PennyLane
PennyLane is the flagship open-source Python framework for quantum differentiable programming — train and optimize variational quantum circuits with the same automatic differentiation engines used in classical machine learning. PennyLane unifies quantum machine learning, quantum chemistry, and hybrid quantum-classical workflows behind a single device-abstraction API, interoperates with NumPy, PyTorch, JAX, and TensorFlow/Keras, and runs against 40+ simulators and hardware backends through its plugin ecosystem. Apache 2.0 licensed. 3,200+ GitHub stars.
Documentation
Documentation
https://docs.pennylane.ai/en/stable/
APIReference
https://docs.pennylane.ai/en/stable/code/qml.html