The parameter-shift rule is an approach to measuring gradients of quantum circuits with respect to their parameters, which does not require ancilla qubits or controlled operations. Here, I discuss applying this approach to a wider range of parameterize quantum gates by decomposing gates into a product of standard gates, each of which is parameter-shift rule differentiable.
@article{arxiv.1905.13311,
title = {Gradients of parameterized quantum gates using the parameter-shift rule and gate decomposition},
author = {Gavin E. Crooks},
journal= {arXiv preprint arXiv:1905.13311},
year = {2019}
}