计算到三阶微扰项，其结果可用于双光子及三光子共振过程。

The first three terms of the perturbation are obtained, which can be used for two or three photon resonant processes.

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但将它的分母作泰勒展开，经过重新整理，将那些大小不一致的项消去后，得到的新微扰展开式是逐项大小一致的。

However, when its denominator was expanded in a Taylor series, a size consistent perturbation expansion was obtained, for the size inconsistent terms turned out to be cancelled out.

youdao

但将它的分母作泰勒展开，经过重新整理，将那些大小不一致的项消去后，得到的新微扰展开式是逐项大小一致的。

However, when its denominator was expanded in a Taylor series, a size consistent perturbation expansion was obtained, for the size inconsistent terms turned out to be cancelled out.

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