Superdense coding
= Superdense coding
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= Quantum dense coding
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<Superdense coding> uses a shared <Bell state> to communicate two classical <bits> by transmitting one <qubit>. The sender selects one of four orthogonal <Bell states> with a local <Pauli operator>, and the receiver performs a <Bell-basis measurement>. For an ideal shared <Bell pair>, the transmitted <qubit> alone has a <maximally mixed state> for every message and reveals no information about the chosen encoding.