  In quantum metrology, semiconductor single-electron pumps are used to
generate accurate electric currents with the ultimate goal of implementing the
emerging quantum standard of the ampere. Pumps based on electrostatically
defined tunable quantum dots (QDs) have thus far shown the most promising
performance in combining fast and accurate charge transfer. However, at
frequencies exceeding approximately 1 GHz, the accuracy typically decreases.
Recently, hybrid pumps based on QDs coupled to trap states have led to
increased transfer rates due to tighter electrostatic confinement. Here, we
operate a hybrid electron pump in silicon obtained by coupling a QD to multiple
parasitic states, and achieve robust current quantization up to a few
gigahertz. We show that the fidelity of the electron capture depends on the
sequence in which the parasitic states become available for loading, resulting
in distinctive frequency dependent features in the pumped current.
