Formation of ultrashort pulses via quantum interference between Stark-split atomic transitions in a hydrogenlike medium

We derive the analytical solution uncovering the origin of the ultrashort pulse formation from the resonant radiation in a hydrogenlike medium [Y. V. Radeonychev, V. A. Polovinkin, and O. Kocharovskaya, Phys. Rev. Lett. 105, 183902 (2010)], which is a quantum interference of the atomic transitions from the ground to the first excited energy level split by an intense far-off-resonant laser field due to the instantaneous Stark effect into the periodically oscillating sublevels and interference of the resonantly scattered radiation with the incident one. The analytical solution shows that the pulses are almost bandwidth limited and can be produced in a wide range of parameters in excellent agreement with the more general numerical simulation. The experimental schemes to form few-femtosecond pulses from 122-nm radiation in atomic hydrogen as well as few-hundred-attosecond pulses from 13.74-nm radiation in a Li2+ medium are discussed.