Superdense coding: Difference between revisions

Revision as of 05:59, 2 June 2011

Revision as of 06:00, 2 June 2011

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== Overview ==

Suppose Alice would like to send classical information to Bob using [[qubit]]s, instead of classical [[bit]]s. Alice would encode the classical information in a qubit and send it to Bob. After receiving the qubit, Bob recovers the classical information via [[Measurement in quantum mechanics|measurement]]. The question is: how much classical information can be transmitted per qubit? Since non-orthogonal [[quantum state]]s cannot be distinguished reliably, one would guess that Alice can do no better than one classical bit per qubit. Indeed [[NayakHolevo's boundtheorem|this bound]] on efficiency has been proven formally. Thus there is no advantage gained in using qubits instead of classical bits. However, with the additional assumption that Alice and Bob share an [[entangled state]], two classical bits per qubit can be achieved. The term ''superdense'' refers to this doubling of efficiency.

== Details ==