Robust population transfer in atomic beams induced by Doppler shifts

A. Peralta Conde, Леонід Петрович Яценко, Jens Klein +2 more

We present experimental data to demonstrate coherently driven population inversion by retroreflection-induced bichromatic adiabatic passage in metastable helium atoms. Complete and robust population transfer from an initial to a target state is induced by coherent interaction of the atoms in a supersonic beam with two counterpropagating and temporally delayed laser pulses of different intensities. The radiation fields intersect the atomic beam slightly tilted away from normal incidence, thereby inducing Doppler shifts of the atomic resonance between the initial and the target state. Thus the laser pulses produce a bichromatic field in the rest frame of each atom, which induces complete coherent population transfer by an adiabatic passage process.

D.V. Kolsachjov, Boris G. Matisov, Yu. Rozhdestvensky +2 more

Леонид Петрович Пресняков, Viatcheslav P. Shevelko

Леонід Петрович Яценко, Bruce W. Shore, Nikolay V. Vitanov +1 more

We present a simple technique that can, without the need for frequency-chirped lasers or varying Stark shifts, produce a complete adiabatic passage between two atomic or molecular bound states. The technique uses a single laser beam, which crosses the particle beam slightly tilted away from normal incidence, thereby inducing a controlled Doppler shift. A subsequent retroreflection produces effectively a two-pulse bichromatic field in the rest frame of each particle. The retroreflected beam is parallel to the incident beam, but is slightly offset in space and has a reduced intensity. Using the adiabatic Floquet theory developed recently by Gu\'erin et al. [Phys. Rev. 63, 031403 (2001)] we show that such a field is capable of producing complete and robust population transfer between two quantum states. We derive the conditions for such transfer and illustrate the potential success with model simulations.

Stephen D. Clow, Uvo Holscher, Carlos A Trallero-Herrero +1 more

Andon A. Rangelov, Nikolay V. Vitanov, Леонід Петрович Яценко +3 more

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 minimized, 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.