Efficient protocols for deterministic secure quantum communication using GHZ-like states

TL;DR

This paper introduces two efficient protocols for deterministic secure quantum communication using GHZ-like states, demonstrating their security, high efficiency, and the broader applicability of dense coding in designing such protocols.

Contribution

The paper proposes new DSQC and QSDC protocols using GHZ-like states, showing their efficiency, security, and that dense coding is not essential for these protocols.

Findings

Proposed protocols are highly efficient and secure.

Dense coding is sufficient but not necessary for these protocols.

Maximally efficient QSDC protocols outperform DSQC counterparts.

Abstract

Two protocols for deterministic secure quantum communication (DSQC) using GHZ-like states have been proposed. It is shown that one of these protocols can be modified to an equivalent but more efficient protocol of quantum secure direct communication (QSDC). Security and efficiency of the proposed protocols are analyzed in detail and are critically compared with the existing protocols. It is shown that the proposed protocols are highly efficient. It is also shown that all the physical systems where dense coding is possible can be used to design maximally efficient protocol of DSQC and QSDC. Further, it is shown that dense coding is sufficient but not essential for DSQC and QSDC protocols of the present kind. We have shown that there exist a large class of quantum state which can be used to design maximally efficient DSQC and QSDC protocols of the present kind. It is further, observed that maximally efficient QSDC protocols are more efficient than their DSQC counterparts. This additional efficiency arises at the cost of message transmission rate.