Toward Global Quantum Communication: Beam Wandering Preserves Nonclassicality

TL;DR

This paper analyzes how beam wandering in atmospheric channels affects quantum light properties, showing it can preserve nonclassical effects better than standard attenuation, which is crucial for secure long-distance quantum communication.

Contribution

It provides a rigorous, first-principles derivation of the transmissivity distribution under beam wandering and demonstrates its potential to maintain quantum features in atmospheric channels.

Findings

Beam wandering preserves nonclassical effects better than standard attenuation.

The probability distribution of transmissivity due to beam wandering is derived from first principles.

Nonclassical properties like entanglement and squeezing are robust against beam wandering.

Abstract

Tap-proof long-distance quantum communication requires a deep understanding of the strong losses in transmission channels. Here we provide a rigorous treatment of the effects of beam wandering, one of the leading disturbances in atmospheric channels, on the quantum properties of light. From first principles we derive the probability distribution of the beam transmissivity, with the aim to completely characterize the quantum state of light. It turns out that beam wandering may preserve nonclassical effects, such as entanglement, quadrature and photon number squeezing, much better than a standard attenuating channel of the same losses.