The propagation of light in strongly coupled atomic media takes place through the formation of polaritons—hybrid quasiparticles resulting from a superposition of an atomic and a photonic excitation. Here we consider the propagation under the condition of electromagnetically induced transparency and show that a novel many-body phenomenon can appear due to strong, dissipative interactions between the polaritons. Upon increasing the photon-pump strength, we find a first-order transition between an opaque phase with strongly broadened polaritons and a transparent phase where a long-lived polariton branch with highly tunable occupation emerges. Across this nonequilibrium phase transition, the transparency window is reconstructed via nonlinear interference effects induced by the dissipative polariton interactions. Our predictions are based on a systematic diagrammatic expansion of the nonequilibrium Dyson equations which can be controlled, even in the nonperturbative regime of large single-atom cooperativities, provided the polariton interactions are sufficiently long-ranged. Such a regime can be reached in photonic crystal waveguides thanks to the tunability of interactions, allowing us to observe the interaction-induced transparency transition even at low polariton densities.

中文翻译：

---

相互作用引起的强耦合极化子的透明度

光在强耦合原子介质中的传播通过极化子的形成而发生，极化子是原子的叠加和光子激发所产生的混合准粒子。在这里，我们考虑电磁感应透明条件下的传播，并表明由于极化子之间的强耗散相互作用，会出现一种新颖的多体现象。随着光子泵浦强度的增加，我们发现极化子之间的不透明相与极化相之间的一阶跃迁与占据高度可调态的极化子长寿命分支出现了。跨此非平衡相变，通过耗散极化子相互作用引起的非线性干扰效应来重建透明窗口。我们的预测基于非平衡Dyson方程的系统图解扩展，即使极化子相互作用足够长程，即使在大单原子协作性的非微扰状态下，也可以控制非平衡Dyson方程。由于相互作用的可调谐性，在光子晶体波导中可以达到这样的状态，即使在低极化子密度下，我们也可以观察到相互作用引起的透明跃迁。