Accurate accumulation of arbitrary Berry phases via fractional stimulated Raman adiabatic passage

We propose and analyze a feasible scheme for achieving arbitrary geometric Berry phases based on the efficient technique of fractional stimulated Raman adiabatic passage (f-STIRAP). In a typical Λ   system, we show that a combination of two reversed f-STIRAP processes may result in a preselected coherent superposition of two ground states at the middle time and a desired geometric Berry phase of one dark state at the final time. A most important controlling parameter is the mixing angle of pump and Stokes pulses, which can be accurately designed before the dynamic evolution when we adopt a circularly polarized field and an elliptically polarized field on the J=1↔J′=0J=1↔J′=0 transition. The accurate accumulation of arbitrary Berry phases is of interest, e.g., in quantum computation because it allows the construction of a few quantum gates.