Strategies for entanglement distribution in optical fiber networks

TL;DR

This paper compares entanglement distribution protocols in noisy optical fiber networks, demonstrating that using a separable carrier photon can achieve higher distribution rates than traditional methods under certain conditions.

Contribution

It introduces and analyzes protocols using a separable carrier photon with optical CNOT gates, showing their potential for improved entanglement distribution in realistic noisy environments.

Findings

Separable carrier protocols can outperform standard methods in entanglement rate.

Higher success probability of CNOT gates enhances protocol performance.

Depolarizing noise impacts entanglement distribution efficiency.

Abstract

Distributing entanglement over long distances remains a challenge due to its fragility when exposed to environmental effects. In this work, we compare various entanglement distribution protocols in a realistic noisy fiber network. We focus specifically on two schemes that only require the sending of a non-entangled carrier photon to remote nodes of the network. These protocols rely on optical CNOT gates and we vary the probability with which they can be successfully performed. Encoding our entangled states in photon polarization, we analyse the effect of depolarizing noise on the photonic states as the carrier passes through the fibers. Building a robust model of photon loss and calculating the distillable entanglement of the noisy states, we find the entanglement distribution rate. We discover that methods involving a separable carrier can reach a higher rate than the standard entanglement distribution protocol, provided that the success probability of the optical CNOT gates is sufficiently high.