Raman transitions in ultracold 85Rb by chirped nanosecond-time-scale pulses

Ultracold alkali atoms have been conventionally used for quantum operations. Previously it has been shown theoretically that a single nanosecond, linearly chirped pulse may be implemented to perform population inversion in hyperfine levels of 5S shell in Rb [1]. Here, within a rigorous semiclassical model that involves all optically allowed transitions between hyperfine states of D1 and D2 lines in the $^{85}$Rb atom, we demonstrate a possibility of controlled population transfer using pulses having the duration from one to a few nanoseconds and chirped to induce Raman transitions in the hyperfine state manifold. Experimentally the chirping of nanosecond pulses may be performed in the time domain using fiber-based electro-optical modulators [2]. We will discuss the role of the chirp rate, the pulse duration and the field intensity as control parameters.\\[4pt] [1] T. A. Collins, S. A. Malinovskaya, {\em Opt. Lett.} {\bf 37,} 2298-2300 (2012).\\[0pt] [2] Rogers III, C.E., Wright, M.J., Carini, J.L., Pechkis, J.A., Gould, P.L., {\em J. Opt. Soc. Am. B} {\bf 24,} 1249-1253 (2007).