Stimulated Raman adiabatic passage
In quantum optics, stimulated Raman adiabatic passage (STIRAP) is a process that permits transfer of a population between two applicable quantum states via at least two coherent electromagnetic (light) pulses. These light pulses drive the transitions of the three level Ʌ atom or multilevel system.
Source: Wikipedia — Stimulated Raman adiabatic passage (CC BY-SA 4.0)