Towards Scalable Quantum Networks

TL;DR

The paper investigates scalability limits in quantum communication networks built from trapped-ion routers and Bell State Measurement repeaters. Using the SeQUeNCe simulation framework and a Barrett-Kok entanglement generation protocol, it analyzes how entanglement generation rate and end-to-end fidelity evolve with total distance and node count. Key findings include linear scalability in homogeneous networks, a decrease in entanglement performance with more repeaters at fixed distances in heterogeneous setups, and pronounced even-odd effects in chain topologies, with decoherence dominating at very long distances. The work provides design insights for scalable quantum networks, highlighting routing, memory requirements, and qubit technology choices as critical factors for practical deployment.

Abstract

This paper presents a comprehensive study on the scalability challenges and opportunities in quantum communication networks, with the goal of determining parameters that impact networks most as well as the trends that appear when scaling networks. We design simulations of quantum networks comprised of router nodes made up of trapped-ion qubits, separated by quantum repeaters in the form of Bell State Measurement (BSM) nodes. Such networks hold the promise of securely sharing quantum information and enabling high-power distributed quantum computing. Despite the promises, quantum networks encounter scalability issues due to noise and operational errors. Through a modular approach, our research aims to surmount these challenges, focusing on effects from scaling node counts and separation distances while monitoring low-quality communication arising from decoherence effects. We aim to pinpoint the critical features within networks essential for advancing scalable, large-scale quantum computing systems. Our findings underscore the impact of several network parameters on scalability, highlighting a critical insight into the trade-offs between the number of repeaters and the quality of entanglement generated. This paper lays the groundwork for future explorations into optimized quantum network designs and protocols.

Figures (10)

• Figure 1: Entanglement generation process between two quantum routers, facilitated at the intermediary BSM node. Shows basic network setup and flow of network processes.
• Figure 2: General network setup, showing entanglement between two routers.
• Figure 3: Homogeneous network scalability plot. N is the number of nodes, d distance between nodes, F is end-to-end fidelity and R is the entanglement generation rate.
• Figure 4: Entanglements generated end-to-end across a simulated quantum network of fixed total distance 1000km while varying node count. We observe three individual trends within the scaling.
• Figure 5: Comparison of two separate trends observed within the odd node counts. Within each trend, we still observe the general overall trend yet both vary greatly in a number of entanglements generated.