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OpenFermion is an open source effort for compiling and analyzing quantum algorithms to simulate fermionic systems, including quantum chemistry. Among other functionalities, the current version features data structures and tools for obtaining and manipulating representations of fermionic and qubit Hamiltonians. For more information, see our release paper. Documentation Status

Getting started

Installing OpenFermion requires pip. Make sure that you are using an up-to-date version of it. For information about getting started beyond what is provided below please see intro and code examples. Also take a look at the ipython notebook demo as well as our detailed code documentation.

Currently, OpenFermion is only tested on Mac and Linux for the reason that both electronic structure plugins are only compatible with Mac and Linux. However, for those who would like to use Windows, or for anyone having other difficulties with installing OpenFermion or its plugins, we have provided a Docker image and usage instructions in the docker folder. The Docker image provides a virtual environment with OpenFermion and select plugins pre-installed. The Docker installation should run on any operating system.

You might also want to explore the alpha release of the OpenFermion Cloud Library where users can share and download precomputed molecular benchmark files.

Developer install

To install the latest version of OpenFermion (in development mode):

git clone
cd OpenFermion
python -m pip install -e .

Library install

To install the latest PyPI release as a library (in user mode):

python -m pip install --user openfermion


OpenFermion relies on modular plugin libraries for significant functionality. Specifically, plugins are used to simulate and compile quantum circuits and to perform classical electronic structure calculations. Follow the links below to learn more about these useful plugins.

Circuit compilation and simulation plugins

Electronic structure package plugins

How to contribute

We'd love to accept your contributions and patches to OpenFermion. There are a few small guidelines you need to follow. Contributions to OpenFermion must be accompanied by a Contributor License Agreement. You (or your employer) retain the copyright to your contribution, this simply gives us permission to use and redistribute your contributions as part of the project. Head over to to see your current agreements on file or to sign a new one.

All submissions, including submissions by project members, require review. We use GitHub pull requests for this purpose. Consult GitHub Help for more information on using pull requests. Furthermore, please make sure your new code comes with extensive tests! We use automatic testing to make sure all pull requests pass tests and do not decrease overall test coverage by too much. Make sure you adhere to our style guide. Just have a look at our code for clues. We mostly follow PEP 8 and use the corresponding linter to check for it. Code should always come with documentation, which is generated automatically and can be found here.


Ryan Babbush (Google), Jarrod McClean (Google), Ian Kivlichan (Harvard), Kevin J. Sung (University of Michigan), Damian Steiger (ETH Zurich), Dave Bacon (Google), Yudong Cao (Harvard), Chengyu Dai (University of Michigan), E. Schuyler Fried (Harvard), Craig Gidney (Google), Brendan Gimby (University of Michigan), Thomas Häner (ETH Zurich), Tarini Hardikar (Dartmouth), Vojtĕch Havlíček (Oxford), Cupjin Huang (University of Michigan), Zhang Jiang (NASA), Thomas O'Brien (Leiden University), Isil Ozfidan (D-Wave Systems), Matthew Neeley (Google), Max Radin (UC Santa Barbara), Jhonathan Romero (Harvard), Nicholas Rubin (Rigetti), Daniel Sank (Google), Nicolas Sawaya (Harvard), Kanav Setia (Dartmouth), Hannah Sim (Harvard), Mark Steudtner (Leiden University), Qiming Sun (Caltech), Wei Sun (Google) and Fang Zhang (University of Michigan).

How to cite

When using OpenFermion for research projects, please cite:

Jarrod R. McClean, Ian D. Kivlichan, Kevin J. Sung, Damian S. Steiger, Yudong Cao, Chengyu Dai, E. Schuyler Fried, Craig Gidney, Brendan Gimby, Thomas Häner, Tarini Hardikar, Vojtĕch Havlíček, Cupjin Huang, Zhang Jiang, Matthew Neeley, Thomas O'Brien, Isil Ozfidan, Maxwell D. Radin, Jhonathan Romero, Nicholas Rubin, Nicolas P. D. Sawaya, Kanav Setia, Sukin Sim, Mark Steudtner, Wei Sun, Fang Zhang and Ryan Babbush. OpenFermion: The Electronic Structure Package for Quantum Computers. arXiv:1710.07629. 2017.

We are happy to include future contributors as authors on later releases.


Copyright 2017 The OpenFermion Developers. This is not an official Google product.