Noise Mitigation with Delay Pulses in the IBM Quantum Experience
One of the greatest challenges for current quantum computing hardware is how
to obtain reliable results from noisy devices. A recent paper [A. Kandala et
al., Nature 567, 491 (2019)] described a method for injecting noise by
stretching gate times, enabling the calculation of quantum expectation values
as a function of the amount of noise in the IBM-Q devices. Extrapolating to
zero noise led to excellent agreement with exact results. Here an alternative
scheme is described that employs the intentional addition of identity pulses,
pausing the device periodically in order to gradually subject the quantum
computation to increased levels of noise. The scheme is implemented in a one
qubit circuit on an IBM-Q device. It is determined that this is an effective
method for controlled addition of noise, and further, that using noisy results
to perform extrapolation can lead to improvements in the final output, provided
careful attention is paid to how the extrapolation is carried out.
Sam Tomkins Rogério de Sousa