Coherent states

As a Coherent Radiation (English: coherent radiation ) is called in the natural sciences electromagnetic waves that have a fixed phase relationship with respect to their spatial and temporal spread. This concept can also be applied to particle flows, such as on an electron, since the particles also have a wave nature. But it can not be applied to individual particles, as they are represented by the wave packets. Laser and maser, or synchrotrons produce coherent radiation. In practice, an electromagnetic wave is, however, only over a limited distance coherent ( coherence length). For the quantum mechanical description, see Coherent state.