Entanglement-assisted quantum communication with simple measurements

TL;DR

This paper demonstrates that simple, partial Bell state measurements can enable strong entanglement-assisted quantum communication, revealing scenarios where entanglement's power is accessible with scalable, straightforward optical experiments.

Contribution

It shows that entanglement-assisted communication can be achieved with simpler measurements than previously thought, including partial Bell state analysis and product measurements.

Findings

Partial Bell state analysers enable non-classical correlations.

Product measurements suffice for optimal quantum predictions with entanglement.

Simple optical setups can harness entanglement for enhanced communication.

Abstract

Dense coding is the seminal example of how entanglement can boost qubit communication, from sending one bit to sending two bits. This is made possible by projecting separate particles onto a maximally entangled basis. We investigate more general communication tasks, in both theory and experiment, and show that simpler measurements enable strong and sometimes even optimal entanglement-assisted qubit communication protocols. Using only partial Bell state analysers for two qubits, we demonstrate quantum correlations that cannot be simulated with two bits of classical communication. Then, we show that there exists an established and operationally meaningful task for which product measurements are sufficient for the strongest possible quantum predictions based on a maximally entangled two-qubit state. Our results reveal that there are scenarios in which the power of entanglement in enhancing quantum communication can be harvested in simple and scalable optical experiments.