Why photons are free from decoherence?

[gioialorusso]

Hi everybody,
which are the physical laws that make photons free from decoherence? I only read about the fact that photons have no charge, but why this implies no decoherence?
Thanks you all,
gioia

 

[Mr_Physicist]

Photons are mostly free of decoherence because they do not interact with each other directly and we have many materials in which photons interact minimally with their environment, like glass. This is in contrast to most other particles, such as electrons. In a vacuum far away from any other influences, an electron would also be free of decoherence. However, in the real world, electrons interact very strongly with their environment (because of their charge), leading them to lose, for instance, whatever information they were carrying. This is a very simple answer regarding a very complicated subject, but I hope this answers your question.

 

[gioialorusso]

you have been very clear and your explanation is reasonable, thank you. are there physics motivation to this behave? like, i don't know, their quantized energy, their bosonic properties..? I read also that photons interact very little with each other directly, so is very difficult to realize logic gates with two qubit, is it right? and for make them interact, are there some solution? (like using an atom to make them interact via this atom?)
thank you very very much.