# pgdb_process_estimate¶

forest.benchmarking.tomography.pgdb_process_estimate(results: List[forest.benchmarking.observable_estimation.ExperimentResult], qubits: List[int], trace_preserving=True) → numpy.ndarray

Provide an estimate of the process via Projected Gradient Descent with Backtracking [PGD].

 [PGD] Maximum-likelihood quantum process tomography via projected gradient descent. Knee et al. Phys. Rev. A 98, 062336 (2018). https://dx.doi.org/10.1103/PhysRevA.98.062336 https://arxiv.org/abs/1803.10062
Parameters: results – A tomographically complete list of ExperimentResults qubits – A list of qubits giving the tensor order of the resulting Choi matrix. trace_preserving – Whether to project the estimate to a trace-preserving process. If set to False, we ensure trace non-increasing. an estimate of the process in the Choi matrix representation.