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The electronic structure package for quantum computers.
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xabomon and ncrubin Enhancement of Project onto sector function. (#538)
* Update qubit tapering for stabilizers weight larger than operator, including test

* Update qubit tapering for stabilizers weight larger than operator, including test

* Modify NOTICE, README including myself

* Enhancement of project_onto_sector, update test
Latest commit 3b2b15b Sep 9, 2019
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cloud_library minor typo in cloud docs (#171) Jan 18, 2018
dev_tools/packaging Change EQ_TOLERANCE from 1e-12 to 1e-8 (#487) Nov 14, 2018
docker Update Docker image (#441) Sep 3, 2018
docs added Bayesian PEA paper to projects (#473) Sep 29, 2018
examples Port packaging scripts from Cirq (#486) Nov 14, 2018
src/openfermion Enhancement of Project onto sector function. (#538) Sep 9, 2019
.gitignore add entries to gitignore (#327) May 1, 2018
.travis.yml fixed bug in travis config (#297) Mar 29, 2018
LICENSE OpenFermion v0.1a0 Sep 21, 2017 Test installed module (#376) Jun 26, 2018
NOTICE Update NOTICE (#532) Jul 27, 2019
requirements.txt Lower numpy requirement (#478) Oct 12, 2018 fix image issue on pypi (#400) Jul 18, 2018


OpenFermion is an open source library for compiling and analyzing quantum algorithms to simulate fermionic systems, including quantum chemistry. Among other functionalities, this 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

Run the interactive Jupyter Notebooks on MyBinder:


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!

Circuit compilation and simulation plugins

Electronic structure package plugins

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 our tutorial in the examples folder 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.

Check out other projects and papers using OpenFermion for inspiration, and let us know if you've been using OpenFermion!

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

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.

We use Github issues for tracking requests and bugs. Please post questions to the Quantum Computing Stack Exchange with an 'openfermion' tag.


Ryan Babbush (Google), Jarrod McClean (Google), Kevin Sung (University of Michigan), Ian Kivlichan (Harvard), Dave Bacon (Google), Xavier Bonet-Monroig (Leiden University), Yudong Cao (Harvard), Chengyu Dai (University of Michigan), E. Schuyler Fried (Harvard), Craig Gidney (Google), Brendan Gimby (University of Michigan), Pranav Gokhale (University of Chicago), Thomas Häner (ETH Zurich), Tarini Hardikar (Dartmouth), Vojtĕch Havlíček (Oxford), Oscar Higgott (University College London), Cupjin Huang (University of Michigan), Josh Izaac (Xanadu), Zhang Jiang (NASA), William Kirby (Tufts University), Xinle Liu (Google), Sam McArdle (Oxford), Matthew Neeley (Google), Thomas O'Brien (Leiden University), Bryan O'Gorman (UC Berkeley, NASA), Isil Ozfidan (D-Wave Systems), Max Radin (UC Santa Barbara), Jhonathan Romero (Harvard), Nicholas Rubin (Google), Daniel Sank (Google), Nicolas Sawaya (Harvard), Bruno Senjean (Leiden University), Kanav Setia (Dartmouth), Hannah Sim (Harvard), Damian Steiger (ETH Zurich), Mark Steudtner (Leiden University), Qiming Sun (Caltech), Wei Sun (Google), Daochen Wang (River Lane Research), Chris Winkler (University of Chicago) and Fang Zhang (University of Michigan).

How to cite

When using OpenFermion for research projects, please cite:

Jarrod R. McClean, Kevin J. Sung, Ian D. Kivlichan, Xavier Bonet-Monroig, Yudong Cao, Chengyu Dai, E. Schuyler Fried, Craig Gidney, Brendan Gimby, Pranav Gokhale, Thomas Häner, Tarini Hardikar, Vojtĕch Havlíček, Oscar Higgott, Cupjin Huang, Josh Izaac, Zhang Jiang, William Kirby, Xinle Liu, Sam McArdle, Matthew Neeley, Thomas O'Brien, Bryan O'Gorman, Isil Ozfidan, Maxwell D. Radin, Jhonathan Romero, Nicholas Rubin, Nicolas P. D. Sawaya, Kanav Setia, Sukin Sim, Damian S. Steiger, Mark Steudtner, Qiming Sun, Wei Sun, Daochen Wang, 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.

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