  The role of the Coulomb potential on the generation of elliptically polarized
high-order harmonics from atoms driven by elliptically polarized laser is
investigated analytically. It is found that the Coulomb effect makes a
contribution to the harmonic ellipticity for low harmonic orders and short
quantum path. By using the strong-field eikonal-Volkov approximation, we
analyze the influence of the Coulomb potential on the dynamics of the continuum
state and find that the obtained harmonic ellipticity in our simulation
originates from the break of symmetry of the continuum state.
