KLayout Standalone Usage

The Developer Setup or Getting started (Salt package) sections described setting up KQCircuits for use with KLayout Editor (GUI). However, KQC can also be used without KLayout Editor by using the standalone KLayout Python module. This lets you develop and use KQCircuits completely within any Python development environment of your choice, without running KLayout GUI. For example, any debugger can then be used and automated tests can be performed. The KQCircuits elements can also be visualized using any suitable viewer or library during development.


If you want to run KQCircuits outside of the KLayout Editor, you will need Python 3 and pip installed.

Successfully tested with

  • Python 3.7.6, 3.8.5, 3.10.12

Older versions of klayout (<0.28) do not support certain new features of KQCircuits. If you want to use older klayout you may need to check out a suitable older version of KQCircuits too. API changes of klayout are backwards compatible so you are safe using older KQCircuits versions with the latest KLayout.


Set up a Python virtual environment, “venv”.

If you have not yet done so, git clone the KQCircuits source code from https://github.com/iqm-finland/KQCircuits to a location of your choice.

This section explains how to install KQC in “development mode”, so that a link to your local KQC repo is added to the python environment. When using KQC installed in this way, the version in your local repo is thus used.

Standard, Not Secure Installation

To do this, activate your python environment and write in command prompt / terminal:

python -m pip install -e klayout_package/python

The previous command installs only the packages which are always required when using KQC. Other packages may be required for specific purposes, and these can be installed by using instead a command like:

python -m pip install -e "klayout_package/python[docs,tests,notebooks,simulations]"

You can choose for which purposes you want to install the requirements by modifying the text in the square brackets. Note that there should not be any spaces within the brackets.

Reproducible, Secure Installation

This is just like the standard installation but with pinned and hashed dependencies resulting in a more secure and reproducible environment. You’ll need pip-tools installed for this.

First install KQCircuits’ dependencies and any other set of requirements you may need. This needs to be done only once per venv at initial setup time or when any of the used *requirements.txt files change. In this example we only install KQCircuits’, documentation building’s and pytest’s dependencies:

cd klayout_package/python
pip-sync requirements.txt doc-requirements.txt test-requirements.txt

Note the other *requirement.txt files in this folder. Any combination of them is allowed but KQCircuits’ requirements (requirements.txt) are always needed.

Also note the OS-prefixes, win- or mac-, you are supposed to use these when running on Windows or Mac. The prefixless files are for Linux and also for other platforms when the platform specific version is not present.

Finally install KQCircuits itself in editable mode and without dependencies, as they are already present:

pip install --no-deps -e .

or from the top level:

pip install --no-deps -e klayout_package/python/

PyPI Installation

If you do not need all KQCircuits sources but only the core KQC classes you may simply run pip install kqcircuits to get the Python package only. You can use this the same way as the full developer installation but remember that scripts, masks, documentation and notebooks are not part of the Python package. A new Python package is automatically uploaded to PyPI for every tagged commit in GitHub.

The kqcircuits Python package may be used with an independently downloaded KQCircuits source directory to run tests, simulation scripts or build documentation or masks from there. You are supposed to run most of these from the source directory or you may need to specify the KQC_ROOT_PATH environment variable so that kqcircuits finds the sources.


The independence from KLayout GUI makes it possible to do all development of KQCircuits fully within a Python IDE of your choice. For example, standalone debuggers and automated testing (see Testing) can be done, which would not be possible without the standalone KLayout module.

It is possible to generate masks, run simulation scripts or even the actual simulations on the command line:

python klayout_package/python/scripts/masks/quick_demo.py
python klayout_package/python/scripts/simulations/double_pads_sim.py -q
kqc sim waveguides_sim_compare.py -q

The output of the above commands will be in the automatically created tmp directory. If you desire the outputs elsewhere set the KQC_TMP_PATH environment variable to some other path.

The preferred way to instantiate a drawing environment in standalone mode is with the KLayoutView object:

from kqcircuits.klayout_view import KLayoutView
view = KLayoutView()

This creates the required object structure and has helper methods for inserting cells and exporting images. See the KLayoutView API documentation for more details.


The user must keep a reference to the KLayoutView instance in scope, as long as references to the layout or individual cells are used.

Jupyter notebook usage

There is an example Jupyter notebook KQCircuits-Examples/notebooks/viewer.ipynb in the notebooks folder, which shows how to create and visualize KQCircuits elements with the standalone KLayout module. Run it like:

jupyter-notebook notebooks/viewer.ipynb

Updating the required dependencies

Don’t do it unless absolutely necessary! The security model (TOFU) works best if dependencies are rarely changed. When updating dependencies try to verify that the new versions are legitimate.

Edit the *requirements.in files according to your needs. Try to keep >=, <= and == version constraints to a minimum. Try to improve other dependencies too, not only the ones your need.

Compile the new *requirements.txt files:

pip-compile --generate-hashes requirements.in > requirements.txt
pip-compile --generate-hashes doc-requirements.in > doc-requirements.txt

You’ll need to compile the Windows and Mac versions too. If they are different from the common (Linux) versions then remember to commit those files too.