QSBIT simulator

In fault-tolerant quantum computing, delays in classical control and decoding can stall quantum execution. qsbit-sim provides cycle-level simulation of quantum control systems to help evaluate architectural trade-offs and identify timing bottlenecks before hardware implementation.

The project is inspired by CACTUS, a quantum-control architecture simulator.

Documentation · Examples · Execution player

Note

qsbit-sim is in early development. Its architecture and APIs may change without backward compatibility. Feedback and bug reports are welcome.

Build

Install the prerequisites, prepare the Conan dependencies, then run from the repository root:

cmake --preset clang-ninja
cmake --build --preset clang-ninja --parallel
cmake --install build-clang --prefix "$HOME/.local"
export PATH="$HOME/.local/bin:$PATH"

Run

qsbit-sim --config build-clang/examples/measurement-feedback/mock.json

For quantum-state evolution, configure Aer, Stim or QuTiP.

Replay

Open the execution trace in a browser:

python3 tools/replay_trace.py build-clang/examples/measurement-feedback/mock-results.jsonl

Learn more

• Quickstart: run and inspect both feedback branches.
• Architecture: control, timing and feedback.
• Configuration reference: instructions, profiles and outputs.
• Development: builds, tests and contribution checks.

Citation

If you use qsbit-sim in your work, please cite the software repository:

@misc{qsbit2026sim,
  author       = {{qsbit-sim contributors}},
  title        = {{qsbit-sim}: A quantum-control hardware simulator},
  year         = {2026},
  howpublished = {GitHub repository},
  url          = {https://github.com/qsbit-org/qsbit-sim}
}

References

• An Experimental Microarchitecture for a Superconducting Quantum Processor.
• eQASM: An Executable Quantum Instruction Set Architecture.
• Distributed-HISQ: A Distributed Quantum Control Architecture.

AI Acknowledgement

This project is developed with assistance from AI coding tools, including code generation, refactoring, testing, and documentation. All changes are reviewed and validated by the maintainers, who remain responsible for the project's design, correctness, and quality.

License

Apache License 2.0. Bundled nlohmann/json uses the MIT license.