Abstract:
The unique features of quantum walk, such as the possibility of the walker to be in superposition of the position space and get entangled with the position space, provide inherent advantages that can be captured to design highly secure quantum communication protocols. Here we propose two quantum direct communication protocols, a quantum secure direct communication protocol and a controlled quantum dialogue (CQD) protocol using discrete-time quantum walk on a cycle. The proposed protocols are unconditionally secure against various attacks such as the intercept-resend attack, the denial of service attack, and the man-in-the-middle attack. Additionally, the proposed CQD protocol is shown to be unconditionally secure against an untrusted service provider and both the protocols are shown more secure against the intercept resend attack as compared to the qubit-based LM05/DL04 protocol.