  Electron-hole pairs can be excited coherently in a quantum conductor by
applying voltage pulses on its contact. We find that these electron-hole pairs
can be classified into two kinds, whose excitation probabilities have different
dependence on the Faraday flux of the pulse. Most of the pairs are of the first
kind, which can be referred to as "normal" pairs. Their excitation
probabilities increase nearly monotonically with the flux and saturate to the
maximum value 1 when the flux is large enough. In contrast, there exist
"abnormal" pairs, whose excitation probabilities can exhibit oscillations with
the flux. These pairs can only be excited by pulses with small width. Due to
the oscillation of the probabilities, the abnormal pairs can lead to different
features in the full counting statistics of the electron-hole pairs for pulses
with integer and noninteger fluxes.
