Robustness of bipartite Gaussian entangled beams propagating in lossy channels

TL;DR

This paper investigates the fragility of bipartite Gaussian entangled beams in lossy channels, identifying conditions for entanglement sudden death and proposing ways to produce more robust quantum states for secure optical communication.

Contribution

It provides a detailed analysis of entanglement robustness in lossy environments and introduces methods to generate states resistant to decoherence, advancing quantum communication technology.

Findings

Identified conditions leading to entanglement sudden death.

Demonstrated techniques to produce loss-robust entangled states.

Enhanced understanding of quantum entanglement behavior in practical channels.

Abstract

Subtle quantum properties offer exciting new prospects in optical communications. Quantum entanglement enables the secure exchange of cryptographic keys and the distribution of quantum information by teleportation. Entangled bright beams of light attract increasing interest for such tasks, since they enable the employment of well-established classical communications techniques. However, quantum resources are fragile and undergo decoherence by interaction with the environment. The unavoidable losses in the communication channel can lead to a complete destruction of useful quantum properties -- the so-called "entanglement sudden death". We investigate the precise conditions under which this phenomenon takes place for the simplest case of two light beams and demonstrate how to produce states which are robust against losses. Our study sheds new light on the intriguing properties of quantum entanglement and how they may be tamed for future applications.