Installation

qecsim is available from the Python Package Index (PyPI) for installation using the Python package installer pip. Optionally, logging and a faster matching library can be configured.

Package

qecsim requires Python 3.5+ and can be installed and upgraded using pip:

$ pip install -U qecsim

A nice way to install qecsim is using a virtual environment:

$ python3 --version             # qecsim requires Python 3.5+
Python 3.7.8
$ python3 -m venv venv          # create new virtual environment
$ source venv/bin/activate      # activate venv (Windows: venv\Scripts\activate)
(venv) $ pip install qecsim     # install qecsim
...
Successfully installed ... qecsim-1.0b9 ...
(venv) $
(venv) $ qecsim --version       # verify qecsim cli
qecsim, version 1.0b9
(venv) $ deactivate             # deactivate venv
$

Logging configuration (optional)

By default, qecsim uses the logging configuration provided by logging.basicConfig(). Optionally, logging may be configured using a file parsed with logging.config.fileConfig(). The following locations are searched in order:

  • $QECSIM_CFG/logging_qecsim.ini

  • ./logging_qecsim.ini

  • ~/.qecsim/logging_qecsim.ini

where QECSIM_CFG is an environment variable and ~ indicates the current user’s home directory. An example logging configuration file is available here: logging_qecsim.ini

Fast matching library (optional)

Several decoders included with qecsim use minimum-weight perfect matching in graphs via qecsim.graphtools.mwpm(). By default, qecsim will use a Python matching implementation provided by NetworkX. Optionally, qecsim can be configured to use Blossom V, a fast C++ matching implementation, due to Vladimir Kolmogorov:

Vladimir Kolmogorov. “Blossom V: A new implementation of a minimum cost perfect matching algorithm.” In Mathematical Programming Computation (MPC), July 2009, 1(1):43-67.

The licence for Blossom V does not permit public redistribution of the code or its derivatives (see Blossom V and the Blossom V README.TXT file for full details of the license and citation requirements). Therefore, Blossom V is not packaged with qecsim.

If your use case satisfies the license requirements of Blossom V, you can configure qecsim to use Blossom V as follows:

$ tar -xzf blossom5-v2.05.src.tar.gz
$ tar -xzf blossom5-v2.05.pyw.tar.gz
$ cp blossom5-v2.05.pyw/* blossom5-v2.05.src/
$ cd blossom5-v2.05.src/
$ make -f Makefile-pyw
...
c++ -shared ... -o libpypm.so

  • Copy libpypm.so to one of the following locations, which are searched in order by qecsim:

    • $QECSIM_CFG/clib/libpypm.so

    • ./clib/libpypm.so

    • ~/.qecsim/clib/libpypm.so

    where QECSIM_CFG is an environment variable and ~ indicates the current user’s home directory.

  • Check that Blossom V is available to qecsim:

>>> from qecsim.graphtools import blossom5
>>> blossom5.available()
True

This procedure, for installing Blossom V, has been tested on Linux and MacOS. The Blossom V README.TXT file states that it should compile with the Microsoft Visual C++ compiler, therefore the above procedure, with some adaptation, should work on Windows.