Highly Efficient Creation and Detection of Ultracold Deeply-Bound Molecules via Chainwise Stimulated Raman Shortcut-to-Adiabatic Passage

Chainwise stimulated Raman adiabatic passage (C-STIRAP) in M-type molecularsystem is a good alternative in creating ultracold deeply-bound molecules whenthe typical STIRAP in {\Lambda}-type system does not work due to weakFrank-Condon factors between states. However, its creation efficiency under thesmooth evolution is generally low. During the process, the population in theintermediate states may decay out quickly and the strong laser pulses mayinduce multi-photon processes. In this paper, we find thatshortcut-to-adiabatic (STA) passage fits very well in improving the performanceof the C-STIRAP. Currently, related discussions on the so-called chainwisestimulated Raman shortcut-to-adiabatic passage (C-STIRSAP) are rare. Here, weinvestigate this topic under the adiabatic elimination. Given a relation amongthe four incident pulses, it is quite interesting that the M-type system can begeneralized into an effective {\Lambda}-type structure with the simplestresonant coupling. Consequently, all possible methods of STA for three-statesystem can be borrowed. We take the counter-diabatic driving and "chosen path"method as instances to demonstrate our treatment on the molecular system.Although the "chosen path" method does not work well in real three-state systemif there is strong decay in the excited state, our C-STIRSAP protocol underboth the two methods can create ultracold deeply-bound molecules with highefficiency in the M-type system. The evolution time is shortened without stronglaser pulses and the robustness of STA is well preserved. Finally, thedetection of ultracold deeply-bound molecules is discussed.