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Qualtran

Qᴜᴀʟᴛʀᴀɴ is a Python library for expressing and analyzing Fault Tolerant Quantum algorithms.

From quantumlib·Updated June 16, 2026·View on GitHub·

Python package for fault-tolerant quantum algorithms research. The project is written primarily in Python, distributed under the Apache License 2.0 license, first published in 2022. Key topics include: algorithms, api, cirq, conversion, google.

Latest release: v0.7.0Qualtran v0.7
January 22, 2026View Changelog →
<!-- # Qualtran (title omitted because our logo acts as the title) --> <div align="center"> <img alt="Qualtran logo" width="340px" src="https://raw.githubusercontent.com/quantumlib/Qualtran/refs/heads/main/docs/_static/qualtran-logo-mode-sensitive.svg"> <br>

Python package for fault-tolerant quantum algorithms research.

Licensed under the Apache 2.0 open-source license
Compatible with Python versions 3.12 and higher
Qualtran project on PyPI

Installation
Usage
Documentation
Community
Citation
Contact

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Qualtran is a set of abstractions for representing quantum programs and a library of quantum
algorithms expressed in that language to support quantum algorithms research.

Installation

Qualtran is being actively developed. We recommend installing from the source code.

The following commands will clone a copy of the repository, then install the Qualtran package in
your local Python environment as a local editable copy:

shell
git clone https://github.com/quantumlib/Qualtran.git cd Qualtran/ pip install -e .

You can also install the latest tagged release using pip:

shell
pip install qualtran

You can also install the latest version of the main branch on GitHub:

shell
pip install git+https://github.com/quantumlib/Qualtran

Usage

[!WARNING]
Qualtran is an experimental preview release. We provide no backwards compatibility guarantees.
Some algorithms or library functionality may be incomplete or contain inaccuracies. Open issues or
contact the authors with bug reports or feedback.

You should be able to import the qualtran package into your interactive Python environment as
as well as your programs:

shell
import qualtran

If this is successful, you can move on to learning how to
write bloqs or investigate
the bloqs library.

Documentation

Documentation is available at https://qualtran.readthedocs.io/.

Community

Qualtran's community is growing rapidly, and if you'd like to join the many open-source
contributors
to the Qualtran project, we welcome your participation! We are dedicated to
cultivating an open and inclusive community, and have a code of conduct.

Announcements

You can stay on top of Qualtran news using the approach that best suits your needs:

Questions and Discussions

  • If you'd like to ask questions and participate in discussions, join the qualtran-dev
    group/mailing list. By joining qualtran-dev, you will also get automated invites to the
    biweekly Qualtran Sync meeting (below).

  • Would you like to get more involved in Qualtran development? The biweekly Qualtran Sync
    is a virtual face-to-face meeting of contributors to discuss everything from issues to
    ongoing efforts, as well as to ask questions. Become a member of qualtran-dev to get
    an automatic meeting invitation!

Issues and Pull Requests

Citation<a name="how-to-cite"></a>

When publishing articles or otherwise writing about Qualtran, please cite the following:

bibtex
@misc{harrigan2024qualtran, title={Expressing and Analyzing Quantum Algorithms with Qualtran}, author={Matthew P. Harrigan and Tanuj Khattar and Charles Yuan and Anurudh Peduri and Noureldin Yosri and Fionn D. Malone and Ryan Babbush and Nicholas C. Rubin}, year={2024}, eprint={2409.04643}, archivePrefix={arXiv}, primaryClass={quant-ph}, doi={10.48550/arXiv.2409.04643}, url={https://arxiv.org/abs/2409.04643}, }

Contact

For any questions or concerns not addressed here, please email quantum-oss-maintainers@google.com.

Disclaimer

This is not an officially supported Google product.
This project is not eligible for the Google Open Source Software Vulnerability Rewards
Program
.

Copyright 2025 Google LLC.

<div align="center"> <a href="https://quantumai.google"> <img width="15%" alt="Google Quantum AI" src="https://raw.githubusercontent.com/quantumlib/Qualtran/refs/heads/main/docs/_static/quantum-ai-vertical.svg"> </a> </div>

Contributors

Showing top 12 contributors by commit count.

View all contributors on GitHub →

This article is auto-generated from quantumlib/Qualtran via the GitHub API.Last fetched: 6/17/2026