Stimulated Raman adiabatic passage in Optomechanics

Stimulated Raman adiabatic passage (STIRAP) is a well-established technique with applications in atomic physics, trapped-ion physics, superconducting circuits, other solid-state systems, optics, in entanglement generation and qubit operations. Here we demonstrate STIRAP between two vibrational modes of a transparent membrane with highly disparate frequencies in an optical cavity, where by adiabatic following of the optomechanical dark state the excitation of one mechanical mode is coherently transfered to another mechanical mode without population of the optical mode. The maximum state transfer efficiency of a coherent excitation we achieve is 85% which is in good agreement with a theoretical model. The technicque is shown theoretically to work in the quantum regime. This paves the way to entanglement of massive mechanical oscillators and efficient storage of quantum states in long-lived mechanical modes.