Dense coding for continuous variables
نویسندگان
چکیده
A scheme to achieve dense quantum coding for the quadrature amplitudes of the electromagnetic field is presented. The protocol utilizes shared entanglement provided by nondegenerate parametric down-conversion in the limit of large gain to attain high efficiency. For a constraint in the mean number of photons n̄ associated with modulation in the signal channel, the channel capacity for dense coding is found to be ln(11n̄1n̄), which always beats coherent-state communication and surpasses squeezed-state communication for n̄.1. For n̄ @1, the dense coding capacity approaches twice that of either scheme.
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