Maximally efficient protocols for direct secure quantum communication

Siddharth Patwardhan, Subhayan Roy Moulick, Prasanta K. Panigrahi

Georgi Bebrov, Rozalina Dimova

Xiaoxue Zhang, Ri‐Gui Zhou

Anindita Banerjee, Anirban Pathak

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.

Vandana Vanegal

Two effective stable quantum communication protocols using 3-qubit and 4-qubit symmetric W states have recently been suggested. These two protocols based on dense coding are extended and their efficiencies are greatly increased. Simplebounds are obtained on the qubit efficiency of determinist safe quantum communication (DSQC) and quantum secure direct communication (QSDC) protocols, and it is shown that dense coding is not sufficient for the design of DSQC and QSDC protocols that are maximally effective. This fact is used to develop DSQC and QSDC protocols that are maximally effective using 3-qubit and 4-qubit W states.

Jian Li, Zhengyan Zhou, Na Wang +3 more

A quantum secure direct communication (QSDC) protocol based on the hyper-entangled state is proposed to improve the efficiency of eavesdropping detection in an improved “ping-pong” protocol, in which we use the hyper-entangled state to detect eavesdropping during the quantum communication. In the security analysis, we use the entropy theory method to calculate the amount of information and compare the detection strategy of two QSDC protocols quantitatively by comparing the constraint between the maximal amount of information that the eavesdropper can get, and the probability that the eavesdropper is detected. The probability of being detected will be 50% in the original QSDC protocol which based on the Bell states if the eavesdropper attempts to get all the information, however, in the proposed protocol this probability can reach 75%, which indicates that the proposed protocol is more secure.