Quantum Control of 2+1 Photon Process in Sodium

We demonstrate ultrafast coherent control of multiphoton absorption in a dynamically shifted energy level structure. In a three-level system that models optical interactions with sodium atoms, we control the quantum interference of sequential 2 + 1 photons and direct threephoton transitions. Dynamic change in energy levels predicts an enormous enhancement of |7p�-state excitation in the strong-field regime by a negatively chirped pulse. In addition, the |4s�-state excitation is enhanced symmetrically by nonzero linear chirp rates given as a function of laser peak intensity and laser detuning. Experiments performed by ultrafast shaped-pulse excitation of ground-state atomic sodium verifies the various strong-field contributions to |3s�-|7p� and |3s�-|4s� transitions. The result suggests that for systems of molecular level understanding adiabatic control approach with analytically shaped pulses becomes a more direct control than feedback-loop black-box approaches.

Sangkyung Lee, Jongseok Lim, Chang Yong Park, and Jaewook Ahn, "Strong-field coherent control of 2+1 photon process in atomic sodium," Optics Express 19, 2266-2277 (Jan. 24, 2011). Media:SangkyungOE2011.pdf