Robust switching of superposition-states via a coherent double stimulated Raman adiabatic passage

Abstract

Coherent manipulation of quantum states is of crucial importance in accurate control of a quantum system. A fundamental goal is coherently transferring the population of a desired state with near-unit fidelity. For this propose, we theoretically demonstrate a novel coherent double-stimulated Raman adiabatic passage (STIRAP) in a three-level Λ-type system for realizing the switch of unequal initial preparations on two ground states. This operation uses single optical pulse sequence accomplishing both bright-STIRAP and dark-STIRAP process, in which the intermediate-level detuning and the pulse delay must be given an optimal adjustment. Besides, owing to the imperfection of double-STIRAP transition, the sensitivity of the switch fidelity with respect to the spontaneous loss from the intermediate state, to the pulse amplitude and to the population difference, are also discussed. This work suggests a simple and experimentally-feasible all-optical approach to switch the superposition quantum state, serving as one-step closer to the goal of coherent manipulation of quantum systems.

Robust two-state swap by stimulated Raman adiabatic passage

“…by combining them with composite pulses, similarly to the design robust adiabatic pulses in two-state systems. We note that previous work [25] has also discussed exchanging the populations of two ground states in a three-level system by STIRAP but it required very careful adjustment of the single-photon detuning and pulse delay for achieving high fidelity. In contrast, our work (1) demonstrates that swapping is possible for a wide range of the single-photon detuning as long as adiabaticity is maintained, (2) it considers swapping the populations of coherent superposition states and statistical mixtures and the differences between these cases, and (3) it shows that while single STIRAP is sensitive to the dynamic phase η ± (see equation ( 12)), it can be applicable for spin refocusing by , e.g.…”