We investigate the behaviors of quantum coherence (QC) for an atom coupled to the fluctuating electromagnetic field under the cosmic string spacetime. It is found that vacuum fluctuation, atomic polarization and nontrivial spacetime topology affect the QC behaviors. When deficit angle parameter \(\nu =1\) and atom is far away from the string, the results restore to that of free Minkowski spacetime. When atom lies in the string and is transversely polarizable, the atom seems like a closed system, and QC completely is not affected by the electromagnetic fluctuation. For nonzero atom–string distance, QC presents oscillatory behaviors as atom–string distance changes, and larger deficit angle parameter causes more prominent oscillation. In a sense, the string can protect the QC to some extent, which is similar to the boundary effect in Minkowski spacetime. Besides, this atom eventually evolves to an incoherent state, which does not appear to be related to the initial state and other various parameters; this means QC cannot keep for long evolution time in the cosmic string spacetime. In principle, atomic polarization, atom–string distance and deficit angle parameter provide us more freedom to steer the QC behaviors, which might be useful to sense various cosmic string spacetime and distinguish the cosmic string spacetime from Minkowski spacetime.

我们研究在宇宙弦时空下耦合到波动电磁场的原子的量子相干行为。发现真空起伏，原子极化和非平凡的时空拓扑会影响QC行为。当亏角参数\（\ nu = 1 \）并且原子远离字符串，结果恢复为自由的Minkowski时空。当原子位于弦中并且可横向极化时，该原子看起来像是一个封闭的系统，并且QC完全不受电磁波动的影响。对于非零原子串距离，当原子串距离变化时，QC表现出振荡行为，并且更大的赤字角参数会导致更明显的振荡。从某种意义上说，字符串可以在一定程度上保护QC，这类似于Minkowski时空中的边界效应。此外，该原子最终演化为非相干状态，该状态与初始状态和其他各种参数无关。这意味着QC无法在宇宙弦的时空中保持很长的演化时间。原则上，原子极化