我們在常溫下測量銣85電磁誘發透明(EIT)的訊號發現了不尋常的線寬變化，在三能階系統的預測中我們預期看到 EIT 的訊號線寬隨外加耦合光強度增加，為一種線性關係，然而當我們在常溫下用銣85做電磁誘發透明實驗看到的線寬卻隨耦合光強度增加並逐漸趨近飽和。實驗上我們選擇用 Λ 型系統做電磁誘發透明實驗，並猜測有另外一個額外的激發態也參與了交互作用，因此我們在文中建立一個四能階系統擬合這個系統。擬合的結果顯示，相對穿透率與 EIT 峰值中心頻率的偏移皆符合四能階系統預期，只有線寬不符預期，然而在強磁場條件下看到的線寬並無收斂的跡象，推測有額外的效應需要考慮，目前推測這樣的效應可能與拉曼雙光子吸收有關，並嘗試用兩組黎曼系統建模，結果發現線寬隨耦合光強度變化趨緩，但仍呈現性增加的趨勢，推測加入更多黎曼態可以看到預期的收斂效果，之後可以朝這個方向嘗試。

We have observed unusual linewidth behavior in electromagnetically induced transparency experiments with vapor cell of rubidium 85 atoms at room temperature. In the prediction of a three-level system, we expected to see a linear relation between the EIT linewidth and the applied power of the coupling field. However, in our experiment with vapor cells of rubidium 85 atoms at room temperature, we observed that the linewidth increased with the power of the coupling field and gradually approached saturation. Experimentally, we decided to use a Λ-type system for the EIT experiment. We hypothesized that an additional excited state might also be considered. Therefore, we constructed a four-level system model to fit the data. The fitting result showed that the relative transmission rate and the shift of the central frequency of the EIT peak met the expectations of the four-level system, but the linewidth did not. Under a strong magnetic field, the linewidth showed no sign of convergence, suggesting that additional effects may need to be considered. We currently speculate that this effect may be related to the Raman transition. We attempted to model the system using two sets of Zeeman systems and found that the increase of linewidth gradually slowed down with the change in the strength of the coupling field, but the relation between linewidth and the strength of the coupling field still showed a trend of linear increase. We speculate that adding more Zeeman states could achieve the expected convergence effect.

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