AI 中文总结
研究提出脉冲整形方法优化多态STIRAP，扩展准平行本征能量方法到多态链，推导脉冲形状公式并应用于特定态链。数值模拟显示优化脉冲降低布居转移误差，提高鲁棒性，且在有损情况也有优势，还比较了不同角动量链的情况。
AI 中文摘要
我们提出一种脉冲整形方法，用于改善仅具有近邻耦合的多态受激拉曼绝热通道（STIRAP）中的布居转移。该方法将先前用于二态和三态系统的准平行本征能量方法扩展到多态链，且不引入额外的捷径场。对泵浦场和斯托克斯场进行整形，使最接近暗态的本征能量在相互作用的中心部分与暗态保持近乎平行，此部分非绝热跃迁最易发生。我们推导了所需脉冲形状的解析公式，并将其应用于由角动量为\(J_g\rightarrow J_e = J_g\)和\(J_g\rightarrow J_e = J_g - 1\)的简并流形的磁子能级形成的五态、七态和九态链。数值模拟表明，与标准高斯脉冲相比，优化后的脉冲可将布居转移误差降低几个数量级。相同形状还提高了对拉比频率峰值、单光子失谐和多光子失谐变化的鲁棒性。两个角动量族的比较表明，\(J_g\rightarrow J_g\)链通常更有利，因为其克莱布施 - 戈尔登系数在暗态变化最迅速的区域使相关亮态间隙更大。最后，自发辐射模拟表明，优化后的共振脉冲在有损情况下也具有优势。
英文摘要
We propose a pulse-shaping method for improving population transfer in multistate stimulated Raman adiabatic passage (STIRAP) with nearest-neighbour couplings only. The method extends the quasiparallel-eigenenergy approach, previously used for two- and three-state systems, to multistate chains without introducing additional shortcut fields. The pump and Stokes fields are shaped so that the eigenenergies closest to the dark state remain nearly parallel to it during the central part of the interaction, where nonadiabatic transitions are most likely to occur. We derive analytic prescriptions for the required pulse shapes and apply them to five-, seven-, and nine-state chains formed by magnetic sublevels of degenerate manifolds with angular momenta $J_g\rightarrow J_e=J_g$ and $J_g\rightarrow J_e=J_g-1$ driven by a pair of right- and left-circularly polarized pulses. Numerical simulations show that the optimized pulses can reduce the population transfer error by several orders of magnitude compared to standard Gaussian pulses. The same shapes also improve robustness against variations of the peak Rabi frequency, the single-photon detuning, and the multiphoton detuning. The comparison between the two angular-momentum families shows that the $J_g\rightarrow J_g$ chains are generally more favourable, because their Clebsch-Gordan coefficients keep the relevant bright-state gap larger in the region where the dark state changes most rapidly. Finally, simulations with spontaneous emission show that the optimized resonant pulses remain advantageous in the lossy regime as well.
