Quantum Direct Communication using Quantum Walks

S. Srikara, C. M. Chandrashekar

Yanyan Feng, Sisi Liu, Jian Zhou +3 more

Subham Das, Ashtakala Meghanath, Rajiuddin Sk +1 more

Si-si Liu, Yanyan Feng, Jie Li +3 more

Quantum secure direct communication (QSDC) enables direct private message transmission over quantum channels without pre-shared keys. This paper proposes a QSDC protocol based on two-step line-based quantum walks (QWs), which involves sender Alice, receiver Bob and an untrusted third party Charlie, and three stages consisting of preparing, checking quantum channel and communicating secret messages. In the first stage, Bob generates entangled states as the desired quantum channel via one-step QW and prepares decoy photons for the subsequent security checking of the quantum channel; In the second stage, Bob first sends a sequence comprising the photons from the entangled states and Bob’s decoy photons to Alice, who forwards Bob’s decoy photons along with her own decoy photons to Charlie for measurement, with Alice and Bob verifying security by comparing the measurement outcomes; In the third stage, Alice prepares a sequence of photons as coin state for encoding messages to be communicated, which along with the prepared entangled states form a quantum teleportation system, which completes the transmission of the messages under the dominance of another-step QW. Security analyses show the suggested protocol can resist against intercept-and-resend and measure-and-resend attacks, promoting the QSDC’s practicality via QW-based entanglement generation, simplified measurement operations and security checking under the assistance of the third party Charlie.

Prateek Chawla, Adithi Ajith, C. M. Chandrashekar

Abstract The utilization of quantum entanglement as a cryptographic resource has superseded conventional approaches to secure communication. Security and fidelity of intranetwork communication between quantum devices is the backbone of a quantum network. This work presents an protocol that generates entanglement between any two directly connected nodes of a quantum network to be used as a resource to enable quantum communication across that pair in the network. The protocol is based on a directed discrete-time quantum walk and paves the way for private inter-node quantum communication channels in the network. We also present the simulation results of this protocol on random networks generated from various models. We show that after implementation, the probability of the walker being at all nodes other than the source and target is negligible and this holds independent of the random graph generation model. This constitutes a viable method for the practical realisation of secure communication over any random network topology.

Yu‐Guang Yang, Jiajie Yang, Yi‐Hua Zhou +4 more