Can Quantum discord increase in a quantum communication task?

TL;DR

This paper investigates whether quantum discord can increase during a quantum teleportation process, revealing scenarios where the receiver's discord surpasses the sender's and analyzing the implications for teleportation fidelity.

Contribution

It demonstrates that quantum discord can be increased through a specific teleportation protocol and explores the inverse relationship between sender's and receiver's discord.

Findings

Quantum discord can be higher in the receiver's state after teleportation.

An increase in the sender's discord correlates with a decrease in the receiver's discord.

Teleportation fidelity improves when using the receiver's prepared state as the channel.

Abstract

Quantum teleportation of an unknown quantum state is one of the few communication tasks which has no classical counterpart. Usually the aim of teleportation is to send an unknown quantum state to a receiver. But is it possible in some way that the receiver's state has more quantum discord than the sender's state? We look at a scenario where Alice and Bob share a pure quantum state and Alice has an unknown quantum state. She performs joint measurement on her qubits and channel to prepare Bob's qubits in a mixed state which has higher quantum discord than hers. We also observe an interesting feature in this scenario, when the quantum discord of Alice's qubits increases, then the quantum discord of Bob's prepared qubits decreases. Furthermore, we show that the fidelity of one-qubit quantum teleportation using Bob's prepared qubits as the channel is higher than using Alice's qubits.