We theoretically analyze the collective dynamics of a thermal beam of atomic dipoles that couple to a single mode when traversing an optical cavity. For this setup we derive a semiclassical model and determine the onset of superradiant emission and its stability. We derive analytical expressions for the linewidth of the emitted light and compare them with numerical simulations. In addition, we find and predict two different superradiant phases; a steady-state superradiant phase and a multicomponent superradiant phase. In the latter case we observe sidebands in the frequency spectrum that can be calculated using a stability analysis of the amplitude mode of the collective dipole. We show that both superradiant phases are robust against free-space spontaneous emission and $T_2$ dephasing processes.

中文翻译：

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将热原子束超辐射发射到光腔中

我们从理论上分析了原子偶极子热束穿过光学腔时耦合到单个模式的集体动力学。对于这个设置，我们推导出一个半​​经典模型并确定超辐射发射的开始及其稳定性。我们推导出发射光线宽的解析表达式，并将它们与数值模拟进行比较。此外，我们发现并预测了两种不同的超辐射相；稳态超辐射相和多分量超辐射相。在后一种情况下，我们观察频谱中的边带，可以使用集体偶极子振幅模式的稳定性分析来计算该边带。我们表明，两种超辐射相都对自由空间自发辐射具有鲁棒性，并且${吨}_2$ 去相过程。