Bulg. J. Phys. vol.33 no.s3 (2006), pp. 151-171

Level Crossing in Coherent Atomic Excitation: New Concepts

A.A. Rangelov1, N.V. Vitanov1,2, L.P. Yatsenko3, B.W. Shore4,5, T. Halfmann4, K. Bergmann4
1University of Sofia, 5 James Bourchier Blvd., BG-1164 Sofia, Bulgaria
2Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee Blvd., BG-1784 Sofia, Bulgaria
3Institute of Physics, National Academy of Science of Ukraine, prospect Nauki 46, UA-03650 Kiev, Ukraine
4Fachbereich Physik der Universität, Erwin Schrödinger Str. Gebäude 46, D-67653 Kaiserslautern, Germany
5618 Escondido Circle, Livermore, CA 94550, USA
Abstract. We show that the technique of Stark-chirped rapid adiabatic passage (SCRAP), hitherto used for complete population transfer between two quantum states, offers a simple and robust method for complete population transfer amongst three states in atoms and molecules. In this case SCRAP uses three laser pulses: a strong far-off-resonant pulse modifies the transition frequencies by inducing dynamic Stark shifts and thereby creating time-dependent level crossings amongst the three diabatic states, while near-resonant and moderately strong pump and Stokes pulses, appropriately offset in time, drive the population between the initial and final states via adiabatic passage. The population transfer efficiency is robust to variations in the intensities of the lasers, as long as these intensities are sufficiently large to enforce adiabatic evolution. With suitable pulse timings the population in the (possibly decaying) intermediate state can be minimised, as with stimulated Raman adiabatic passage (STIRAP). This technique applies to one-photon as well as multiphoton transitions and it is also applicable to media exhibiting inhomogeneous broadening; these features represent clear advantages over STIRAP by overcoming the inevitable dynamical Stark shifts that accompany multiphoton transitions as well as unwanted detunings, e.g. induced by Doppler shifts.

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