Can communication power of separable correlations exceed that of entanglement resource?

TL;DR

This paper investigates the remote state preparation protocol, demonstrating that under certain resource limitations, separable states can outperform entangled states in communication efficiency.

Contribution

It proves that separable states cannot surpass entangled states generally, but can do so when the decoding agent has limited information or restricted operations.

Findings

Separable states cannot exceed entangled states in efficiency under ideal conditions.

Limited decoding resources can enable separable states to outperform entangled states.

Resource restrictions like lack of information or bistochastic operations are critical factors.

Abstract

The scenario of remote state preparation with shared correlated quantum state and one bit of forward communication [B. Dakic et al. Nature Physics 8, 666-670 (2012)] is considered. The transmission efficiency is examined by considering general encoding and decoding strategies. The importance of use of linear fidelity is recognized. It is shown that separable states cannot exceed the efficiency of entangled states in this protocol. It is proven however that such a surprising phenomena may naturally occur when the decoding agent has limited resources in the sense that either (i) has no information about the coordinates in the sender plane being in question or (ii) is forced to use bistochastic operations only which may be imposed by physically inconvenient local thermodynamical conditions.