Estimating fidelity by propagating errors through quantum circuits

As quantum computers continue to develop and advance, the need to be able to predict their performance continues to be important. Current attempts either assume overly simplified error models or aim to describe the error in a dense format, making modeling computationally infeasible. Here, we propose a new method where each gate error can be approximated by the rates of a polynomial number of primitive error generators. These errors can be propagated through a Clifford circuit allowing for us to efficiently generate an error map for the entire circuit to high order. This method captures the transformations individual errors undergo as they interact with gates and other error generators while being scalable to large quantum processors. Additionally, time dependent error rates can be used to capture the behavior of non-Markovian noise. We demonstrate the accuracy of this new method by comparing the predicted end of circuit error generator with the true end of circuit error generator created by propagating process matrices. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.