Entanglement enhancement of a noisy classical communication channel

TL;DR

This paper analyzes how shared entanglement can improve the success probability of transmitting a bit through a noisy classical channel, focusing on two-qubit systems and extending the protocol for variable channel parameters.

Contribution

It provides a detailed quantum mechanical analysis of an entanglement-assisted communication protocol, establishing optimal measurement strategies and limitations for qubit and qudit systems.

Findings

Maximum enhancement achieved with two-qubit entanglement.

Higher-dimensional entanglement (qudits) does not improve success probability.

Protocol extension for variable channel parameters.

Abstract

We present a formal quantum mechanical analysis of the communication protocol of Prevedel {\it et al.}\ [Phys. Rev. Lett. \textbf{106}, 110505 (2011)], in which entanglement shared by sender and receiver is used to enhance, beyond that achievable via the optimal classical strategy, the probability of successful transmission of a bit through a particular noisy classical channel ${\cal N}$. We provide a full analysis of this protocol when the shared entanglement resides in a two-qubit system. Our analysis shows the measurement choices specified by the protocol yield the maximum possible enhancement of the probability of successful communication of the bit with one use of the channel ${\cal N}$. We determine that shared entanglement residing in a two-qudit system with $d > 2$ cannot provide enhancement beyond that produced by entangled qubits. Finally, we show how the protocol should be extended when probability parameters for the channel ${\cal N}$ are allowed to vary.