Superdense coding: Difference between revisions

Revision as of 07:21, 22 April 2014

Revision as of 03:48, 22 June 2014

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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 [[Holevo's theorem|thisHolevo's boundtheorem]] ondiscusses efficiencythis hasbound beenon proven formallyefficiency. 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.

Also, it can be proved that the maximum amount of classical information that can be sent (even while using entangled state) using one qubit is 2 bits.