Abstract

This disclosure describes a method and system for securing free-space Quantum Key Distribution (QKD) against intercept-and-resend, quantum cloning, and wide-aperture phase-matching attacks by employing multi-spatial mode quantum states combined with real-time, non-local phase collapse. Rather than encoding cryptographic keys in conventional linear single-photon streams, the system distributes information across the Orbital Angular Momentum (OAM) and radial phase profiles of a macroscopic, spatially sculpted wavefront through a dynamically varying Topological Transposition matrix, M(t). This approach renders the encoded information inherently orthogonal to conventional linear eavesdropping apertures while enabling high-dimensional quantum state encoding.

To protect against partial interception and coherent cloning attempts, the transmitted payload is hyper-entangled with an orthogonal network of high-dimensional Greenberger-Horne-Zeilinger (GHZ) sentinel states. Any unauthorized localized projective measurement, PEve, performed on even a fractional spatial sub-mode initiates a non-local, measurement-induced quantum Zeno dynamic that propagates throughout the entangled wavefront. Rather than relying on conventional QKD protocols that detect eavesdropping through post-transmission error analysis, the disclosed system actively destroys the transmitted quantum information at the physical layer during interception. The resulting avalanche collapse irreversibly converts the remaining unread, forward-propagating wavefront into a maximum-entropy mixed thermal noise state (ρnoise) before it can reach downstream receivers or adversaries, thereby implementing a native quantum "scorched earth" protocol that prevents information recovery following unauthorized measurement.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

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