相干性是物理学的一个基本概念。相干性不仅与电磁场（光子系综）状态有关，而且与处于凝聚态的玻色子和费米子集体有关。一个鲜明的例子是超导体中的库珀对系综。此外，在像自感应透明、自感应衰减、光子回波、超辐射等电磁场与物质相互作用的量子光学效应中，相干性也强烈表? Coherence is a basic concept of physics. Coherence is not only related to the state of the electromagnetic field (photon ensemble), but also to the state of the condensed bosons and fermions. A striking example is the Cooper pair ensemble in superconductors. In addition, in the quantum optics such as self-sensing transparent, self-induced attenuation, photon echo, super-radiation and other electromagnetic fields interacting with matter, the coherence is also strong.