Research On The Efficiency Limitation For Realizing An Atom-molecule Adiabatic Transfer Based On A Chainwise System

How to efficiently produce ultracold molecules has been an important project for scientists in recent years. Molecule has more complicated energy levels than atom due to its extra rotational and vibrational degrees of freedom. Thus obtaining such a class of ultracold molecules would open new possibilities for precision measurements. In the past decades, most physicists investigated the atom-molecule transfer efficiency in three-level A systems. However we need very large pump laser power to make the transition between atomic and molecular states because of the extremely small Franck-Condon (FC) factors. So physicists have proposed a large number of multilevel schemes to prepare ultracold molecules. One question emerges that whether the transfer efficiency will be increasing as more energy levels are included which has not been well discussed yet. In the present work, we consider a generalized chainwise system in which the number of intermediate energy levels is not fixed; By changing the number of intermediate levels,we could study the efficiency limitation with respect to it. We obtain a generalized adiabatic parameter for describing the adiabaticity of chainwise system, and present various optimization approaches to parameters in order to improve the efficiency, involving the order number of system n, relative strength ratio, and absolute strength of intermediate laser. We show that there remains a limit for the population transfer efficiency which is smaller than the results from three-level A systems under same conditions. The reason for that is well presented.