  The time-dependent Schrodinger equation (TDSE) is usually treated in real
space in the textbook. However, it makes the numerical simulations of
strong-field processes difficult due to the wide dispersion and fast
oscillation of the electron wave packets under the interaction of intense laser
fields. Here we demonstrate that the TDSE can be efficiently solved in the
momentum space. The high-order harmonic generation and above-threshold
ionization spectra obtained by numerical solutions of TDSE in momentum space
agree well with previous studies in real space, but significantly reducing the
computation cost.
