When should I use ZNE?#
Zero noise extrapolation is one of the simplest error mitigation techniques and, in many practical situations, it can be applied with a relatively small sampling cost. The main advantage of ZNE is that the technique can be applied without a detailed knowledge of the undelying noise model. Therefore it can be a good option in situations where tomography is impractical.
In some instances the results of the extrapolation can exhibit a large bias . ZNE may not be helpful in cases where a low degree polynomial curve obtained by fitting the noisy expectation values does not match the zero-noise limit. When using circuits of less trivial depth on real devices, the lowest error points may be too noisy for the extrapolation to show improvement over the unmitigated result .
For a simple example in which the application of ZNE reduces the estimation error when compared to the unmitigated result, see: