Distributed six-qubit Decoherence Free State Quantum Secure Direct Communication Protocol with Classical Bob

DOI

https://www.doi.org/10.59256/indjcst.20260502101

Published In

Volume 5, Issue 2 (2026)

Published Online

May-August 2026

Pages

928-937

Article Type

Original Article

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A distributed Decoherence Free Space (DFS) state structure based semi-quantum secure direct communication protocol is proposed here. Immunity of DFS states to collective dephasing as well as collective rotation is used to secure the quantum channel. We have used joint bell state measurement of DFS state to detect Eve. The six-qubit DFS state, composed of three singlet states, is used to encode three bits of information in communication. Distributed structure and bell state measurement along with logical invariance of DFS states is explored here for security against various attacks including Trojan Horse attack, Intercept and resend attack, Non unitary attacks Collective attack and establishes no information leakage even in the semi quantum settings.