Efficient Population Transfer in a Multi-Level Atom

Wei Li, Li-Xiang Cen

Guan-Qiang Li, Yu-Qi Zhang, Hao Guo +3 more

The optimal control of population transfer for multi-level systems is investigated from the perspective of quantum geometry. Firstly, the general theoretical framework of optimizing the stimulated Raman adiabatic passage (STIRAP) scheme based on the dynamical quantum geometric tensor is given, and then the dynamical quantum geometric tensor and the nonadiabatic transition rate are calculated by taking the detuned $Λ$-type three-level system and tripod-type four-level system for example. Secondly, the transfer dynamics of the particle population of the system are investigated in detail. For a three-level system, the optimal STIRAP scheme has an efficiency of over 98\% in transferring the population to the final state, while the transfer efficiency of traditional STIRAP is about 72\%. The superposition states with arbitrary proportions can be efficiently prepared for a four-level system due to the decoupling of the degenerate dark states. Finally, the influences of system parameters, such as the operation time of the Rabi pulses, the amplitude fluctuation and the single-photon detuning, on the transfer process are discussed. Especially, the phenomenon of the adiabatic resonance transfer is revealed. Choosing the pulse parameters in the resonance window can reduce the infidelity of the population transfer to below $10^{-3}$. It is found that the optimal STIRAP scheme by the dynamical quantum geometric tensor provides faster and more efficient transfer than the traditional STIRAP scheme.

Moorad Alexanian, Subir K. Bose

M. Pinard, G. Grynberg, Paul Mandel

Vladimir S. Malinovsky, Svetlana Malinovskaya, Bo Y. Chang +2 more

We demonstrate an efficient population transfer in multi-level quantum systems without partial overlap of pump and Stokes sub-pulses of the weak pulse trains. The transfer mechanism and the robustness of the proposed scheme is discussed.

Youyuan Zhang, Erik Lötstedt, Kaoru Yamanouchi

Abstract The population transfer dynamics in a strongly driven two-level system is studied. It is shown that population inversion can be efficiently achieved when a laser pulse whose photon energy is about half of the energy separation of the two levels is turned on suddenly. This situation is realized when a neutral atom or molecule is ionized at the peak of the laser field, followed by the laser-driven population transfer among two states of an atomic or molecular ion. The mechanism of the efficient population transfer for an ion effectively exposed to a laser field with a sudden turn-on is examined by numerical calculations based on the quasi-stationary Floquet theory.