Quantum communication with macroscopically bright nonclassical states

TL;DR

This paper investigates the use of bright multimode nonclassical light states for quantum communication, highlighting the importance of mode-matching in homodyne detection to enable secure quantum key distribution with bright beams.

Contribution

It demonstrates the feasibility of multimode quantum key distribution using bright beams and analyzes the impact of mode-matching on detection sensitivity and entanglement measurement.

Findings

Homodyne detection sensitivity depends on mode-matching quality.

Unmatched modes introduce noise limiting entanglement detection.

Quantum key distribution with bright beams is feasible with proper mode-matching.

Abstract

We analyze homodyne detection of macroscopically bright multimode nonclassical states of light and propose their application in quantum communication. We observe that the homodyne detection is sensitive to a mode-matching of the bright light to the highly intense local oscillator. Unmatched bright modes of light result in additional noise which technically limits detection of Gaussian entanglement at macroscopic level. When the mode-matching is sufficient, we show that multimode quantum key distribution with bright beams is feasible. It finally merges the quantum communication with classical optical technology of visible beams of light.