An atom–waveguide system, which presents one of the quantum interfaces that enable strong couplings between light and atoms, can support tightly-confined guided modes of light. In this distinctive quantum interface, we theoretically investigate the crossover from a delocalized to localized atomic excitation under long-range dipole–dipole interactions and lattice disorders. Both localization lengths of the excitation distributions and power-law scalings of dissipative von Neumann entanglement entropy show signatures of this crossover. We further calculate numerically the level statistics of the underlying non-Hermitian Hamiltonian, from which as the disorder strength increases, the gap ratio decreases and the intrasample variance increases before reaching respective saturated values. The mean gap ratio in the deeply localized regime is close to the one from Poisson statistics along with a relatively large intrasample variance, whereas in the nondisordered regime, a significant level repulsion emerges. Our results provide insights to study the non-ergodic phenomenon in an atom–waveguide interface, which can be potentially applied to photon storage in this interface under dissipations.

原子-波导系统提供了一种量子界面，可以实现光和原子之间的强耦合，可以支持严格限制的光导模式。在这个独特的量子界面中，我们从理论上研究了在长程偶极-偶极相互作用和晶格紊乱下从离域原子激发到局部原子激发的交叉。激发分布的定位长度和耗散冯诺依曼纠缠熵的幂律标度都显示了这种交叉的特征。我们进一步以数值方式计算潜在非厄米哈密顿量的水平统计量，从中随着无序强度的增加，间隙比减小，样本内方差在达到各自的饱和值之前增加。深度局部区域中的平均间隙比接近泊松统计中的值，并且样本内方差相对较大，而在非无序状态中，出现了显着的排斥水平。我们的结果为研究原子 - 波导界面中的非遍历现象提供了见解，这可以潜在地应用于该界面中耗散下的光子存储。