Information carrued by photons.

The information a photon carries is just like the information an email or telegram carries.

There are many different possible quantum states a photon or group of photons can be in.

If we assign a letter, number or other symbol to each possible quantum state, we can send that photon in some quantum state from A to B, where it can be received, and read.

The better we care able to distinguish between different states of a photon, the better we are able to write and read information encoded in photon states.