Experimental demonstrations of unconditional security in a purely classical regime
This provides a classical alternative to quantum key distribution for secure communication, potentially broadening access to unconditional security.
The paper tackles the problem of achieving unconditional security in key distribution without quantum mechanics by experimentally demonstrating the Unconditionally Secured Classical Key Distribution (USCKD) protocol, which uses classical channels and orthogonal bases with deterministic randomness in a coupled Mach-Zehnder interferometer.
So far, unconditional security in key distribution processes has been confined to quantum key distribution (QKD) protocols based on the no-cloning theorem of nonorthogonal bases. Recently, a completely different approach, the unconditionally secured classical key distribution (USCKD), has been proposed for unconditional security in the purely classical regime. Unlike QKD, both classical channels and orthogonal bases are key ingredients in USCKD, where unconditional security is provided by deterministic randomness via path superposition-based reversible unitary transformations in a coupled Mach-Zehnder interferometer. Here, the first experimental demonstration of the USCKD protocol is presented.