Stark-chirped rapid adiabatic passage among a three-state molecular system: Experimental and numerical investigations

Abstract

We present extended experimental investigations and numerical studies on coherently driven population inversion in a three-state molecular quantum system by sequential double-Stark-chirped rapid adiabatic passage ͑SCRAP͒ ͑D-SCRAP͒ and three-state-SCRAP ͑T-SCRAP͒. D-SCRAP and T-SCRAP are alternative extensions of SCRAP. In D-SCRAP and T-SCRAP, a ⌳-type quantum system is coherently driven by two laser pulses, the pump and Stokes pulses, which are slightly detuned from transition frequencies. A third strong laser pulse induces dynamic Stark shifts of the relevant transitions. If the timing of the three pulses is appropriately chosen, the quantum system is prepared to almost complete population inversion between the two lower states in the ⌳-type level scheme. The transfer process is robust with regard to fluctuations of experimental parameters, provided some limitations are met. The paper presents convincing experimental data on D-SCRAP and T-SCRAP, driving efficient and selective population transfer to a highly excited vibrational level in nitrous oxide ͑NO͒ molecules. T-SCRAP yields transfer efficiencies of up to 95%. The efficiency of T-SCRAP is almost uneffected by the limited lifetime of the intermediate state in the ⌳ system. The paper also presents data on the accurate experimental determination of Rabi frequencies and Stark shifts. This involves measurements of power broadening, Autler-Townes splittings, and Stark-shifted spectral lines in NO molecules. Moreover, we discuss the calibration of absolute transfer efficiences by comparison with stimulated emission pumping. The experimental data are confirmed by extended numerical simulations. The simulations also serve to intensively study the properties and dynamics of D-SCRAP and T-SCRAP.

Optical preparation of H2 rovibrational levels with almost complete population transfer

“…One way to overcome this problem is to transfer population between quantum states using adiabatic passage. Previously stimulated Raman adiabatic passage (STIRAP) [6][7][8][9] and Starkchirped rapid adiabatic passage (SCRAP) [10][11][12][13][14][15] processes were utilized to transfer nearly the complete population between an initial and a target quantum state. However, for the purpose of transferring population between two rovibrational levels within the ground electronic surface of a molecule, both these techniques require a suitable resonant, or near resonant intermediate vibronic state connecting the initial and final (target) rovibrational levels.…”

Can stimulated Raman pumping cause large population transfers in isolated molecules?

“…The later may be accomplished by using an additional off-resonant Stark pulse that sweeps the detuning of the vibrational resonance through zero during the interaction with a relatively weak resonant infrared pump pulse. This approach is similar to what Bergmann and co-workers [39][40][41] introduced for Stark chirped rapid adiabatic passage known as SCRAP, which accomplishes population transfer between two metastable vibrational levels via an intermediate level within the excited electronic manifold. For many molecules therefore, SCRAP requires tunable UV or VUV pulses, making it technically difficult to achieve in practice.…”

Adiabatically driven frequency conversion towards short extreme-ultraviolet radiation pulses

“…In particular, here we mention experimental work by Harris and co-workers [8,10], Marangos and co-workers [15][16][17][18][19], as well as by our own team [3,[18][19][20]. Several adiabatic passage processes [e.g., electromagnetically induced transparency (EIT) [21][22][23] or Stark-chirped rapid adiabatic passage (SCRAP) [24][25][26]] were applied to drive a medium to a state of maximal coherence, followed by efficient frequency mixing. However, adiabatic passage processes are typically implemented with rather long, nanosecond (ns) laser pulses.…”