This kata covers superdense coding - a protocol which allows to transmit two bits of classical information by sending just one qubit using previously shared quantum entanglement. This protocol can be thought of as the dual to the teleportation protocol, which allows to transfer the state of a qubit by sending two classical bits.
- A good description can be found in the Wikipedia article.
- A great interactive demonstration can be found on the Wolfram Demonstrations Project.
- Superdense coding protocol is described in Nielsen & Chuang, section 2.3 (pp. 97-98).