Technical background

On the one hand, this paper starts with the printing of quantum circuits , Introduced a simple python Quantum circuit engineering . And based on this simple little project , By the way, we introduced python Of API Automatic document generation tool Sphinx The basic use method .

Background knowledge of quantum circuits

In previous blogs , There was an introduction to Using the open source quantum computing programming framework ProjectQ Drawing quantum circuits , It will output us a tex Format of the circuit diagram , It can be used directly in the article . About quantum circuits and quantum logic gate operations , In this article Blog There is a relatively preliminary introduction to . And the project created in this article , Is directly in cmd Print out the quantum circuit in the form of string in the window , alike , In quantum computing resource estimation and Quantum Circuit Engineering , Can have a certain effect .

Automated document generation solutions

For a more elegant python For open source projects , A brief document is essential . Generally one python The project documentation consists of two parts ： Part of it is with markdown Written instruction document , Its purpose is to outline the key content of the whole project , And maybe a few examples of usage . This part of the document can be used first markdown Write , And then through some open source tools , Such as mkdocs And so on read_the_docs The format of the document .read_the_docs The format of the document is shown in the figure below , You can also refer to it directly Official documents . The second part of the document is specific to each function 、 Interface documentation for each class . In the development stage , Let's first write the annotation document according to the format requirements , And then through open source tools Sphinx It can be generated automatically API Interface document .

install sphinx

Here we use it directly python Package management tools pip To install Sphinx And one. read_the_docs Format python library . If you don't need to use read_the_docs Format can also be installed without the latter , It's just that the latter is python It's also the most commonly used document format in open source projects , And can cooperate with read_the_docs Website API Document hosting , Therefore, it is recommended to use .

[dechin@dechin-manjaro circuit]$ python3 -m pip install sphinx

Requirement already satisfied: sphinx in /home/dechin/anaconda3/lib/python3.8/site-packages (3.4.3)

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[dechin@dechin-manjaro circuit]$ python3 -m pip install sphinx-rtd-theme

Collecting sphinx-rtd-theme

Downloading sphinx_rtd_theme-0.5.1-py2.py3-none-any.whl (2.8 MB)

|████████████████████████████████| 2.8 MB 74 kB/s

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Installing collected packages: sphinx-rtd-theme

Successfully installed sphinx-rtd-theme-0.5.1

be based on python Quantum circuits print small projects

Let's take a look at the method and effect , Let's go back to the principle of code implementation ：

if __name__ == '__main__':

qc = QuantumCircuit(3)

qc.apply(0, 0)

qc.apply(1, (1,0))

qc.apply(1, (2,1))

qc.apply(1, (2,0))

qc.apply(2)

print (qc)

The output is as follows ( Pay attention to the font with equal width )：

 |0> |0> |0>

| | |

| | h

| | |

| x ----- c

| | |

x ----- c |

| | |

x ----- | ----- c

| | |

m m m

Here we can learn , The core function of this project is to construct a quantum circuit object , And the quantum gate operation is applied to this object one by one , You can output the corresponding quantum circuit string . Next, let's look at the source code implementation ：

# qcprinter.py

"""

The module used for print a quantum circuit in string format.

"""
class QuantumCircuit:

"""The class of quantum circuit from input quantum logical gates.
Parameters

----------

qubits : int

Totcal number of qubits used in this quantum circuit.
Returns

-------

str

The string format of quantum circuit.
How to use?

-------
>>> qc = QuantumCircuit(3)

>>> qc.apply(0, 0)

>>> qc.apply(1, (1,0))

>>> qc.apply(1, (2,1))

>>> qc.apply(1, (2,0))

>>> qc.apply(2)

>>> print (qc)

Example output

-------
>>> |0> |0> |0>

>>> | | |

>>> | | h

>>> | | |

>>> | x ----- c

>>> | | |

>>> x ----- c |

>>> | | |

>>> x ----- | ----- c

>>> | | |

>>> m m m

"""

def __init__(self, qubits=0):

self.qubits = qubits

self.str_circuit = ' |0>\t' * self.qubits + ' \n'
def __str__(self):

return self.str_circuit
def apply(self, gate_type, qubit_index=0):

"""The function used to apply quantum logical gates on quantum state.
Parameters

----------

gate_type : int

An index number represents for different type of quantum logical gates. 0 for h gate,

1 for cx gate and 2 for measure gate.

qubit_index: int, tuple, none

The qubit index quantum logical gates allpied on. If the gate_type is h, the qubit_index

would be int format. If the gate_type is cx, the qubit_index should be a tuple. If the

gate_type is m, that means do measurement to all qubits, thus you do not need to set

the value of qubit_index.
Returns

-------

str

The string format of quantum circuit.

"""

if gate_type == 0:

self.str_circuit += ' | \t' * self.qubits + '\n'

self.str_circuit += ' | \t' * (self.qubits - qubit_index - 1) + ' h \t' + ' | \t' * (qubit_index) + '\n'

elif gate_type == 1:

self.str_circuit += ' | \t' * self.qubits + '\n'

self.str_circuit += ' | \t' * (self.qubits - qubit_index[0] - 1) + ' x'

for i in range(qubit_index[0] - qubit_index[1] - 1):

self.str_circuit += ' ' + '-' * 5 + ' |'

self.str_circuit += ' ' + '-' * 5 + ' c \t'

self.str_circuit += ' | \t' * (qubit_index[1]) + '\n'

elif gate_type == 2:

self.str_circuit += ' | \t' * self.qubits + '\n'

self.str_circuit += ' m \t' * self.qubits + '\n'

else:

pass

In this simple code implementation , We mainly set up a magic function for the class of quantum circuit __str__, Take the string of quantum circuit we need as the string return value of the whole object ( About python The use of magic function can refer to the previous article Blog Introduce ). The core function of this string class is realized through string splicing , We're just going to go on and on . Here for convenience , We use integer numbers instead of quantum logic gate operations ：0 representative \(H\) door ,1 representative \(CNOT\) door ,2 Represents the global quantum measurement operation . meanwhile , For display API The process of making documents , Here we have written part of the sample comment code in the class and function , In the next chapter, I'll introduce the effect of the document .

sphinx Document generation and effect list

use first sphinx-quickstart To generate some configuration files ：

[dechin@dechin-manjaro circuit]$ sphinx-quickstart

Welcome to use Sphinx 3.5.1 Quick configuration tools .
Please enter values for the following settings (just press Enter to

accept a default value, if one is given in brackets).
Selected root path: .
You have two options for placing the build directory for Sphinx output.

Either, you use a directory "_build" within the root path, or you separate

"source" and "build" directories within the root path.

> Independent source files and build directories （y/n） [n]: y
The project name will occur in several places in the built documentation.

> Project name : qcprinter

> Author's name : DechinPhy

> Project release []: 1.0
If the documents are to be written in a language other than English,

you can select a language here by its language code. Sphinx will then

translate text that it generates into that language.
For a list of supported codes, see

https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-language.

> Project language [en]: en
create a file /home/dechin/projects/2021-quantum/circuit/source/conf.py.

create a file /home/dechin/projects/2021-quantum/circuit/source/index.rst.

create a file /home/dechin/projects/2021-quantum/circuit/Makefile.

create a file /home/dechin/projects/2021-quantum/circuit/make.bat.
complete ： Created initial directory structure .
You should now populate your master file /home/dechin/projects/2021-quantum/circuit/source/index.rst and create other documentation

source files. Use the Makefile to build the docs, like so:

make builder

where "builder" is one of the supported builders, e.g. html, latex or linkcheck.

After this series of configurations , Several new files will be generated in the current directory ( Because we chose build and source The pattern of separation , So there will be 2 A catalog )：

[dechin@dechin-manjaro circuit]$ ll

Total usage 52

drwxr-xr-x 2 dechin dechin 4096 2 month 23 00:04 build

-rw-r--r-- 1 dechin dechin 799 2 month 23 00:04 make.bat

-rw-r--r-- 1 dechin dechin 638 2 month 23 00:04 Makefile

-rw-r--r-- 1 dechin dechin 3055 2 month 22 23:26 qcprinter.py

drwxr-xr-x 4 dechin dechin 4096 2 month 23 00:04 source

stay source Some configuration files will be generated in the directory , Here we need to modify one of the conf.py file ：

[dechin@dechin-manjaro circuit]$ cd source/

[dechin@dechin-manjaro source]$ ll

Total usage 16

-rw-r--r-- 1 dechin dechin 1884 2 month 23 00:04 conf.py

-rw-r--r-- 1 dechin dechin 443 2 month 23 00:04 index.rst

drwxr-xr-x 2 dechin dechin 4096 2 month 23 00:04 _static

drwxr-xr-x 2 dechin dechin 4096 2 month 23 00:04 _templates

You can refer to the configuration plan of the building owner , Here we mainly configure the theme to rtd The format of , At the same time opened autodoc And through sys Configured index directory ( If the index directory is not configured , It is possible that the module cannot be found , So it can't be generated normally API Interface document )：

[dechin@dechin-20n2s01200 circuit]$ cat source/conf.py

# Configuration file for the Sphinx documentation builder.

#

# This file only contains a selection of the most common options. For a full

# list see the documentation:

# https://www.sphinx-doc.org/en/master/usage/configuration.html
# -- Path setup --------------------------------------------------------------
# If extensions (or modules to document with autodoc) are in another directory,

# add these directories to sys.path here. If the directory is relative to the

# documentation root, use os.path.abspath to make it absolute, like shown here.

#

import os

import sys

sys.path.insert(0, os.path.abspath('..'))
# -- Project information -----------------------------------------------------
project = 'qcprinter'

copyright = '2021, DechinPhy'

author = 'DechinPhy'
# The full version, including alpha/beta/rc tags

release = '1.0'
# -- General configuration ---------------------------------------------------

import sphinx_rtd_theme

# Add any Sphinx extension module names here, as strings. They can be

# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom

# ones.

extensions = ["sphinx_rtd_theme", "sphinx.ext.autodoc", "sphinx.ext.autosummary"

]
# Add any paths that contain templates here, relative to this directory.

templates_path = ['_templates']
# List of patterns, relative to source directory, that match files and

# directories to ignore when looking for source files.

# This pattern also affects html_static_path and html_extra_path.

exclude_patterns = []
# -- Options for HTML output -------------------------------------------------
# The theme to use for HTML and HTML Help pages. See the documentation for

# a list of builtin themes.

#

html_theme = 'sphinx_rtd_theme'
# Add any paths that contain custom static files (such as style sheets) here,

# relative to this directory. They are copied after the builtin static files,

# so a file named "default.css" will overwrite the builtin "default.css".

html_static_path = ['_static']

perform sphinx-build Instructions will be source Medium rst The document is compiled into html file , And output to the build Under the table of contents ：

[dechin@dechin-manjaro circuit]$ sphinx-build source/ build/

Running Sphinx v3.5.1

load pickled Environmental Science ... complete 

structure [mo]： 0 individual po The target file for the file has expired 

structure [html]： 0 Target files for source files are out of date 

Update the environment : Have been added 0,1 Has been changed ,0 Removed 

Reading source ... [100%] qcprinter

/home/dechin/projects/2021-quantum/circuit/qcprinter.py:docstring of qcprinter.QuantumCircuit:4: WARNING: Unexpected section title or transition.
----------

/home/dechin/projects/2021-quantum/circuit/qcprinter.py:docstring of qcprinter.QuantumCircuit:9: WARNING: Unexpected section title or transition.
-------

/home/dechin/projects/2021-quantum/circuit/qcprinter.py:docstring of qcprinter.QuantumCircuit:14: WARNING: Unexpected section title or transition.
-------

/home/dechin/projects/2021-quantum/circuit/qcprinter.py:docstring of qcprinter.QuantumCircuit:24: WARNING: Unexpected section title or transition.
-------

/home/dechin/projects/2021-quantum/circuit/qcprinter.py:docstring of qcprinter.QuantumCircuit.apply:4: WARNING: Unexpected section title or transition.
----------

/home/dechin/projects/2021-quantum/circuit/qcprinter.py:docstring of qcprinter.QuantumCircuit.apply:15: WARNING: Unexpected section title or transition.
-------

Find files that are currently out of date ... Can't find 

pickling Environmental Science ... complete 

Check consistency ... /home/dechin/projects/2021-quantum/circuit/source/modules.rst: WARNING: The document is not added to any tree 

complete 

Ready to file ... complete 

Write output ... [ 33%] index Write output ... [ 66%] modules Write output ... [100%] qcprinter

generating indices... genindex py-modindex complete 

writing additional pages... search complete 

copying static files... complete 

copying extra files... complete 

dumping search index in English (code: en)... complete 

dumping object inventory... complete 

build success , 7 warnings.
HTML The page is saved in build Catalog .

In the process of this execution , Some of the alerts are related to annotation specifications , In fact, it doesn't matter if you don't have to deal with it . Next you can open build Catalog , View the generated html file , First of all, we can open index.html, It's a common index of home page , The general content is shown in the figure below ：

Let's click here first index and module Look at the content , They are shown in the following two figures ：

Finally, in the index list, we click to enter qcprinter In this class , To see the detailed class documentation ：

The corresponding function annotation content will also be reflected in the interface document ：

It should be noted that , If the related class or function is a protected type , So in sphinx It will not be displayed in the generated document ( Automatically ignored during construction ).

Summary

In this article , We print it mainly through a quantum circuit python Project introduction , By the way sphinx take python Automatic generation of project annotation documents API Interface document , Completed a brief analysis of project development and document output process , Master more ways to use tools in actual combat .

Copyright notice

The first link to this article is ：https://www.cnblogs.com/dechinphy/p/qcprinter.html

author ID：DechinPhy

For more original articles, please refer to ：https://www.cnblogs.com/dechinphy/

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Using Python to write a simple project of quantum circuit printing, and using Sphinx to automatically generate API documents