Creating quantum circuit diagrams in TikZ
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README.rst

⟨q|pic⟩: Quantum circuits made easy

docs/images/qpic.png

A compiler from quantum circuits to graphical representations.

Features

The ⟨q|pic⟩ language provides a concise, readable, ASCII format for describing quantum circuits. qpic converts ⟨q|pic⟩ files to the scientific paper standard of LaTeX using TikZ graphic commands.

  • Automatic placement of circuit components.
  • Human readable.
  • Input ⟨q|pic⟩ syntax can be produced by other scripts.
  • Can be included in LaTeX documents in TikZ or PDF form.

⟨q|pic⟩ produces high quality graphics quickly. The following graphic illustrating part of a ripple carry adder

docs/images/Adder_CDKM_MAJ.png

is compiled from the ⟨q|pic⟩ code

a W a a\oplus{c}
b W b b\oplus{c}
c W c \mbox{MAJ}(a,b,c)

a b c G \rotatebox{90}{MAJ}
=
+b c
+a c
a b +c

Examples

Basic quantum teleportation circuit

docs/images/BasicTeleportation.png

This classic diagram derives from the following code:

a W |\psi\rangle
b c W |\beta_{00}\rangle<
c W |\psi\rangle
a +b
a H
a b M
c X b:owire
c Z a:owire

Decorated quantum teleportation circuit

⟨q|pic⟩ has additional features for commenting or highlighting parts of a circuit.

docs/images/QuantumTeleportation.png

This diagram derives from the following:

PREAMBLE \providecommand{\K}[1]{\left|#1\right\rangle} # Define ket command
a  W \K{\phi} [x]
x1 W type=o # Empty wire used for positioning
x0 W style=dashed # Dividing line
x2 W type=o # Empty wire used for positioning
b0 W \K{0} [y]
b1 W \K{0} \K{\phi}

VERTICAL 0
b1 H    % $\K{\phi}\K{0}(\K{0}{+}\K{1})$
+b0 b1  % $(\alpha\K{0}{+}\beta\K{1})(\K{00}{+}\K{11})$
b0 x1 PERMUTE
+b0 a   %$\scriptstyle\alpha\K{0}(\K{00}{+}\K{11}){+}\beta\K{1}(\K{10}{+}\K{01})$
a H     % $\sum_{x,y}\K{xy}(\alpha\K{y}{+}(-1)^x\beta\K{\bar{y}})$
a b0 M  % $[xy](\alpha\K{y}{+}(-1)^x\beta\K{\bar{y}})$
x1 x2 a b0 PERMUTE
+b1 b0  % $[xy](\alpha\K{0}{+}(-1)^x\beta\K{1})$
b1 a    % $[xy](\alpha\K{0}{+}\beta\K{1})$

# Colored boxes
b0 b1 x1 x2 @ 0 2 fill=green style=rounded_corners %% $[qq]$ Quantum entanglement
a b0 x2 x1 @ 6 6 fill=blue style=rounded_corners %% \hspace{.5cm}$2[c\rightarrow c]$ Classical channel

For an explanation of qpic commands and more examples, see the official documentation.

Installation

Recommended installation method is pip. Current versions of Python 2 and 3 include pip. For older versions, use pip installation instructions.

pip install qpic

If you do not have permission to install or wish to install qpic as a single user, add $HOME/.local/bin to your $PATH and install using

pip install --user qpic

Uninstall

To uninstall qpic simply type

pip uninstall qpic

Stand alone script

To try out the basic script without installation:

  1. Download the file qpic.py. (located in the qpic directory)
  2. Run python qpic.py your_file.qpic > your_file.tex.

Running ⟨q|pic⟩

qpic generates TikZ code by default. qpic can also generate pdf files using pdflatex and png files using convert (from ImageMagic).

Create TikZ file diagram.tikz

qpic -f tikz diagram.qpic

Create PDF file diagram.pdf

qpic -f pdf diagram.qpic

Create PNG file diagram.png

qpic -f png diagram.qpic

Using ⟨q|pic⟩ with LaTeX

Including graphics in LaTeX documents

There are two main methods for including ⟨q|pic⟩ in LaTeX documents. Each has its advantage in certain areas. They are:

  • Include TikZ code directly
  • Include as a PDF graphic

TikZ

qpic my_graphic.qpic produces a TikZ file named my_graphic.tikz, which can be directly included into a normal LaTeX document. You will need to add

\usepackage{tikz}

to the preamble of your paper. Graphics can then be included with the command:

\input{filename.tikz}

In some cases, additional TeX commands may be required in the preamble. (These will be in the .tikz file preceded by %!.) See the full ⟨q|pic⟩ documentation for when additional packages are required.

PDF

qpic -f pdf my_graphic.qpic will produce a PDF file named my_graphic.pdf. This graphic can be viewed directly with a PDF viewer. To insert the graphic into a LaTeX document, add the following line to the preamble:

\usepackage{graphicx}

and include the file using the command:

\includegraphics{my_graphic.pdf}

This method requires the document to be processed with pdfLaTeX. For further information see the full ⟨q|pic⟩ documentation.