number of the single excitation terms as excitation terms corresponding to the fact that each electron in the system is excited from the original spin direction orbit to other orbits with the same spin direction; determining the number of the double excitation terms as excitation terms from the original spin direction orbits where each two electrons are located to other two orbits with the same corresponding spin direction; combining cluster operators corresponding to two single-excitation items with the same excitation probability in the determined single-excitation item number based on the equivalent particle characteristics, wherein the combined single-excitation item coefficient is twice that of the single-excitation item coefficient before combination; and merging the cluster operators corresponding to the two double-excitation terms with the same excitation probability in the determined double-excitation term number, wherein the merged double-excitation term coefficient is twice the double-excitation term coefficient before merging.
Optionally, the second determining module further includes:
a transformation unit for transforming the cluster operators in the form of fermi sub-forms of the hierarchy into cluster operators in the form of a berkovich operator according to a pre-selected mapping scheme;
the evolution unit is used for decomposing the cluster operators in the form of the bubble operator into corresponding unitary operator forms and evolving to obtain evolved quantum states; wherein the quantum state after evolution is a test state of the system.
Optionally, the evolution unit is further configured to: constructing a quantum simulation circuit based on the unitary operators corresponding to the cluster operators in the form of the bubble operator after decomposition; and performing simulated evolution according to the quantum simulation circuit to obtain an evolved quantum state.
Optionally, the mapping mode is one of Jordan-Wigner transformation, party transformation, bravyi-Kitaev transformation and segmentParty transformation.
In a third aspect, the present application further provides an electronic device, including:
a processor;
a memory for storing processor-executable instructions;
wherein the processor implements the method of any of the above first aspects by executing the executable instructions.
In a fourth aspect, the present application also provides a computer storage medium having stored thereon computer instructions which when executed by a processor perform the steps of the method of any of the first aspects above.
In the process of preparing the experimental state of the system, the method calculates the Fermi form cluster operator of the system, and the self-rotation symmetry and the equivalent particle characteristics are considered, so that the number of the excitation terms required to be calculated in the Fermi form cluster operator is smaller than the number of the excitation terms without the self-rotation symmetry in the prior art, the complexity of the system is reduced, the calculated amount is reduced when the experimental state of the system is solved, the technical problem that complex molecules are difficult to simulate in the prior art is solved, the calculation resources are saved, the calculation of the energy of the subsequent system is facilitated, and the simulation efficiency of the complex molecules is improved.
Drawings
FIG. 1 is a block diagram of a hardware architecture of a computer terminal for a method for preparing a system experimental state based on spin symmetry and equivalent particle characteristics according to an exemplary embodiment of the present application;
FIG. 2 is a flow chart of a method for preparing a system experimental state based on spin symmetry and equivalent particle characteristics according to an exemplary embodiment of the present application;
fig. 3 is a schematic diagram of a quantum circuit structure corresponding to a design manner according to an exemplary embodiment of the present application;
FIG. 4 is a schematic diagram of hydrogen molecular orbitals provided in an exemplary embodiment of the disclosure;
FIG. 5 is a diagram of an embodiment of an H 1 A corresponding quantum circuit schematic;
FIG. 6 is a diagram of H provided in an exemplary embodiment of the present application 1 And H 2 A corresponding quantum circuit schematic;
FIG. 7 is a diagram of H provided in an exemplary embodiment of the present application 1 、H 2 And H 3 A corresponding quantum circuit schematic;
FIG. 8 is a diagram of H provided in an exemplary embodiment of the present application 1 、H 2 、H 3 And H 4 A corresponding quantum circuit schematic;
FIG. 9 is a diagram of H provided in an exemplary embodiment of the present application 1 、H 2 、H 3 、H 4 And H 5 A corresponding quantum circuit schematic;
fig. 10 is a schematic structural diagram of an apparatus for preparing a system experimental state based on spin symmetry and equivalent particle characteristics according to an exemplary embodiment of the present application.
Detailed Description
The following describes the operation of the computer terminal in detail by taking it as an example. Fig. 1 is a block diagram of a hardware architecture of a computer terminal according to a method for preparing a system experimental state based on spin symmetry and equivalent particle characteristics according to an exemplary embodiment of the present application. As shown in fig. 1, the computer terminal may include one or more (only one is shown in fig. 1) processors 102 (the processor 102 may include, but is not limited to, a microprocessor MCU or a processing device such as a programmable logic device FPGA) and a memory 104 for storing data, and optionally, a transmission device 106 for communication functions and an input-output device 108. It will be appreciated by those skilled in the art that the configuration shown in fig. 1 is merely illustrative and is not intended to limit the configuration of the computer terminal described above. For example, the computer terminal may also include more or fewer components than shown in FIG. 1, or have a different configuration than shown in FIG. 1.
The memory 104 may be used to store software programs and modules of application software, such as program instructions/modules corresponding to the experimental states of the system based on spin symmetry and equivalent particle characteristics in the embodiments of the present application, and the processor 102 executes the software programs and modules stored in the memory 104 to perform various functional applications and data processing, i.e., implement the above-described methods. 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 examples, the memory 104 may further include memory remotely located relative to the processor 102, which may be connected to the computer terminal via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The transmission means 106 is arranged to receive or transmit data via a network. Specific examples of the network described above may include a wireless network provided by a communication provider of a computer terminal. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, NIC) that can connect to other network devices through a base station to communicate with the internet. In one example, the transmission device 106 may be a Radio Frequency (RF) module for communicating with the internet wirelessly.
It should be noted that a real quantum computer is a hybrid structure, which includes two major parts: part of the computers are classical computers and are responsible for performing classical computation and control; the other part is quantum equipment, which is responsible for running quantum programs so as to realize quantum computation. The quantum program is a series of instruction sequences written by a quantum language such as the qlunes language and capable of running on a quantum computer, so that the support of quantum logic gate operation is realized, and finally, quantum computing is realized. Specifically, the quantum program is a series of instruction sequences for operating the quantum logic gate according to a certain time sequence.
In practical applications, quantum computing simulations are often required to verify quantum algorithms, quantum applications, etc., due to the development of quantum device hardware. Quantum computing simulation is a process of realizing simulated operation of a quantum program corresponding to a specific problem by means of a virtual architecture (namely a quantum virtual machine) built by resources of a common computer. In general, it is necessary to construct a quantum program corresponding to a specific problem. The quantum program referred to in the embodiments of the present application is a program written in a classical language to characterize a qubit and its evolution, where the qubit, a quantum logic gate, etc. related to quantum computation are all represented by corresponding classical codes.
Quantum circuits, which are one embodiment of quantum programs, also weigh sub-logic circuits, are the most commonly used general quantum computing models, representing circuits that operate on qubits under an abstract concept, the composition of which includes qubits, circuits (timelines), and various quantum logic gates, and finally the results often need to be read out by quantum measurement operations.
Unlike conventional circuits, which are connected by metal lines to carry voltage or current signals, in a quantum circuit, the circuit can be seen as being connected by time, i.e., the state of the qubit naturally evolves over time, as indicated by the hamiltonian operator, during which it is operated until a logic gate is encountered.
A quantum program is generally corresponding to a total quantum circuit, where the quantum program refers to the total quantum circuit, and the total number of qubits in the total quantum circuit is the same as the total number of qubits in the quantum program. It can be understood that: one quantum program may consist of a quantum circuit, a measurement operation for the quantum bits in the quantum circuit, a register to hold the measurement results, and a control flow node (jump instruction), and one quantum circuit may contain several tens to hundreds or even thousands of quantum logic gate operations. The execution process of the quantum program is a process of executing all quantum logic gates according to a certain time sequence. Note that the timing is the time sequence in which a single quantum logic gate is executed.
It should be noted that in classical computation, the most basic unit is a bit, and the most basic control mode is a logic gate, and the purpose of the control circuit can be achieved by a combination of logic gates. Similarly, the way in which the qubits are handled is a quantum logic gate. Quantum logic gates are used, which are the basis for forming quantum circuits, and include single-bit quantum logic gates, such as Hadamard gates (H gates, ada Ma Men), bery-X gates (X gates), bery-Y gates (Y gates), bery-Z gates (Z gates), RX gates, RY gates, RZ gates, and the like; two or more bit quantum logic gates, such as CNOT gates, CR gates, CZ gates, iSWAP gates, toffoli gates, and the like. Quantum logic gates are typically represented using unitary matrices, which are not only in matrix form, but also an operation and transformation. The effect of a general quantum logic gate on a quantum state is calculated by multiplying the unitary matrix by the matrix corresponding to the right vector of the quantum state.
Referring to fig. 2, fig. 2 is a flow chart of a method for preparing a system experimental state based on spin symmetry and equivalent particle characteristics according to an embodiment of the present application, which may include the following steps:
s21, determining a system and the number of orbitals and electrons of the system.
Wherein the system is a chemical molecular model to be simulated. The chemical molecular model may be considered as a molecular structure modeling in which a user wants to calculate ground state energy, including, for example, the type of atoms, the number of atoms, the atomic coordinates, the charge, the spin severity, and the like, constituting the chemical molecule.
The architecture may be determined by, but is not limited to, the following manner, and a user may enter chemical molecular model information on a computer terminal that the user wants to simulate. For example, a user clicks on the computer's quantum chemistry simulation application software, which can display on the application interface the chemical molecular model options to be simulated, such as hydrogen molecular model, oxygen molecular model, and so forth. The user clicks the chemical molecular model option which wants to simulate, and the quantum chemistry simulation application can determine the chemical molecular model. When the chemical molecular model is determined, the number of electrons and the number of electron orbitals of the chemical molecular model can be determined.
After the system is determined, the number of orbits and the number of electrons of the system can be determined, and at this time, step S22 is performed.
S22, determining the number of excitation terms included in the cluster operator of the Fermi form of the system according to the number of orbitals and the number of electrons of the system based on the spin symmetry and the equivalent particle characteristics.
Specifically, based on the spin symmetry and the equivalent particle characteristics, determining the number of excitation terms and the coefficients corresponding to the excitation terms included in the cluster operator of the fermi form of the system according to the number of orbits and the number of electrons of the system may include the following steps:
s221, acquiring the Hartree-Fock state of the system according to the track number and the electron number of the system.
For example, for the Hartree-Fock (hart-Fock) state of a hydrogen molecule containing two electrons of four single electron spin molecular orbitals, it is represented by quantum state |0011>, i.e., one quantum bit represents one spin molecular orbital, 0 represents an empty orbital, and 1 represents an occupied orbital. By applying a NOT gate to the corresponding bit, respectively, |0000> can be initialized to |0011> in the quantum wire. For any N-electron system containing M spin molecular orbitals, the corresponding Hartree-Fock states can be similarly represented.
S222, determining the number of excitation terms and coefficients corresponding to the excitation terms, which are included by the cluster operators of the fermi form of the system, based on the spin symmetry, the equivalent particle characteristics and the Hartree-Fock state of the system according to a pre-selected design mode.
Exemplary, the proposed modes include: UCC (Unitary Coupled Cluster, unitary coupling cluster operator) and the like, and UCC can be specifically classified into single-excitation coupling clusters UCCs, single-double-excitation coupling clusters UCCSD.
Correspondingly, for UCCS and UCCSD, the quantum circuits to be corresponding are the same, for example, as shown in fig. 3. Fig. 3 is a schematic diagram of a quantum circuit structure corresponding to a proposed mode according to an embodiment of the present application, where the quantum circuit shown in fig. 3 is a quantum circuit of 4 quantum bits q0, q1, q2, q3, and X -π/2 、X π/2 X gate and Y gate with parameters of-pi/2 and pi/2 respectively are the same, and the icon and the solid connection line represent CNOT gate and Z θ A Z gate with parameter θ. The displayed design principle may include: the proposed formula may be, for example, a matrix operator U (θ) corresponding to the quantum wire. For UCC, the corresponding proposed formula is:
wherein, the liquid crystal display device comprises a liquid crystal display device,i.e. is to be set up, P i For generating the element, if the electronic cluster operator t=t in UCC 1 This is called UCCS; if the cluster operator t=t in UCC 1 +T 2 This is called UCCSD, where T 1 For single particle excitation operators, T 2 The operator is excited for double particles. More specifically, in practical applications, T is understood to be a cluster operator in the fermi form. The physical definition is as follows:
in the two formulas described above, the first and second compounds,and->To create an operator->And->Is annihilation operator; />And->The coefficients are typically referred to as the amplitudes of the corresponding operators.
When the design mode is a single excitation coupling cluster, the cluster operator of the Fermi form of the system only comprises a single excitation term number, and on the basis, the single excitation term number is determined to be an excitation term corresponding to each electron in the system from the original spin direction orbit to other orbits with the same spin direction based on the spin symmetry and the Hartree-Fock state. The orbits of the system include both spin-down orbits and spin-up orbits. That is, based on spin symmetry, if the original spin-direction orbit in which an electron is located is spin-up orbit, only excitation of the electron to other spin-up orbits is considered. If the original spin-direction orbit in which an electron is located is the spin-down orbit, then only the electron is considered to be excited to the other spin-down orbits. Based on the above, further, based on the equivalent particle characteristics, the clusters corresponding to the two single-excitation terms with the same excitation probability in the determined single-excitation term numbers are combined, and the combined single-excitation term coefficient is twice that of the single-excitation term coefficient before combination.
When the pre-selected design mode is a single-double excitation coupling cluster, the cluster operator of the Fermi form of the system only comprises a single-excitation term number and a double-excitation term number, and further, based on the spin symmetry and the Hartree-Fock state, the single-excitation term number is determined to be an excitation term corresponding to each electron in the system from the original spin direction orbit to other orbits with the same spin direction; and determining the number of the double excitation terms as excitation terms from the original spin direction orbits where each two electrons are positioned to other two orbits with the same corresponding spin direction in the system. On the basis, further, based on the equivalent particle characteristics, combining the cluster operators corresponding to two single-excitation items with the same excitation probability in the determined single-excitation item number, wherein the combined single-excitation item coefficient is twice that of the single-excitation item coefficient before combination; and merging the cluster operators corresponding to the two double-excitation terms with the same excitation probability in the determined double-excitation term number, wherein the merged double-excitation term coefficient is twice the double-excitation term coefficient before merging.
Taking a hydrogen molecule as an example, for |0011 describing a hydrogen molecule > Hartree-Fock In this state, T is the cluster operator of the Fermi form of the hydrogen molecule. Referring to fig. 4, fig. 4 is a schematic diagram of a hydrogen molecular orbital provided in an embodiment of the present application. As shown in fig. 4, for a hydrogen molecule, the 1Sa orbitals of the hydrogen atom of a spin down and spin up are conveniently represented by q0, q1 qubits, and the 1Sb orbitals of the hydrogen atom of b spin down and spin up are represented by q2, q3 qubits, respectively.
As shown in fig. 4, assuming that two electrons of a hydrogen molecule are located on the two orbitals of q0 and q1, respectively, if one electron is located on the spin orbit represented by the quantum state |1>, and the spin orbit is empty, the Hartree-Fock state of the hydrogen molecule can be represented as |0011>.
When an electron on q0 is excited onto q2, that is, the electron is "annihilated" from q0 and then "generated" on q2, it can be expressed in terms of the fermi operator:
wherein t is 20 As the coefficient of the light-emitting diode,to create an operator a 0 Is annihilation operator.
When an electron on q0 is excited onto q3, that is, the electron is "annihilated" from q0 and then "generated" on q3, it can be expressed in terms of the fermi operator:
wherein t is 30 As the coefficient of the light-emitting diode,to create an operator a 0 Is annihilation operator.
When an electron on q1 is excited onto q2, that is, the electron is "annihilated" from q1 and then "generated" on q2, it can be expressed in terms of the fermi operator:
wherein t is 21 As the coefficient of the light-emitting diode,to create an operator a 1 Is annihilation operator.
When an electron on q1 is excited onto q3, that is, the electron is "annihilated" from q1 and then "generated" on q3, it can be expressed in terms of the fermi operator:
wherein t is 31 As the coefficient of the light-emitting diode,to create an operator a 1 Is annihilation operator.
When electrons on q0, q1 are simultaneously excited to q2, q3, that is, the electrons are "annihilated" from q0, q1 and then "generated" on q2, q3, they can be expressed as:
wherein t is 3210 As the coefficient of the light-emitting diode,to create an operator a 1 、a 0 Is annihilation operator.
For |0011 describing Hydrogen molecules> Hartree-Fock In the state, T is the cluster operator H of the Fermi form of the hydrogen molecule u ：
Wherein T is 1 Is a single particle excitation operator, T 2 Is a double particle excitation operator.
When the proposed scheme is a unixcited coupled cluster, the cluster operator of the fermi form of the system includes the number of unixcited terms. I.e. for |0011 describing a hydrogen molecule> Hartree-Fock In the state, the prior art does not consider spin symmetry and equivalent particle characteristics:
the inventor of the present application combines spin symmetry, namely a transition rule, and only needs to consider two transition states of excitation of electrons on q0 to q2 and excitation of electrons on q1 to q3 when the design mode is a single excitation coupling cluster. Thus, in this application, based on spin symmetry, when the proposed approach is a single excitation coupled cluster:
That is, when the proposed method is a single excitation coupled cluster, the number of excitation terms included in the cluster operator of the fermi form of the hydrogen molecule used for calculation is only two after considering the spin symmetry, whereas the number of excitation terms included in the cluster operator of the fermi form of the hydrogen molecule used for calculation in the prior art is four.
Next, consider the case of equivalent particle characteristics. It is known that in the microscopic world, isotactic particles are indistinguishable, which is in stark contrast to our classical mechanics. In classical mechanics, even though the intrinsic properties of the individual objects are the same, we can still distinguish them according to their trajectory of motion, numbering them: ball 1, ball 2, etc. However, in quantum mechanics, the wave functions are dispersed in space, that is, the wave functions of particles in the same region overlap, and the particles cannot be identified by numbering without an exact orbit concept. Multiparticulate systems of the same type of particle composition are known as isotactic particle systems. However, for the convenience of calculation, we manually numbered the numbers, but the numbers are not practically realized. That is, the probability of a particle transitioning between two energy levels is not dependent on the particular trajectory in which it is located, but rather on the energy difference of the energy levels between the two energy levels, where the respective trajectories at the same energy level are equivalent.
Taking hydrogen molecules as an example, equivalent particle characteristics are: the electron excitation on q0 to q2 is equivalent to the electron excitation on q1 to q3, and the electron excitation on q0 to q3 is equivalent to the electron excitation on q1 to q 2. We can obtain: t is t 20 ＝t 31 And t 30 ＝t 21 . That is, as long as the energy levels before and after excitation are the same, the same process can be regarded as having the same excitation probability, the amplitude values of cluster operators corresponding to the excitation terms are also the same, and the combination can be performed, thereby reducing the number of parameters, wherein,the cluster operator amplitude value corresponding to the combined excitation term is approximately twice the original cluster operator amplitude value.
The application combines the equivalent particle characteristics, when the design mode is a single excitation coupling cluster:
wherein t' 20 At t 20 Approximately twice, t' 30 At t 30 Approximately twice as many as (a), it can be considered that:
t′ 20 ＝2t 20
t′ 30 ＝2t 30
next, spin symmetry and equivalent particle properties are combined simultaneously. In the case of spin symmetry, when the proposed mode is a uniexcited coupled cluster, t=t 1 ＝H 1 +H 4 Combining with the equivalent particle characteristics, the excitation of electrons on q0 to q2 is equivalent to the excitation of electrons on q1 to q3, H 1 And H 4 The same process can be regarded as the same process, the same excitation probability exists, the amplitude values of cluster operators corresponding to the excitation terms are the same, and the combination can be performed.
Thus, the present application combines spin symmetry and equivalent particle characteristics when the proposed approach is a single excitation coupled cluster:
wherein t' 20 At t 20 Approximately twice as many as (a), it can be considered that:
t′ 20 ＝2t 20
that is, when the proposed mode is a single excitation coupled cluster, the present application includes only one term of the number of excitation terms of the fermi form cluster operator of the hydrogen molecule used for calculation, while the number of excitation terms of the fermi form cluster operator of the hydrogen molecule used for calculation in the prior art is four terms, taking into consideration the spin symmetry and the equivalent particle characteristics.
When the proposed scheme is a single-double excitation coupled cluster, the cluster operator of the fermi form of the system includes the number of single-excitation terms and the number of double-excitation terms, i.e., |0011 for describing a hydrogen molecule> Hartree-Fock State, irrespective of spin symmetry and equivalent particle characteristics:
the application combines spin symmetry and equivalent particle characteristics, when the design mode is a single-double excitation coupling cluster:
wherein t' 20 At t 20 Approximately twice as many as (a), it can be considered that:
t′ 20 ＝2t 20
that is, when the present application is designed as a single-double excitation coupled cluster in combination with spin symmetry and equivalent particle characteristics, the number of excitation terms included in the fermi form of the cluster operator of the hydrogen molecule used in the calculation of the present application is only two, while the number of excitation terms included in the fermi form of the hydrogen molecule used in the calculation of the prior art is five.
It should be emphasized that the determination of the number of excitation terms and the coefficients corresponding to the excitation terms by combining the equivalent particle characteristics is equally effective for the double excitation process, and cannot be revealed due to the simple hydrogen molecular system. However, as long as the energy levels before and after excitation are the same, the same process can be considered as the same process, the excitation probability is the same, the amplitude values of the cluster operators corresponding to the excitation terms are the same, and the combination can be performed, so that the number of parameters is reduced, wherein the amplitude value of the cluster operators corresponding to the combined excitation terms is approximately twice the amplitude value of the original cluster operators.
In addition, the above proposed scheme is merely an example, and does not limit the present invention, and for example, the scheme may also include HE (Hardware Efficient ), SP (Symmetry Preserved, symmetrical hold), and the like.
After determining the number of excitation terms and the coefficients corresponding to the excitation terms included in the cluster operator of the fermi form of the system, step S23 is performed.
S23, calculating the cluster operator of the Fermi sub-form of the system according to the number of the excitation terms and the coefficients corresponding to the excitation terms.
In step S22, a formula of a cluster operator of the fermi form corresponding to the hydrogen molecule has been given, and similarly, for other systems, after determining the number of excitation terms and coefficients corresponding to the excitation terms included in the cluster operator of the fermi form, the cluster operator of the fermi form of the system can be calculated according to the formula corresponding to the system.
After computing the clustering operators of the fermi sub-form of the system, step S24 is performed.
S24, solving the experimental state of the system based on the cluster operator of the Fermi form of the system.
The experimental state of the system is an important intermediate parameter in the process of calculating the ground state energy of the system. For any one of the test states |ψ>When the Hamiltonian H of a certain system is used for acting on the system, the average energy E of the system in the state can be obtained, and the average energy is larger than or equal to the ground state energy E of the system 0 The expression is as follows:
it can be seen from the expression that by continuously adjusting the test state, if the adjusted test state |ψ>Is the ground state |psi of the system 0 >When the equality sign in the inequality is established, the ground state energy E of the system can be obtained 0 。
Optionally, solving the experimental state of the system based on the cluster operator of the fermi sub-form of the system may include the steps of:
s241, converting the Klebsiella form cluster operators of the Fermi sub-form of the system into the Klebsiella form cluster operators of the Brix operator form according to a pre-selected mapping mode.
The mapping manner may include: jordan-Wigner transform (J-W transform), party transform, bravyi-Kitaev transform (B-K transform), MSP (Multilayer Segmented Parity; multi-layer chunking universe) transform, and so forth.
As will be appreciated by those skilled in the art, the mapping principles for each mapping scheme may include: a state mapping principle and an operator mapping principle.
For example, for the J-W transform, the displayed state map is:
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the computational state of the qubit,/->Representing a transformation matrix->Representing the occupancy state of the fermi subsystem. The operator map displayed is:
/>
wherein, the liquid crystal display device comprises a liquid crystal display device,representing the lifting operator, j representing the qubit sequence number, P representing the universe set, Z P(j) Represents a set of brix matrices acting on qubits belonging to the universe set P, X represents a brix matrix, and Y represents a briy matrix.
Equally, the operator map may also be displayed as:
wherein, the liquid crystal display device comprises a liquid crystal display device,representation generating operator, a j Representing annihilation operator->And a j Collectively referred to as the lifting operators of the fermi subsystem,representing the production operator/annihilation operator on a qubit,>represents a space operator, and n represents a qubit number.
The state map and operator map of the other transforms are displayed in the same manner as the J-W transform.
Wherein the Fermi-form cluster operators are transformed into the Brix-form cluster operators according to a pre-selected mapping mode. For example, for UCCS designT is a cluster operator in the form of a Fermi sub-form, which needs to be transformed into a Paulownian form so as to generate a unitary operator according to the Paulownian, and the unitary operator is the basis for constructing a specific quantum circuit to be correspondingly designed.
After converting the cluster operators in the fermi sub-form into the cluster operators in the form of the brix operators represented by the brix operators, step S242 is performed.
S242, decomposing the cluster operators in the form of the bubble operator into corresponding unitary operator forms and evolving to obtain evolved quantum states; wherein the quantum state after evolution is a test state of the system.
Optionally, decomposing the cluster operator in the form of the bubble operator into a corresponding unitary operator form and evolving to obtain an evolved quantum state, which may include the following steps:
s2421, constructing a quantum simulation circuit based on the unitary operators corresponding to the cluster operators in the form of the bubble operator after decomposition.
S2422, performing simulated evolution according to the quantum simulation circuit to obtain an evolved quantum state.
Next, please refer to fig. 5-9. Assuming that the Fermi sub-cluster operator containing five sub-items is J-W transformed, the cluster operator T in the form of a Brix operator is as follows:
first, calculate H 1 The corresponding unitary operator:
FIG. 5 is a diagram of H provided in an embodiment of the present application 1 A corresponding quantum circuit schematic. As shown in fig. 5, by H 1 The corresponding unitary operator can be seen to add RZ (2. Theta. To q0 1 ) The door can obtain H 1 A corresponding quantum wire.
Next, calculate H 2 The corresponding unitary operator:
FIG. 6 is a diagram of H provided in an embodiment of the present application 1 And H 2 A corresponding quantum circuit schematic. As shown in fig. 6, by H 2 The corresponding unitary operator can know that q0 is used as a control bit, q1 is used as a target bit, and a CNOT gate is added; then, RZ (2. Theta. Was added to q1 2 ) A door; then, q0 bit is used as a control bit, q1 is used as a target bit, and a CNOT gate is added to obtain H 2 A corresponding quantum wire.
Next, calculate H 3 The corresponding unitary operator:
FIG. 7 is a diagram of H provided in an embodiment of the present application 1 、H 2 And H 3 A corresponding quantum circuit schematic. As shown in fig. 7, by H 3 The corresponding unitary operator can know that q0 is used as a control bit, q1 is used as a target bit, q1 is used as a control bit, q2 is used as a target bit, and two CNOT gates are added in sequence; then, RZ (2, 2. Theta. Is added to q2 3 ) A door; then, q0 bit is used as a control bit, q1 is used as a target bit, and a CNOT gate is added to obtain H 3 A corresponding quantum wire.
Next, calculate H 4 The corresponding unitary operator:
FIG. 8 is a diagram of H provided in an embodiment of the present application 1 、H 2 、H 3 And H 4 A corresponding quantum circuit schematic. As shown in fig. 8, by H 4 The corresponding unitary operator can know that a Hadamard gate needs to be added on q 0; then q0 is used as a control bit, q1 is used as a target bit, and a first CNOT gate is added; next, RZ (2. Theta. Was added to q1 4 ) A door; then, q0 is taken as a control bit, q1 is taken as a target bit, and a second CNOT gate is added; finally, adding a Hadamard gate to q0 to obtain H 4 A corresponding quantum wire.
Next, calculate H 5 The corresponding unitary operator:
fig. 9 is a diagram of H provided in an embodiment of the present application 1 、H 2 、H 3 、H 4 And H 5 A corresponding quantum circuit schematic. As shown in fig. 9, by H 5 The corresponding unitary operator can be found to require the addition of q0 toA door; then q0 is used as a control bit, q1 is used as a target bit, and a first CNOT gate is added; next, RZ (2. Theta. Was added to q1 5 ) A door; then, q0 is taken as a control bit, q1 is taken as a target bit, and a second CNOT gate is added; finally, add +.>The door can obtain the simulation H 5 A corresponding quantum wire. That is, FIG. 9 includes H 1 、H 2 、H 3 、H 4 And H 5 A corresponding quantum wire schematic, i.e., a quantum wire corresponding to H is shown in fig. 9.
In combination with equivalent particle characteristics, let H be 1 Equivalent to H 4 Calculate the merge H 1 And H 4 The following unitary operator should be:
θ′ 1 ＝2θ 1
that is, combine H 1 And H 4 The quantum circuit corresponding to the unitary operator is similar to the quantum circuit schematic diagram shown in fig. 5, except that θ 1 Change to theta' 1 。
Fig. 5-9 illustrate how a clustering operator in the form of a fermi sub-form containing five sub-items constructs a quantum wire. For |0011 describing Hydrogen molecules > Hartree-Fock In a state, under the conditions that the preset mode is UCCSD, the mapping mode is J-W conversion and the rotation symmetry and the equivalent particle characteristics are not considered, the Fermi-form cluster operator also comprises five sub-items, namely when a quantum circuit is constructed, the five sub-items of the Fermi-form cluster operator need to be converted into the Paulori operator form and decomposed into corresponding unitary operatorsForm of the invention. Then, the quantum wires corresponding to the five sub-items are constructed according to the time sequence. And combining quantum circuits corresponding to the five sub-items to obtain the quantum analog circuit. And finally, carrying out simulated evolution according to the quantum simulation circuit to obtain an evolved quantum state.
The present application, however, is directed to |0011 describing hydrogen molecules due to consideration of spin symmetry and equivalent particle characteristics> Hartree-Fock And under the condition that the proposed mode is a single-double excitation coupling cluster and the mapping mode is J-W conversion, the cluster operator in the fermi sub-form has only two sub-items. When constructing the quantum circuit, only two sub-items are converted into the form of a bubble operator and decomposed into the form of a corresponding unitary operator. Then, the quantum wires corresponding to the two sub-items are constructed according to the time sequence. And combining the quantum circuits corresponding to the two sub-items to obtain the quantum analog circuit. And finally, carrying out simulated evolution according to the quantum simulation circuit to obtain an evolved quantum state.
In the process of preparing the experimental state of the system, the method calculates the Fermi form cluster operator of the system, and the self-rotation symmetry and the equivalent particle characteristics are considered, so that the number of the excitation terms required to be calculated in the Fermi form cluster operator is smaller than the number of the excitation terms without the self-rotation symmetry in the prior art, the complexity of the system is reduced, the calculated amount is reduced when the experimental state of the system is solved, the technical problem that complex molecules are difficult to simulate in the prior art is solved, the calculation resources are saved, the calculation of the energy of the subsequent system is facilitated, and the simulation efficiency of the complex molecules is improved.
In practical application, for any one of the test states |ψ>When it is acted on by the Hamiltonian of a certain system (such as multi-electron system), the average energy E of the system in this state can be obtained, which is greater than or equal to the energy E of the system 0 . Continuously adjusting the test state until the test state |psi>Is the ground state |psi of the system 0 >When the energy E of the system is correspondingly obtained 0 。
Therefore, further, after the system experimental state |ψ > is prepared by the method for calculating the system experimental state provided by the application, the ground state energy of the system can be solved. For example, first, the average energy of the system at the experimental state |ψ > is calculated; then, it is judged whether or not the average energy of the system in the experimental state |ψ > can be regarded as the ground state energy of the system. If yes, the ground state energy of the system can be obtained; otherwise, updating the test state and returning to the step of calculating the average energy of the system in the test state.
According to the method, when the Fermi form cluster operator of the system is calculated, the spin symmetry and the equivalent particle characteristics are considered, the number of excitation terms needed to be calculated in the Fermi form cluster operator is smaller than that needed when the spin symmetry is not considered in the prior art, the complexity of the system is reduced, the calculated amount is reduced when the energy of the system is solved, the technical problem that complex molecules are difficult to simulate in the prior art is solved, the calculation resources are saved, and the simulation efficiency of the complex molecules is improved.
Referring to fig. 10, fig. 10 is a schematic structural diagram of an apparatus for preparing a system experimental state based on spin symmetry and equivalent particle characteristics according to an embodiment of the present invention, corresponding to the flow shown in fig. 2, the apparatus 110 for preparing a system experimental state based on spin symmetry and equivalent particle characteristics includes:
a first determining module 111, configured to determine a system and a track number and an electron number of the system;
a second determining module 112, configured to determine, based on the spin symmetry and the equivalent particle characteristics, the number of excitation terms and coefficients corresponding to the excitation terms included in the cluster operator of the fermi form of the system according to the number of orbitals and the number of electrons of the system;
A calculating module 113, configured to calculate a cluster operator in the fermi form of the system according to the number of excitation terms and coefficients corresponding to the excitation terms;
a solution module 114 for determining cluster operators based on the fermi sub-form of the system, and solving the experimental state of the system.
Optionally, the second determining module 112 includes:
the acquisition unit is used for acquiring the Hartree-Fock state of the system according to the track number and the electron number of the system;
and the determining unit is used for determining the number of the excitation terms and the coefficients corresponding to the excitation terms, which are included by the cluster operators of the fermi form of the system, based on the spin symmetry, the equivalent particle characteristics and the Hartree-Fock state of the system according to the pre-selected design mode.
Optionally, the determining unit is further configured to: when the proposed mode is a single excitation coupling cluster, determining that the cluster operator of the Fermi form of the system only comprises a single excitation term number; based on spin symmetry and Hartree-Fock state, determining the number of the single excitation terms as excitation terms corresponding to the fact that each electron in the system is excited from the original spin direction orbit to other orbits with the same spin direction; and merging the cluster operators corresponding to the two single-excitation items with the same excitation probability in the determined single-excitation item number based on the equivalent particle characteristics, wherein the single-excitation item coefficient after merging is twice the single-excitation item coefficient before merging.
Optionally, the determining unit is further configured to: when the pre-selected design mode is a single-double excitation coupling cluster, confirming that the cluster operator of the Fermi form of the system only comprises a single-excitation item number and a double-excitation item number; based on spin symmetry and Hartree-Fock state, determining the number of the single excitation terms as excitation terms corresponding to the fact that each electron in the system is excited from the original spin direction orbit to other orbits with the same spin direction; determining the number of the double excitation terms as excitation terms from the original spin direction orbits where each two electrons are located to other two orbits with the same corresponding spin direction; combining cluster operators corresponding to two single-excitation items with the same excitation probability in the determined single-excitation item number based on the equivalent particle characteristics, wherein the combined single-excitation item coefficient is twice that of the single-excitation item coefficient before combination; and merging the cluster operators corresponding to the two double-excitation terms with the same excitation probability in the determined double-excitation term number, wherein the merged double-excitation term coefficient is twice the double-excitation term coefficient before merging.
Optionally, the second determining module 112 further includes:
A transformation unit for transforming the cluster operators in the form of fermi sub-forms of the hierarchy into the cluster operators in the form of bubble sharp operators according to a pre-selected mapping scheme;
the evolution unit is used for decomposing the cluster operators in the form of the bubble operator into corresponding unitary operator forms and evolving to obtain evolved quantum states; wherein the quantum state after evolution is a test state of the system.
Optionally, the evolution unit is further configured to: constructing a quantum simulation circuit based on the unitary operators corresponding to the cluster operators in the form of the bubble operator after decomposition; and performing simulated evolution according to the quantum simulation circuit to obtain an evolved quantum state.
Optionally, the mapping mode is one of Jordan-Wigner transformation, party transformation, bravyi-Kitaev transformation and segmentParty transformation.
In addition, the technical effects of the apparatus 110 for preparing a system experimental state based on spin symmetry and equivalent particle characteristics may refer to the technical effects of the method for calculating a system experimental state shown in fig. 2, and will not be described herein.
The embodiment of the invention also provides a storage medium, in which a computer program is stored, wherein the computer program is configured to perform the steps of any of the method embodiments described above when run.
Specifically, in the present embodiment, the above-described storage medium may be configured to store a computer program for executing the steps of:
s1, determining a system, and determining the number of orbits and the number of electrons of the system;
s2, determining the number of excitation terms and coefficients corresponding to the excitation terms, which are included by a cluster operator of the Fermi form of the system, according to the number of orbits and the number of electrons of the system based on the spin symmetry and the equivalent particle characteristics;
s3, calculating a cluster operator of the Fermi form of the system according to the number of the excitation terms and the coefficients corresponding to the excitation terms;
s4, solving the experimental state of the system based on the cluster operator of the Fermi form of the system.
Specifically, in the present embodiment, the storage medium may include, but is not limited to: a usb disk, a Read-only memory (ROM), a random access memory (Random Access Memory, RAM), a removable hard disk, a magnetic disk, or an optical disk, or other various media capable of storing a computer program.
The present invention also provides an electronic device comprising a memory having a computer program stored therein and a processor arranged to run the computer program to perform the steps of any of the method embodiments described above.
Specifically, the electronic apparatus may further include a transmission device and an input/output device, where the transmission device is connected to the processor, and the input/output device is connected to the processor.
Specifically, in the present embodiment, the above-described processor may be configured to execute the following steps by a computer program:
s1, determining a system, and determining the number of orbits and the number of electrons of the system;
s2, determining the number of excitation terms and coefficients corresponding to the excitation terms, which are included by a cluster operator of the Fermi form of the system, according to the number of orbits and the number of electrons of the system based on the spin symmetry and the equivalent particle characteristics;
s3, calculating a cluster operator of the Fermi form of the system according to the number of the excitation terms and the coefficients corresponding to the excitation terms;
s4, solving the experimental state of the system based on the cluster operator of the Fermi form of the system.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.
The foregoing describes specific embodiments of the present disclosure. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
The terminology used in the one or more embodiments of the specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the one or more embodiments of the specification. As used in this specification, one or more embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.
It should be understood that although the terms first, second, third, etc. may be used in one or more embodiments of the present description to describe various information, these information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of one or more embodiments of the present description. The word "if" as used herein may be interpreted as "at … …" or "at … …" or "responsive to a determination", depending on the context. The foregoing description of the preferred embodiment(s) is (are) merely intended to illustrate the embodiment(s) of the present invention, and it is not intended to limit the embodiment(s) of the present invention to the particular embodiment(s) described.
The foregoing detailed description of the construction, features and advantages of the present application will be presented in terms of embodiments illustrated in the drawings, wherein the foregoing description is merely illustrative of preferred embodiments of the application, and the scope of the application is not intended to be limited to the details of construction and the embodiments of the application, as long as they are embodied in the principles of the present application, or as long as they are modified and practiced in the equivalent manners of use without departing from the spirit of the invention as defined by the description and the drawings.
Claims (10)
1. A method for preparing a system test state based on spin symmetry and equivalent particle characteristics, comprising:
determining a system and the number of orbits and electrons of the system, wherein the system is a chemical molecular model to be simulated;
determining the number of excitation terms and coefficients corresponding to the excitation terms included by the cluster operators of the fermi sub-form of the system according to the number of orbits and the number of electrons of the system based on the spin symmetry and the equivalent particle characteristics;
calculating a cluster operator of the Fermi form of the system according to the number of the excitation terms and the coefficients corresponding to the excitation terms;
based on the cluster operators of the fermi form of the system, the experimental state of the system is solved.
2. The method of claim 1, wherein the determining the number of excitation terms and coefficients corresponding to the excitation terms included in the cluster operator of the fermi sub-form of the system based on the spin symmetry and the equivalent particle characteristics from the number of orbitals and the number of electrons of the system comprises:
Acquiring a Hartree-Fock state of the system according to the track number and the electron number of the system;
according to a pre-selected design mode, the number of excitation terms and coefficients corresponding to the excitation terms included in the cluster operator of the Fermi form of the system are determined based on spin symmetry, equivalent particle characteristics and the Hartree-Fock state of the system.
3. The method of claim 2, wherein the determining the number of excitation terms included in the cluster operator of the fermi sub-form of the system based on spin symmetry, equivalent particle characteristics, and Hartree-Fock states of the system according to the pre-selected design approach comprises:
when the proposed mode is a single excitation coupling cluster, confirming that the cluster operator of the Fermi form of the system only comprises a single excitation item number;
based on spin symmetry and Hartree-Fock state, determining the number of the single excitation terms as excitation terms corresponding to the fact that each electron in the system is excited from the original spin direction orbit to other orbits with the same spin direction;
and merging the cluster operators corresponding to the two single-excitation items with the same excitation probability in the determined single-excitation item number based on the equivalent particle characteristics, wherein the single-excitation item coefficient after merging is twice the single-excitation item coefficient before merging.
4. The method of claim 2, wherein the determining the number of excitation terms included in the cluster operator of the fermi sub-form of the system based on spin symmetry, equivalent particle characteristics, and Hartree-Fock states of the system according to the pre-selected design approach comprises:
when the pre-selected design mode is a single-double excitation coupling cluster, confirming that the cluster operator of the Fermi form of the system only comprises a single-excitation item number and a double-excitation item number;
based on spin symmetry and Hartree-Fock state, determining the number of the single excitation terms as excitation terms corresponding to the fact that each electron in the system is excited from the original spin direction orbit to other orbits with the same spin direction; determining the number of the double excitation terms as excitation terms from the original spin direction orbits where each two electrons are located to other two orbits with the same corresponding spin direction;
combining cluster operators corresponding to two single-excitation items with the same excitation probability in the determined single-excitation item number based on the equivalent particle characteristics, wherein the combined single-excitation item coefficient is twice that of the single-excitation item coefficient before combination; and merging the cluster operators corresponding to the two double-excitation terms with the same excitation probability in the determined double-excitation term number, wherein the merged double-excitation term coefficient is twice the double-excitation term coefficient before merging.
5. The method of claim 2, wherein the solving the experimental state of the system based on the cluster operator of the fermi sub-form of the system comprises:
transforming the cluster operators in the form of fermi sub-forms of the system into cluster operators in the form of bubble sharp operators according to a pre-selected mapping mode;
decomposing the cluster operators in the form of the bubble operator into corresponding unitary operator forms and evolving to obtain evolved quantum states; wherein the quantum state after evolution is a test state of the system.
6. The method of claim 5, wherein decomposing the cluster operator in the form of a berlite operator into a corresponding unitary operator form and evolving to obtain an evolved quantum state, comprises:
constructing a quantum simulation circuit based on the unitary operators corresponding to the cluster operators in the form of the bubble operator after decomposition;
and performing simulated evolution according to the quantum simulation circuit to obtain an evolved quantum state.
7. The method of claim 5 or 6, wherein the mapping mode is one of Jordan-Wigner transformation, party transformation, bravyi-Kitaev transformation, and segmentParty transformation.
8. An apparatus for preparing a system test state based on spin symmetry and equivalent particle characteristics, comprising:
The first determining module is used for determining a system and the number of orbits and electrons of the system, wherein the system is a chemical molecular model to be simulated;
the second determining module is used for determining the number of excitation terms and coefficients corresponding to the excitation terms, which are included by the cluster operators in the fermi form of the system, according to the orbit number and the electron number of the system based on the spin symmetry and the equivalent particle characteristics;
the calculation module is used for calculating the cluster operators of the fermi sub-form of the system according to the number of the excitation terms and the coefficients corresponding to the excitation terms;
and the solving module is used for determining cluster operators based on the Fermi form of the system and solving the experimental state of the system.
9. An electronic device, comprising:
a processor;
a memory for storing processor-executable instructions;
wherein the processor is configured to implement the method of any of claims 1-7 by executing the executable instructions.
10. A computer storage medium having stored thereon computer instructions which, when executed by a processor, implement the steps of the method of any of claims 1-7.
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