The observation of above threshold ionization as a benchmark experiment has significantly motivated the progress of strong-field physics. Above threshold ionization is one of the most important processes in strong-field community. The researchers at School of Physics, Peking University have developed an intuitive quantum-trajectory Monte Carlo (QTMC) model encoded with Feynman's path-integral approach based on the tunneling theory, in which the Coulomb effect on electron trajectories and interference patterns are fully considered. They achieved a good agreement with the measured photoelectron angular distributions of atoms for above threshold ionization. The QTMC theory sheds light on the role of ionic potential on photoelectron angular distributions along the longitudinal and transverse direction with respect to the laser polarization, allowing to unravel the classical coordinates (i.e., tunneling phase and initial momentum) at the tunnel exit for all of photoelectrons of photoelectron angular distributions. They have studied the classical-quantum correspondence and build a bridge between the above threshold ionization and the tunneling theory. The paper was published on Physical Review Letters [Min Li et al., Phys. Rev. Lett. 112, 113002(2014)].