# Cirq

> free software library for editing and simulating quantum circuits

**Wikidata**: [Q65079041](https://www.wikidata.org/wiki/Q65079041)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Cirq)  
**Source**: https://4ort.xyz/entity/cirq

## Summary
Cirq is a free, open-source Python library developed by Google's Quantum AI team for designing and simulating quantum circuits. It enables researchers and developers to experiment with quantum algorithms and near-term quantum computing hardware. Released under the Apache 2.0 license, Cirq provides tools for creating, editing, and simulating quantum programs.

## Key Facts
- **Initial Release**: April 17, 2018 (version 0.1).
- **Latest Version**: 0.14.0 (released March 24, 2022).
- **Programming Language**: Built for Python.
- **License**: Apache Software License 2.0.
- **Developer**: Google's Quantum AI team.
- **Repository**: Hosted on GitHub at [https://github.com/quantumlib/Cirq](https://github.com/quantumlib/Cirq).
- **Announcement**: Publicly announced on July 18, 2018, via Google's AI blog.

## FAQs
### Q: What programming language is Cirq written in?
A: Cirq is built for Python, leveraging its flexibility for quantum circuit development.

### Q: Is Cirq free to use?
A: Yes, Cirq is free and open-source under the Apache 2.0 license, allowing unrestricted use and modification.

### Q: Who developed Cirq?
A: Cirq was created by Google's Quantum AI team to support research in quantum computing.

## Why It Matters
Cirq plays a critical role in advancing quantum computing by providing accessible tools for designing and simulating quantum circuits. As quantum technology evolves, Cirq helps researchers and developers prototype algorithms and test them on near-term quantum hardware. Its open-source nature fosters collaboration, while Google's backing ensures alignment with industry standards. By simplifying quantum programming, Cirq lowers barriers to entry for both academia and industry, accelerating innovation in the field.

## Notable For
- Developed by Google's Quantum AI team, ensuring integration with leading quantum research.
- Focuses on near-term quantum computing, emphasizing practical hardware constraints.
- Offers high flexibility for customizing quantum operations and simulating noise models.
- Released under the permissive Apache 2.0 license, encouraging community adoption and contribution.

## Body
### Overview
Cirq is a Python-based framework for quantum computing, designed to bridge the gap between theoretical quantum algorithms and real-world hardware. It allows users to define quantum circuits, simulate their behavior, and optimize performance for near-term devices.

### Development and Release History
- **First Release**: Version 0.1 debuted on April 17, 2018, introducing core functionality for quantum circuit construction.
- **Public Announcement**: Google unveiled Cirq on July 18, 2018, highlighting its role in democratizing quantum research.
- **Key Updates**:
  - **Version 0.8.0 (May 4, 2020)**: Added support for quantum error correction and improved simulation tools.
  - **Version 0.14.0 (March 24, 2022)**: Enhanced compatibility with modern quantum processors and expanded documentation.

### Key Features
- **Python Integration**: Leverages Python's simplicity for rapid prototyping of quantum algorithms.
- **Hardware-Aware Design**: Simulates noise and gate constraints of real quantum processors.
- **Modular Architecture**: Supports customization of quantum gates, operations, and measurement protocols.

### Licensing and Accessibility
Cirq is freely available under the Apache 2.0 license, permitting commercial and academic use. Its source code is hosted on GitHub, and binaries are distributed via PyPI (Python Package Index) under the name `cirq`.

### Community and Support
- **Mailing List**: Users and developers engage via the [Cirq-announce](https://groups.google.com/forum/#!forum/cirq-announce) Google Group.
- **Documentation**: Tutorials and API references are maintained on Google's Quantum AI website.

## References

1. [2022](https://github.com/quantumlib/Cirq/releases/tag/v0.14.0)
2. [Cirq V0.14 release. 2022](https://groups.google.com/g/cirq-announce/c/X68TcTzZIow)
3. [Release 0.1. 2018](https://github.com/quantumlib/Cirq/releases/tag/v0.1)
4. [Release 0.3.1. 2018](https://github.com/quantumlib/Cirq/releases/tag/v0.3.1)
5. [Release 0.4.0. 2018](https://github.com/quantumlib/Cirq/releases/tag/v0.4.0)
6. [Release 0.5.0. 2019](https://github.com/quantumlib/Cirq/releases/tag/v0.5.0)
7. [Release 0.6.0. 2019](https://github.com/quantumlib/Cirq/releases/tag/v0.6.0)
8. [Release 0.7.0. 2020](https://github.com/quantumlib/Cirq/releases/tag/v0.7.0)
9. [Release 0.8.0. 2020](https://github.com/quantumlib/Cirq/releases/tag/v0.8.0)
10. [Release 0.8.1. 2020](https://github.com/quantumlib/Cirq/releases/tag/v0.8.1)
11. [Release 0.8.2. 2020](https://github.com/quantumlib/Cirq/releases/tag/v0.8.2)
12. [Release 0.9.0. 2020](https://github.com/quantumlib/Cirq/releases/tag/v0.9.0)
13. [Release 0.9.1. 2020](https://github.com/quantumlib/Cirq/releases/tag/v0.9.1)
14. [Release 0.10.0. 2021](https://github.com/quantumlib/Cirq/releases/tag/v0.10.0)
15. [Release 0.11.0. 2021](https://github.com/quantumlib/Cirq/releases/tag/v0.11.0)
16. [Release 0.11.1. 2021](https://github.com/quantumlib/Cirq/releases/tag/v0.11.1)
17. [Release 0.12.0. 2021](https://github.com/quantumlib/Cirq/releases/tag/v0.12.0)
18. [Release 0.13.0. 2021](https://github.com/quantumlib/Cirq/releases/tag/v0.13.0)
19. [Release 0.13.1. 2021](https://github.com/quantumlib/Cirq/releases/tag/v0.13.1)
20. [Release 0.14.1. 2022](https://github.com/quantumlib/Cirq/releases/tag/v0.14.1)
21. [Release 0.15.0. 2022](https://github.com/quantumlib/Cirq/releases/tag/v0.15.0)
22. [Release 1.0.0. 2022](https://github.com/quantumlib/Cirq/releases/tag/v1.0.0)
23. [Release 1.1.0. 2022](https://github.com/quantumlib/Cirq/releases/tag/v1.1.0)
24. [Release 1.2.0. 2023](https://github.com/quantumlib/Cirq/releases/tag/v1.2.0)
25. [Release 1.3.0. 2023](https://github.com/quantumlib/Cirq/releases/tag/v1.3.0)
26. [Release 1.4.0. 2024](https://github.com/quantumlib/Cirq/releases/tag/v1.4.0)
27. [Release 1.4.1. 2024](https://github.com/quantumlib/Cirq/releases/tag/v1.4.1)
28. [Release 1.5.0. 2025](https://github.com/quantumlib/Cirq/releases/tag/v1.5.0)
29. [Release 1.6.0. 2025](https://github.com/quantumlib/Cirq/releases/tag/v1.6.0)
30. [Release 1.6.1. 2025](https://github.com/quantumlib/Cirq/releases/tag/v1.6.1)
31. [Source](https://ai.googleblog.com/2018/07/announcing-cirq-open-source-framework.html)