In this paper, we have proposed and
demonstrated a new method of atomic population transfer. The transition dynamic of a two-level system is studied in a full quantum description of the Jaynes-Cummings model. Solving the time-dependent Schrödinger equation, we have investigated the transition probabilities numerically and analytically by using a sudden
boost of the laser frequency. The results show that complete population transfer can be achieved by adjusting the time of the frequency boost.