Hannover 2003 – scientific programme

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Q: Quantenoptik

Q 45: Poster: Laserspektroskopie

Q 45.3: Poster

Thursday, March 27, 2003, 16:30–18:30, Lichthof

Superadiabatic population inversion of a two-state system — •Nikolay Vitanov^1,2, Leonid Yatsenko^1,3 und Klaas Bergmann¹ — ¹Fachbereich Physik der Universitaet, 67653 Kaiserslautern, Germany — ²Theoretical Physics Division, Department of Physics, Sofia University, James Boucher 5 blvd., 1126 Sofia, Bulgaria — ³Institute of Physics, Ukrainian Academy of Sciences, prospect Nauki 46, Kiev-39, 03650, Ukraine

We propose a novel scheme for coherent population inversion of a two-state system based on superadiabatic evolution. A smooth driving external pulsed field is supplemented by a harmonically amplitude-modulated pulse, suitably offset in time with respect to the driving pulse. In the modulation-free adiabatic basis, the modulated pulse introduces oscillating interaction between the adiabatic states. A second rotating-wave approximation shows that this oscillating interaction induces a pair of level crossings between the adiabatic states if the modulation frequency is chosen appropriately. By suitably delaying the modulated pulse with respect to the pump pulse, one can make the modulated pulse act only in the vicinity of one of these crossings. In a superadiabatic basis, this crossing shows up as an avoided crossing between the energies of the superadiabatic states. We derive analytically the conditions on the interaction parameters for the state vector to follow one of the superadiabatic states. Then a robust and efficient superadiabatic population transfer can be achieved between the adiabatic states, as well as between the original bare states.