The combination of Rydberg atoms and electromagnetically induced transparency (EIT) has been extensively studied in the strong-interaction regime. Here we proposed utilizing an EIT medium with a high optical depth (OD) and a Rydberg state of low principal quantum number to create a many-body system of Rydberg polaritons in the weak-interaction regime. The phase shift and attenuation induced by the dipole–dipole interaction (DDI) were still significant, and can be viewed as the consequences of elastic and inelastic collisions among Rydberg polaritons. We further observed that the width of the transverse momentum distribution of Rydberg polaritons at the exit of the system became notably smaller as compared with that at the entrance. The observation demonstrates the cooling effect in this system. The μs-long interaction time due to the high-OD EIT medium plus the μm²-size collision cross section due to the DDI suggests a feasible platform of polariton Bose–Einstein condensation.

Rydberg原子与电磁感应透明性（EIT）的结合已在强相互作用机制中得到了广泛的研究。在这里，我们建议利用具有高光学深度（OD）和低主量子数的Rydberg态的EIT介质在弱相互作用体系中创建Rydberg极化子的多体系统。偶极-偶极相互作用（DDI）引起的相移和衰减仍然很显着，可以看作是里德堡极化子之间发生弹性和非弹性碰撞的结果。我们进一步观察到，系统入口处的Rydberg极化子的横向动量分布宽度与入口处相比明显变小。观察结果证明了该系统的冷却效果。DDI引起的^2级碰撞横截面表明极化子Bose-Einstein凝聚的可行平台。