"Quantum" key distribution using weak classical light waves

TL;DR

This paper demonstrates that a quantum key distribution protocol similar to E91 can be implemented using weak classical light waves and classical detectors, highlighting the quantum-like properties emerging from classical electromagnetic interactions.

Contribution

It introduces a method for quantum key distribution with weak classical light, challenging the notion that entanglement is strictly necessary for quantum cryptography.

Findings

Weak classical light can be used for quantum-like key distribution

Detection results reflect quantum properties without true quantum states

Protocol mimics properties of E91 quantum cryptography

Abstract

The detection of very weak classical electromagnetic (light) waves by classical macroscopic device is discussed. It is shown that the results of such detection can be interpreted as a manifestation of the quantum properties of radiation, although in reality they are related to the peculiarities of the interaction of weak classical electromagnetic waves with discrete atoms. We show that the "quantum" key distribution protocol can be realized using very weak classical light waves and avalanche detectors, and it possesses all the properties of the quantum cryptographic protocol E91 which based on entangled photons.