Quantum Information2 Qubits2x Classical Channel Capacity via Entanglement6 Learning Stages
Superdense Coding
Transmit two classical bits of data by physically sending only a single qubit through an entangled channel.
Stage 6 Required
Plain-Language Intuition
In standard classical communication, if you send 1 physical signal pulse, you can at most send 1 bit of information (either a 0 or a 1).
What if Alice and Bob already share an entangled pair of quantum particles?
In Superdense Coding, Alice can manipulate her single half of the pair using quantum gates (Identity, Bit flip X, Phase flip Z, or both) and send just HER ONE particle to Bob.
When Bob receives that single qubit, he combines it with his particle to read out 2 full classical bits (00, 01, 10, or 11)!
Entanglement effectively doubles the information capacity of a quantum channel!