Abstract: The quantum entangled degrees of entangled states decreased  with the transmission distance increasing or external interference. The entangled degree was reduced or no longer entangled under the decoherence effect of interaction between light and environment. We designed a set of  one\|dimensional photonic crystals when the entangled light  of two-photon or three-photon passed through photonic crystal, and the superimposed parameter was 003—098, the entangled degree E was 0.8—1, so that the quantum  entangled  state could be transported for a  long distance to achieve quantum communication better.

Key words: quantum entanglement, quantum communication, entanglement amplifier, photonic crystal