Quantum cryptographic protocols with dual messaging system via 2D alternate quantum walk of a genuine single-photon entangled state

TL;DR

This paper presents a novel quantum cryptographic protocol utilizing 2D alternate quantum walks to generate single-photon entangled states capable of securely encoding two messages simultaneously, with proven security and experimental feasibility.

Contribution

It introduces a new cryptographic scheme based on 2D quantum walks producing multi-way entangled single-photon states for secure dual-message encoding.

Findings

Protocols are resilient against intercept-and-resend attacks.

Experimental realization using photon degrees of freedom is feasible.

Protocols offer unconditional security for quantum communication.

Abstract

A single-photon entangled state (or single-particle entangled state (SPES) in general) can offer a more secure way of encoding and processing quantum information than their multi-photon (or multi-particle) counterparts. The SPES generated via a 2D alternate quantum-walk setup from initially separable states can be either 3-way or 2-way entangled. This letter shows that the generated genuine three-way and nonlocal two-way SPES can be used as cryptographic keys to securely encode two distinct messages simultaneously. We detail the message encryption-decryption steps and show the resilience of the 3-way and 2-way SPES-based cryptographic protocols against eavesdropper attacks like intercept-and-resend and man-in-the-middle. We also detail the experimental realization of these protocols using a single photon, with the three degrees of freedom being OAM, path, and polarization. We have proved that the protocols have unconditional security for quantum communication tasks. The ability to simultaneously encode two distinct messages using the generated SPES showcases the versatility and efficiency of the proposed cryptographic protocol. This capability could significantly improve the throughput of quantum communication systems.