We are committed to make our research software available to other researchers with minimal limitations and hope to motivate some to help improving it. However, economic and strategic interests are becoming increasingly influential in the field of quantum computing. We have therefore chosen the copyleft GPL license to prevent an uncontrolled incorporation in proprietary software packages. However, to facilitate a potential future use in a commercial context, we would like to retain the possibility to offer the software packages developed under our lead under a different license. As this requires control of the copyright, we may ask contributors to execute a copyright assignment agreement. Following common practice, this agreement will license back all relevant rights of contributors regarding their contributions. We feel that this is a fair arrangement at least for minor contributions.
We hope that this strategy will not be a barrier to using the software at hand or to contributing to its advancement. If it does, please do not hesitate to contact us to consider alternative approaches.