Table of Contents
- Introduction
- Importance of Licensing in Quantum Software
- Common Open-Source Licenses in Quantum Projects
- MIT License: Simplicity and Freedom
- Apache 2.0: Modern, Enterprise-Friendly Licensing
- BSD 3-Clause and 2-Clause Licenses
- GNU GPL and LGPL: Copyleft Implications
- Creative Commons and Documentation Licensing
- Dual Licensing Models in Quantum Ecosystems
- Commercial vs Academic Use Cases
- License Compatibility in Hybrid Quantum Projects
- Implications for Cloud Quantum SDKs
- Attribution and Citation Requirements
- Contribution Agreements and CLA Use
- License Best Practices for Quantum Startups
- Licensing Pitfalls to Avoid
- Selecting a License for Your Quantum Project
- Adding a LICENSE File and Notice
- Handling Third-Party Dependencies
- Conclusion
1. Introduction
Licensing is a critical but often overlooked part of building, distributing, and collaborating on quantum software. It governs how code can be used, modified, and shared.
2. Importance of Licensing in Quantum Software
- Protects intellectual property (IP)
- Clarifies reuse and redistribution terms
- Encourages trust and community engagement
3. Common Open-Source Licenses in Quantum Projects
- Qiskit: Apache 2.0
- PennyLane: Apache 2.0
- Cirq: Apache 2.0
- QuTiP: BSD
- Strawberry Fields: Apache 2.0
4. MIT License: Simplicity and Freedom
- Very permissive
- Minimal conditions
- Ideal for small tools and demos
5. Apache 2.0: Modern, Enterprise-Friendly Licensing
- Explicit patent rights
- Strong legal protection
- Used by most major quantum SDKs
6. BSD 3-Clause and 2-Clause Licenses
- Academic origin
- More permissive than GPL
- Minimal legal overhead
7. GNU GPL and LGPL: Copyleft Implications
- Requires derived works to use same license
- Less common in quantum, but used in scientific toolkits
8. Creative Commons and Documentation Licensing
- CC-BY or CC-BY-SA for docs, books, tutorials
- Not suited for software code
9. Dual Licensing Models in Quantum Ecosystems
- Open-source + commercial license
- Example: use open-source for research, paid for enterprise support
10. Commercial vs Academic Use Cases
- Many licenses allow academic use freely
- Commercial integrations may need license review
11. License Compatibility in Hybrid Quantum Projects
- Ensure code combining Qiskit + Cirq + PennyLane doesn’t conflict
- Prefer permissive licenses to maximize compatibility
12. Implications for Cloud Quantum SDKs
- SDKs are open-source, but cloud APIs may have usage restrictions
- Always separate API tokens and follow provider ToS
13. Attribution and Citation Requirements
- Apache 2.0 and BSD recommend including license and attribution
- Scientific papers may also request citation of software
14. Contribution Agreements and CLA Use
- Contributor License Agreement (CLA): defines IP rights
- Used by larger projects like Qiskit to protect codebase integrity
15. License Best Practices for Quantum Startups
- Start with permissive license (MIT or Apache)
- Add clear NOTICE and LICENSE files
- Plan for dual license if offering SaaS or enterprise tiers
16. Licensing Pitfalls to Avoid
- Mixing incompatible licenses (e.g., GPL with proprietary code)
- Forgetting to include license headers
- Using code snippets without attribution
17. Selecting a License for Your Quantum Project
- Use tools like https://choosealicense.com
- Consider use cases: research, teaching, commercial
18. Adding a LICENSE File and Notice
- Use GitHub templates
- Include license header in each file if required
19. Handling Third-Party Dependencies
- Audit dependencies with
pip-licensesorlicense-checker - Document licenses in README or setup scripts
20. Conclusion
Licensing is foundational to collaboration and sustainability in quantum software. By choosing the right license, honoring compatibility, and maintaining clarity, quantum developers and organizations can foster trust and accelerate global innovation.
