On Selecting Paths for End-to-End Entanglement Creation in Quantum Networks

TL;DR

This paper explores how prior entanglements and entanglement diversity can be leveraged to optimize path selection for faster and more reliable end-to-end entanglement creation in quantum networks, considering quantum-specific constraints.

Contribution

It introduces the concept of using prior entanglements in path selection and proposes strategies involving entanglement diversity to improve quantum network performance.

Findings

Longer paths with prior entanglements can outperform shorter paths in certain scenarios.

Using multiple paths can improve fidelity through entanglement distillation.

Prior entanglements significantly impact optimal routing decisions in quantum networks.

Abstract

Optimal routing is a fundamental challenge in quantum networking, with several approaches proposed to identify the most efficient path for end-to-end (e2e) entanglement generation between pairs of nodes. In this paper, we show that \textit{prior entanglements} -- entanglements generated in a previous network cycle but not yet utilized -- are an important consideration in optimal path selection due to the dynamic nature of quantum networks. Specifically, we investigate whether a longer path with pre-existing entanglements can outperform a shorter path that starts from scratch. We account for key quantum constraints, including noisy entanglement generation and swapping, fidelity decay, probabilistic operations, and link discarding upon swap failure. Simulations reveal that longer paths with prior entanglements can establish e2e entanglement faster than shorter paths under certain conditions. We further introduce the notion of \textit{entanglement diversity}, where multiple paths can be used to improve performance -- either by selecting the first successful path to minimize time or using both paths to enhance fidelity through distillation. These findings highlight the importance of incorporating prior entanglements into path selection strategies for optimizing quantum communication networks.