# Information carried by single photon

In Quantum Information we can use photons for quantum bits (qubits). What i often read is that each photon can carry one unit of information, i.e. using the polarization state of a single photon.
I have two questions:
1) i read on this article that it is possible to send 1.63 bits of information per photon, what does that mean?
http://www.newscientist.com/article/dn13522-twisting-light-packs-more-information-into-one-photon.html#.Uy1cKBx22QE
2)If i can take a single photon state as a tensor product of its polarization state and its orbital angular momentum state (we could also add a frequency state), can i say that i am sending 2 (or 3) qubits of information in one single photon?
Thank you

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As always, Alice wants to send bits to Bob. Before they start, however, they already establish a connection by sharing a maximally entangled state $|\Phi\rangle=\frac{|00\rangle+|11\rangle}{\sqrt{2}}$. So, in principle, they take a two-photon state and each of them has one photon. Alice can now act on her photon and produce (via local transformation) any of the four Bell states that are available. She can then send her photon to Bob and Bob can measure the two-photon state, obtaining one of the four Bell states (depending of what Alice did). So during the protocol, Alice sent ONE photon but Bob obtains TWO bits of information (four possible outcomes). So it seems that you can actually send two bits of information with one photon.