CN115358407A

CN115358407A - Approximate quantum compiling method and system based on tensor network and electronic equipment

Info

Publication number: CN115358407A
Application number: CN202210980282.0A
Authority: CN
Inventors: 周祥臻
Original assignee: Beijing Zhongke Arc Quantum Software Technology Co ltd
Current assignee: Beijing Zhongke Arc Quantum Software Technology Co ltd
Priority date: 2022-08-16
Filing date: 2022-08-16
Publication date: 2022-11-18
Anticipated expiration: 2042-08-16
Also published as: CN115358407B

Abstract

The invention relates to the technical field of quantum compilation, in particular to an approximate quantum compilation method, an approximate quantum compilation system and electronic equipment based on a tensor network, wherein the method comprises the following steps: dividing the quantum circuit to be compiled into a plurality of sub-circuits, wherein the quantum bit of each sub-circuit is not more than the maximum value of the number of preset quantum bits; on the basis of a tensor network theory, compiling each sub-line into a new sub-line only containing basic quantum operation, and enabling any sub-line to be approximately equivalent to the new sub-line corresponding to the sub-line; and combining all the new sub-circuits to obtain a new quantum circuit, and determining the new quantum circuit as a final compiling result. By utilizing the cutting characteristic of tensor, in line division, compared with a scheme expressed by a traditional unitary matrix, fewer sub-lines can be generated, and the number of quantum operations contained in each sub-line is more than that of the scheme expressed by the traditional unitary matrix, so that the coding effect is improved.

Description

Approximate quantum compiling method and system based on tensor network and electronic equipment

Technical Field

The invention relates to the technical field of quantum compiling, in particular to a tensor network-based approximate quantum compiling method, a tensor network-based approximate quantum compiling system and electronic equipment.

Background

A quantum circuit is a common representation of a quantum process, which is composed of quantum bits and a series of quantum operations, and unitary matrices are a basic description of quantum operations in quantum computing, and similarly, a quantum circuit can be described by all unitary matrices that contain the corresponding quantum operations. However, a quantum computer can only perform a specific basic operation, and therefore, before executing a quantum wire in the quantum computer, it is necessary to decompose all general quantum operations in the wire into a series of basic operations, and the quantum wires before and after decomposition are required to be approximately equal in function (i.e. the unitary matrix descriptions of the quantum wires before and after decomposition are approximately equal), which is called approximate quantum coding in this patent.

The performance of a quantum compiler can be measured by the number of basic operations of the quantum wire it outputs, and the smaller the number of basic operations, the better the performance of the quantum compiler. The conventional quantum coding scheme based on unitary matrix description can only process quantum wires containing very small number of quantum bits (usually not more than 4), so when coding a quantum wire containing more quantum bits, the input quantum wire needs to be cut into a plurality of sub-quantum wires containing only very few quantum bits, then each sub-quantum wire needs to be separately coded, and finally, the plurality of coded quantum wires are recombined into a new quantum wire to be output. The above process requires separate compilation of multiple sub-lines, and the performance of the compiler decreases as the number of sub-quantum lines compiled and the number of quantum operations contained in each sub-line increases.

Disclosure of Invention

The invention provides an approximate quantum compiling method, system and electronic equipment based on a tensor network, aiming at the defects of the prior art.

The invention discloses an approximate quantum compiling method based on a tensor network, which has the technical scheme as follows:

dividing the quantum circuit to be compiled into a plurality of sub-circuits, wherein the quantum bit of each sub-circuit is not more than the maximum value of the number of preset quantum bits;

on the basis of a tensor network theory, compiling each sub-line into a new sub-line only containing basic quantum operation, and enabling any sub-line to be approximately equivalent to the new sub-line corresponding to the sub-line;

and combining all the new sub-lines to obtain a new quantum line, and determining the new quantum line as a final compiling result.

The approximate quantum compiling method based on the tensor network has the following beneficial effects:

the quantum operations are expressed by tensor based on a tensor network theory, and by using the cutting characteristic of the tensor, fewer sub-lines can be generated in line division compared with a scheme expressed by a conventional unitary matrix, the number of the quantum operations contained in each sub-line is more than that of the quantum operations expressed by the conventional unitary matrix, and the compiling effect is improved.

The invention discloses an approximate quantum compiling system based on a tensor network, which has the technical scheme as follows:

the device comprises a segmentation module, a compiling module and a combination determining module;

the segmentation module is configured to: dividing the quantum circuit to be compiled into a plurality of sub-circuits, wherein the quantum bit of each sub-circuit is not more than the maximum value of the number of preset quantum bits;

the compiling module is configured to: on the basis of a tensor network theory, compiling each sub-line into a new sub-line only comprising basic quantum operation respectively, and enabling any sub-line to be approximately equivalent to the new sub-line corresponding to the sub-line;

the combination determination module is to: and combining all the new sub-circuits to obtain a new quantum circuit, and determining the new quantum circuit as a final compiling result.

The approximate quantum compiling system based on the tensor network has the following beneficial effects:

based on the tensor network theory, quantum operations are expressed by tensor, and by using the cutting characteristic of the tensor, fewer sub-lines can be generated in line division compared with a scheme expressed by a traditional unitary matrix, the number of quantum operations contained in each sub-line is more than that of the scheme expressed by the traditional unitary matrix, and therefore the coding effect is improved.

A storage medium of the present invention stores instructions, and when the instructions are read by a computer, the instructions cause the computer to execute any one of the tensor network-based approximate quantum compiling methods described above.

An electronic device of the present invention includes a processor and the storage medium, where the processor executes instructions in the storage medium.

Drawings

Fig. 1 is a schematic flowchart of an approximate quantum compiling method based on a tensor network according to an embodiment of the present invention;

FIG. 2 is a drawing

Quantum operation on a qubit

A graph under tensor;

FIG. 3 is a schematic representation of CNOT;

FIG. 4 is a diagram of a qubit

Performing quantum operations

For the qubit

A schematic diagram of performing a CNOT quantum operation;

FIG. 5 is a diagram of an application to qubits

Schematic representation of CNOT quantum manipulation on after cleavage;

FIG. 6 is a schematic diagram of the merging of two tensors into a new tensor;

FIG. 7 is a drawing showing

One of the schematic diagrams of (a);

FIG. 8 is one of the schematic diagrams of qubit sets for two quantum manipulation roles;

FIG. 9 is a schematic view of

A second schematic diagram of (a);

FIG. 10 is a second schematic diagram of a qubit set for two quantum operations;

FIG. 11 is a schematic view of

The third schematic diagram of (a);

FIG. 12 is a schematic diagram of quantum wires and their tensors;

FIG. 13 is a pair tensor

Schematic representation after shrinking;

FIG. 14 is a drawing showing

A schematic diagram of (a);

fig. 15 is a schematic structural diagram of an approximate quantum compiler system based on a tensor network according to an embodiment of the present invention.

Detailed Description

As shown in fig. 1, an approximate quantum compiling method based on a tensor network according to an embodiment of the present invention includes the following steps:

s1, dividing a quantum circuit to be compiled into a plurality of sub-circuits, wherein the quantum bit of each sub-circuit is not more than the maximum value of the number of preset quantum bits;

s2, compiling each sub-line into a new sub-line only containing basic quantum operation based on a tensor network theory, and enabling any sub-line to be approximately equivalent to the new sub-line corresponding to the sub-line;

and S3, combining all the new sub-circuits to obtain a new quantum circuit, and determining the new quantum circuit as a final compiling result.

The specific pseudo code is as follows:

inputting: a quantum wire to be compiled

Medicine for treating diabetesDegree of rotation

Maximum number of qubits in sub-line

。

And (3) outputting: compiled quantum wires

。

1.

；

2. If it is used

Then go to step 6, otherwise then

Taking out the first operation;

3. if it is used

There is a CNOT quantum operation that is cleaved,

entering step 5;

4. call the conventional approximate compiler (prior art) to get

；

5. Will be provided with

Entering the step 2;

6.

merging of all lines in, returning

；

Wherein, the step of dividing the quantum circuit to be compiled into a plurality of sub-circuits comprises the following steps:

s10, initializing a plurality of sub-lines to be constructed, and constructing a mapping relation from quantum bits in the quantum lines to be compiled to the sub-lines to be constructed, wherein each quantum bit in the quantum lines to be compiled corresponds to one sub-line to be constructed;

s11, sequentially extracting the quantum operations in the quantum circuit to be compiled according to the execution sequence of the quantum operations in the quantum circuit to be compiled;

s12, determining the sub-circuit to be constructed corresponding to the quantum operation extracted in the S11 from all the sub-circuits to be constructed according to the mapping relation;

s13, updating the sub-circuit to be constructed corresponding to the quantum operation extracted in the S11 according to the quantum operation of the sub-circuit to be constructed corresponding to the quantum operation extracted in the S11 and the preset maximum value of the number of quantum bits, wherein the specific updating modes are two, specifically:

1) The first updating mode is as follows: adding quantum operation to the sub-line to be constructed corresponding to the quantum operation extracted in the S11;

2) The second updating method is as follows: and after the first updating mode is executed, cutting the added quantum operation.

S14, judging whether any sub-line to be constructed is constructed or not, if yes, determining the sub-line to be constructed as the sub-line, and generating a new sub-line to be constructed;

and S15, updating the mapping relation, returning to execute the S11 until all quantum operations in the quantum circuit to be compiled are extracted, completing the segmentation of the quantum circuit to be compiled, and obtaining a plurality of sub-circuits. Namely, the mapping relation is updated, and the step returns to execute S11 until all the quantum operations in the quantum line to be compiled are extracted, namely, after all the quantum operations in the quantum line to be compiled are extracted, a plurality of sub-lines are obtained, and the quantum line to be compiled is segmented. The specific pseudo code is as follows:

inputting: quantum wire

Maximum number of qubits in sub-line

. Presetting maximum value of quantum bit number as

；

And (3) outputting: quantum wire sequence

。

1. There is a sequence of quantum operations that constitute,

the number of qubits in (a) is,

；

2.

indicating an empty line;

3. if it is used

Then step 16 is entered, otherwise

Taking out the first operation;

4.

a set of quantum bits of interest;

5.

to middle

Quantum circuit is absent

Then add it into

；

6. If it is used

Entering step 8;

7. to

Quantum wire incorporation in

Entering step 3;

8. if it is not

Number of qubits contained in all lines

And wherein the number of CNOT operations that were cut

If yes, entering step 9, otherwise entering step 11;

9.

merging all lines in the system;

10.

to middle

Quantum circuit replacement

Entering step 3;

11. if it is not

Is a CNOT operation, and

if the CNOT operation in all the lines is not cut, the step 12 is executed, otherwise, the step 13 is executed;

12. the CNOT operation is cut under tensor, and COPY and XOR tensors obtained by cutting are respectively added into the CNOT operation

Step 3 is entered;

13. will be provided with

All lines in (1) are added

；

14.

Involving quantum operations only

A quantum wire of (a);

15.

to middle

Quantum circuit replacement

Entering step 3;

16.

if it is determined that

Is out of position

In (1), then add it into

；

17. Return to

；

In the pseudo code, step 1 and step 2 correspond to S10, step 3 corresponds to S11, step 4 and step 5 correspond to S12, step 6 to step 12 correspond to S13, and step 13 to step 17 correspond to S14 and S15.

Wherein the quantum wire to be compiled

As quantum wires

The pseudo code is executed to divide the quantum circuit to be compiled into a plurality of sub-circuits.

Based on the tensor network theory, compiling each sub-line into a new sub-line only including basic quantum operation respectively, including:

S20-S22 are executed on each sub-line until each sub-line is compiled into a new sub-line only containing basic quantum operation;

s20, initializing any sub-line, and opening the initialized sub-line to obtain a state;

and S21, judging whether the sub-line contained in the state obtained in the S20 meets the output condition, if so, outputting the sub-line corresponding to the state as a new sub-line corresponding to the sub-line, otherwise, executing S22, wherein in the technical field of quantum compilation, the new sub-line after compilation only comprises basic quantum operations.

S22, performing an expansion operation on the state obtained in S20 to obtain a plurality of new states, selecting one state from all the new states, taking the selected state as the state obtained in S20, and repeating S21.

The specific pseudo codes corresponding to S20-S22 are as follows:

inputting: target quantum lines to be compiled

Target accuracy

。

And (3) outputting: one comprising only fundamental quantum operations and

tensor quantum wire

And the parameter values thereof

So that

Is composed of

The decomposition is approximated.

1.

The number of qubits in (a) is,

in which there are cut qubits present in the qubit,

the tensor obtained by the middle cutting;

2.

a null sub-line;

3. to the direction of

In (1) adding

A U3 quantum operation respectively acting on the qubits

The above step (1);

4. to

In the qubit

Tensor of (3)

Adding a further effect on the qubit

U3 quantum operations on;

5.

；

6. if it is used

Then return to

And the parameter values thereof

；

7.

Entering step 6;

wherein, the steps 1 to 5 correspond to S20, the step 6 corresponds to S21, the step 7 corresponds to S22, and each sub-line is taken as a target quantum sub-line to be compiled

And executing the pseudo code, and compiling each sub-line into a new sub-line only containing basic quantum operations.

Compiling each sub-line into pseudo code of a new sub-line containing only basic quantum operations, wherein the pseudo code of the state Open (Open) is as follows:

inputting: a quantum wire

Father state

Tensor of object

。

And (3) outputting: one state in the search space

。

1.

；

2.

；

3.

；

Return to

。

The pseudo code for the expansion of state (Expand) is:

inputting: a state of waiting to be unfolded

Tensor of object

Number of qubits

。

And (3) outputting: newly opened state set

。

1.

；

2.

；

3. If it is used

Then return to

；

4.

If, if

Entering step 2;

5.

in the direction of

End-of-line effects on qubits

On CNOT operation, then to

End-of-line effects on qubits

Two U3 operations above;

6.

；

7.

in the direction of

The introduction of the start of the quantum bit

CNOT operations on, and then to

The introduction of the start of the quantum bit

Two U3 operations above;

8.

；

9.

proceed to step 4.

The search space is:

for a quantum wire under a tensor expression, the approximate compiling process can be regarded as a search process of a search space, and one state of the search space

The stored information includes: an intermediate quantum wire

（

Parameter sets for sub-operations with parameters) and specific values of their parameters

Evaluation value of the state

Parent status of this status

. Status of state

Can also be written as

. In addition, multiple states may be combined

Make upSet of (A) is denoted as

。

Technical terms of the present invention are explained as follows:

1) Quantum bit:

qubits are the fundamental unit of quantum computer storage of data. Quantum operations implement specific functions by corresponding control of qubits. In this patent, symbols are used

Representing the collection of all qubits in a quantum computer,

representing the second in quantum computers

The number of sub-bits is such that,

representing the number of quantum bits in a quantum computer.

2) Unitary matrix representation of quantum manipulation:

quantum manipulation (by symbols)

Representation) represents a specific operation that a quantum computer can perform, which contains two pieces of information: qubits of effect and specific functions. Unitary matrix (in symbols)

Representation) is one of the most common expressions of quantum manipulation. In general, one acts on

Quantum operation on qubits

Can be expressed as a size of

Of a two-dimensional matrix

And satisfy

In which

Representing a unit array.

A control not gate (CNOT gate) is a common two-qubit operation whose unitary matrix is represented as:

；

in addition, an arbitrary single qubit quantum operation can be performed with U3 with parameters (note the notation of U with unitary matrix here

Irrelevant) quantum operations. A unitary matrix of U3 quantum operations is represented as:

wherein

Three undetermined parameters which can be arbitrarily valued are adopted, and one U3 quantum operation can be converted into any single-quantum bit quantum operation through specific values.

3) Quantum operations and their tensor representations:

by default, the specific function of quantum manipulation may be represented by a unitary matrix. The scheme innovatively expresses the specific function of one quantum operation by tensor. Tensor (with sign)

Representation) is a high-dimensional matrix for a role in

Quantum operation on qubits

In other words, its tensor (denoted as

) The representation can be seen as one dimension (also called degree in tensor) as

The degree of freedom in each dimension of the high-dimensional matrix of (2), therefore,

the size of the high-dimensional matrix corresponding to the tensor of the quantum operation of the qubit is

. In addition, tensor

Degree of (can also be recorded as

. The unitary matrix representation and the tensor representation of a quantum operation can be transformed into each other, and the transformation process is the prior art.

In general, one is in

Quantum operation on qubits

Graph under tensor, as shown in FIG. 2, where the left side represents the inputIn, the right side represents the output, and the straight line (also called index) of each row corresponds to the qubit it is acting on. It should be noted that the total number of indices possessed by a tensor should equal its degree.

A graph of CNOT (controlled not gate) quantum operation under tensor is shown in fig. 3.

Suppose we first pair qubits

Performing quantum operations

For the qubit

A CNOT quantum operation is performed, a graph of these two quantum operations under tensor, as shown in fig. 4.

4) Cutting and merging of CNOT quantum operations in tensor representation:

for CNOT quantum manipulation we can perform a special manipulation, called slicing, on it under the tensor. The cut may change the tensor corresponding to one CNOT quantum operation (degree 4) to two tensors of degree 3 (COPY tensor and XOR tensor, respectively). It should be noted that the degree of cutting increases from 4 to 6, and two new indicators are generated. One acting on qubits

Graph of CNOT quantum operations on after cutting, as shown in fig. 5.

The upper half part is a COPY tensor, the lower half part is an XOR tensor, two straight lines cut off in the middle are two newly-added indexes, and the two indexes do not correspond to any quantum bit.

The combination of COPY and XOR is the inverse operation of CNOT quantum operation cutting under tensor, which can restore the COPY and XOR tensors obtained by cutting to the original CNOT quantum operation.

5) Contraction between tensors

Contraction is a fundamental operation in tensor theory that can combine two tensors into a new tensor. In quantum programming, assume we want to pair tensors

A shrink operation is performed, which process can be described as

In which

To shrink the resulting new tensor (the specific calculation of which is prior art),

for quantum operations corresponding to said tensors, the quantum bit acted on by the quantum operation is

The union of the qubit sets is acted upon as shown in fig. 6.

For example, we want to shrink the tensors in the two quantum processes, the output of the process can be written as

Wherein

And carrying out quantum operation corresponding to the newly obtained tensor.

The graph of (a) is shown in fig. 7.

The quantum bit set for the two quantum operation functions is

Therefore, it is

Degree of 4, respectively corresponding to the qubits

As shown in fig. 8.

For another example, we want to shrink the tensors in the two quantum processes, the output of the process can be recorded as

Wherein

And carrying out quantum operation corresponding to the newly obtained tensor.

The graph of (a) is shown in fig. 9.

The qubits for which the two quantum operations described above work are grouped together

Therefore, it is

Degree of 6, corresponding to qubits respectively

As shown in fig. 10.

And carrying out quantum operation corresponding to the newly obtained tensor.

The graph of (a) is shown in fig. 11.

The quantum bit set for the two quantum operation functions is

In addition, the COPY tensor has an index which is irrelevant to the qubit, so

Degree of 5, corresponding to qubits respectively

And

and a qubit-independent index of the original COPY tensor.

6) Fundamental quantum operations:

in the quantum programming process, it will be assumed that any quantum operation can be performed on a quantum computer. In practical cases, however, a quantum computer can only perform some specific quantum operations, and these operations that can be performed by a specific quantum computer are referred to as basic quantum operations of the quantum computer. The basic quantum operations are assumed in this patent to be single-qubit U3 operations and two-qubit CNOT operations. It should be noted that for most practical quantum computers, the U3 operation and CNOT operation can be easily compiled into their corresponding basic quantum operations. The quantum wires and their tensors are represented as shown in fig. 12.

Quantum wires (using symbols)

Representation) is a common description of quantum processes, which generally consist of a quantum bit and a series of quantum operations, if each quantum operation is represented by a tensor, a tensor representation of the quantum line can be obtained. The upper diagram shows a tensor representation of a quantum wire, which contains two qubits

Each line represents a corresponding qubit and also contains three quantum operations, respectively

And CNOT.

7) Classical modeling of quantum wires under tensor representation:

by performing the contraction operation on the tensors in the quantum wire in a certain order (for example, from left to right), only one tensor can be left in the quantum wire, and the process is called a classical simulation of the quantum wire and is marked as

Wherein

A tensor representation corresponding to the resulting quantum operation.

For example, for the quantum wires shown in the previous figures, in a classical simulation process, the tensors are first aligned

And

is contracted and is marked as

At this time, only tensor exists in the line

As shown in fig. 13.

Then, it is executed again

When only one tensor exists in the line

As shown in fig. 14.

I.e. the output of the classical simulation.

8) Distance between the two tensors:

distance (

) For inscribing two tensors acting on the same qubit (not to be noted as

) The degree of similarity between them. It can be expressed as:

wherein

For averaging errors, the operation is performed on two tensors with the same degree, the output of the operation is a real number greater than or equal to 0, which can characterize the similarity degree of the two tensors (the lower the value is, the more similar the value is, the 0 is taken to represent complete equivalence), and the specific calculation process of the operation is the prior art.

9) Approximate compilation of quantum wires:

for a quantum wire

And a sufficiently small positive number

When another quantum wire is present

And satisfy

At first, call

As quantum wires

Is/are as follows

And (4) approximate compiling. The performance of a near quantum compiler can be measured by the number of CNOT quantum operations in its output quantum wires, which is the smaller the number of CNOT quantum operations in the output quantum wires, the better the performance of the near quantum compiler.

10 Approximate compilation of quantum wires without XOR and COPY tensors:

for quantum wires under a tensor representation

If the vector does not contain XOR and COPY tensors (the CNOT tensor is not cut), the existing approximate quantum compiler can be called to carry out approximate compilation, and the process is marked as

Wherein

In order to be the output line,

to a target accuracy

11 ) quantum line optimizer

Some quantum operations in a quantum circuit may have one or more parameters to be determined, such as the aforementioned single-qubit U3 operation, and specific values of these parameters need to be determined during the compilation process, which may be regarded as an optimization problem, and the specific tools for solving this problem are referred to in this patent as quantum operation optimizers (prior art). Specifically, the input to a quantum manipulation optimizer is a quantum wire containing a quantum manipulation of a pending parameter

And the target sheetQuantity of

Output is as

Specific value set of middle parameters

And need to make

Is as small as possible. The calling process of the quantum operation optimizer is noted in the present invention as

。

The scheme is divided into three parts of line cutting, sub-line compiling and line combining. The circuit cutting module divides a general quantum circuit with a large number of sub-bits (input circuit of the compiler) into a plurality of sub-circuits with a small number of sub-bits; sub-line compilation is based on a tensor network theory, the sub-lines are compiled into new quantum lines only containing basic quantum operations, and the sub-lines before and after compilation are approximately equivalent; the line combination combines the sub-lines with the new small number of sub-bits obtained by compiling to obtain a line with a new large number of sub-bits as the output result of the compiler, so that the output line and the input line are approximately equivalent, and the high-performance compiling of the quantum line with any number of quantum bits can be realized.

In the above embodiments, although the steps are numbered as S1, S2, etc., but only the specific embodiments are given in the present application, and a person skilled in the art may adjust the execution sequence of S1, S2, etc. according to the actual situation, which is also within the protection scope of the present invention, it is understood that some embodiments may include some or all of the above embodiments.

As shown in fig. 2, an approximate quantum compiling system 200 based on tensor network according to an embodiment of the present invention includes a segmentation module 210, a compiling module 220, and a combination determining module 230;

the segmentation module 210 is configured to: dividing the quantum circuit to be compiled into a plurality of sub-circuits, wherein the quantum bit of each sub-circuit is not more than the maximum value of the number of preset quantum bits;

the compiling module 220 is configured to: on the basis of a tensor network theory, compiling each sub-line into a new sub-line only comprising basic quantum operation respectively, and enabling any sub-line to be approximately equivalent to the new sub-line corresponding to the sub-line;

the combination determination module 230 is configured to: and combining all the new sub-circuits to obtain a new quantum circuit, and determining the new quantum circuit as a final compiling result.

Optionally, in the foregoing technical solution, the segmentation module 210 includes an initial construction module, a sequence extraction module, a determination module, an update module, a first judgment module, and an update repeat call module;

the initial building block is configured to: initializing a plurality of sub-circuits to be constructed, and constructing a mapping relation from the quantum bits in the quantum circuits to be compiled to the sub-circuits to be constructed, wherein each quantum bit in the quantum circuits to be compiled corresponds to one sub-circuit to be constructed;

the sequence extraction module is to: sequentially extracting the quantum operations in the quantum circuit to be compiled according to the execution sequence of the quantum operations in the quantum circuit to be compiled;

the determination module is to: determining the sub-lines to be constructed corresponding to the quantum operations extracted by the sequence extraction module from all the sub-lines to be constructed according to the mapping relation;

the update module is to: updating the sub-circuit to be constructed corresponding to the quantum operation extracted by the sequential extraction module according to the quantum operation of the sub-circuit to be constructed corresponding to the quantum operation extracted by the sequential extraction module and the preset maximum value of the number of quantum bits;

the first judging module is used for: judging whether any sub-line to be constructed is constructed or not, if so, determining the sub-line to be constructed as the sub-line, and generating a new sub-line to be constructed;

the update repeat call module is to: and updating the mapping relation, and recalling the sequence extraction module, the determination module and the updating module until all quantum operations in the quantum circuit to be compiled are extracted, completing the segmentation of the quantum circuit to be compiled, and obtaining a plurality of sub-circuits.

Optionally, in the foregoing technical solution, the compiling module 220 includes a repeat call module, an initialization opening module, a second judging module, and an expansion repeat call module;

the repeat call module is to: calling an initialization opening module, a second judgment module and a development repeated calling module for each sub-line until each sub-line is compiled into a new sub-line only containing basic quantum operation;

the initialization opening module is used for: initializing any sub-line, and opening the initialized sub-line to obtain a state;

the second judging module is used for: judging whether sub-circuits contained in the state obtained by initializing the opening module meet output conditions or not, if so, outputting the sub-circuit corresponding to the state as a new sub-circuit corresponding to the sub-circuit, and if not, calling a development repeat calling module;

the unwind repeat call module is to: and performing expansion operation on the state obtained by initializing the opening module to obtain a plurality of new states, selecting one state from all the new states, taking the selected state as the state obtained by initializing the opening module, and repeatedly calling the second judgment module.

The above steps for realizing the corresponding functions of each parameter and each unit module in the approximate quantum compiling system based on the tensor network can refer to each parameter and step in the embodiment of the approximate quantum compiling method based on the tensor network, and are not described herein again.

The storage medium of the embodiment of the present invention stores instructions, and when the instructions are read by a computer, the computer is caused to execute any one of the above approximate quantum compiling methods based on the tensor network.

The electronic device of the embodiment of the invention comprises a processor and the storage medium, wherein the processor executes instructions in the storage medium, and the electronic device can be a computer, a mobile phone and the like.

As will be appreciated by one skilled in the art, the present invention may be embodied as a system, method or computer program product.

Accordingly, the present disclosure may be embodied in the form of: the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit," module "or" system. Furthermore, in some embodiments, the invention may also be embodied in the form of a computer program product in one or more computer-readable media having computer-readable program code embodied in the medium.

Any combination of one or more computer-readable media may be employed. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. An approximate quantum compiling method based on a tensor network, comprising:

s2, compiling each sub-line into a new sub-line only comprising basic quantum operation based on a tensor network theory, and enabling any sub-line to be approximately equivalent to the new sub-line corresponding to the sub-line;

2. The approximate quantum compiling method based on the tensor network as recited in claim 1, wherein the dividing the quantum wire to be compiled into a plurality of sub-wires comprises:

s10, initializing a plurality of sub-lines to be constructed, and constructing a mapping relation from the quantum bits in the quantum lines to be compiled to the sub-lines to be constructed, wherein each quantum bit in the quantum lines to be compiled corresponds to one sub-line to be constructed;

s13, updating the sub-circuit to be constructed corresponding to the quantum operation extracted in the S11 according to the quantum operation of the sub-circuit to be constructed corresponding to the quantum operation extracted in the S11 and the preset maximum value of the number of quantum bits;

s14, judging whether any sub-line to be constructed is constructed or not, if so, determining the sub-line to be constructed as the sub-line, and generating a new sub-line to be constructed;

and S15, updating the mapping relation, returning to execute the S11 until all quantum operations in the quantum line to be compiled are extracted, and completing the segmentation of the quantum line to be compiled to obtain a plurality of sub-lines.

3. The approximate quantum compiling method based on the tensor network as recited in claim 2, wherein the tensor network theory-based compiling each sub-line into a new sub-line containing only fundamental quantum operations respectively comprises:

respectively executing S20-S22 on each sub-line until each sub-line is compiled into a new sub-line only containing basic quantum operation;

s21, judging whether sub-lines contained in the state obtained in the S20 meet output conditions or not, if so, outputting the sub-line corresponding to the state as a new sub-line corresponding to the sub-line, and if not, executing S22;

4. An approximate quantum compiling system based on a tensor network is characterized by comprising a segmentation module, a compiling module and a combination determining module;

the compiling module is configured to: on the basis of a tensor network theory, compiling each sub-line into a new sub-line only containing basic quantum operation, and enabling any sub-line to be approximately equivalent to the new sub-line corresponding to the sub-line;

the combination determination module is to: and combining all the new sub-lines to obtain a new quantum line, and determining the new quantum line as a final compiling result.

5. The tensor network-based approximate quantum compiling system of claim 4, wherein the segmenting module comprises an initial constructing module, a sequential extracting module, a determining module, an updating module, a first judging module and an updating repeat calling module;

the initial building module is to: initializing a plurality of sub-lines to be constructed, and constructing a mapping relation from the quantum bits in the quantum lines to be compiled to the sub-lines to be constructed, wherein each quantum bit in the quantum lines to be compiled corresponds to one sub-line to be constructed;

the sequential extraction module is to: sequentially extracting the quantum operations in the quantum circuit to be compiled according to the execution sequence of the quantum operations in the quantum circuit to be compiled;

the determination module is to: determining sub-lines to be constructed corresponding to the quantum operations extracted by the sequence extraction module from all the sub-lines to be constructed according to the mapping relation;

the update module is to: updating the sub-circuit to be constructed corresponding to the quantum operation extracted by the sequential extraction module according to the quantum operation of the sub-circuit to be constructed corresponding to the quantum operation extracted by the sequential extraction module and a preset maximum value of the number of quantum bits;

the update repeat call module is configured to: and updating the mapping relation, and recalling the sequence extraction module, the determination module and the updating module until all quantum operations in the quantum line to be compiled are extracted, completing the segmentation of the quantum line to be compiled, and obtaining a plurality of sub-lines.

6. The tensor network-based approximate quantum compiling system of claim 5, wherein the compiling module comprises a repeat calling module, an initialization opening module, a second judging module and an unfolding repeat calling module;

the repeat call module is configured to: calling the initialization opening module, the second judgment module and the expansion repeated calling module for each sub-line until each sub-line is compiled into a new sub-line only comprising basic quantum operation;

the second judging module is used for: judging whether sub-circuits contained in the state obtained by initializing the opening module meet output conditions or not, if so, outputting the sub-circuit corresponding to the state as a new sub-circuit corresponding to the sub-circuit, and if not, calling the expansion repeated calling module;

the expansion repeat call module is used for: and performing expansion operation on the state obtained by initializing the opening module to obtain a plurality of new states, selecting one state from all the new states, taking the selected state as the state obtained by initializing the opening module, and repeatedly calling the second judgment module.

7. A storage medium having stored therein instructions which, when read by a computer, cause the computer to execute a tensor network-based approximate quantum compilation method as recited in any one of claims 1 to 3.

8. An electronic device comprising the storage medium of claim 7 and a processor, wherein the processor executes instructions in the storage medium.