Heisenberg Echo Symmetrization for Gate-Insertion Error Mitigation
Gate Insertion (GI) error mitigation fails when gate noise doesn't commute with gates. Heisenberg-echo symmetrization (HES) fixes this by combining standard GI with an echo inspired by the Heisenberg representation. This combination cancels the leading error term from non-commuting noise, reducing absolute fidelity error by one to two orders of magnitude while maintaining simplicity.