Design Tradeoffs in Photonically Linked Qubit Networks

TL;DR

This paper analyzes photonically linked qubit network protocols, comparing their rate and fidelity performance, and finds that strong-coupling protocols can significantly improve distribution rates while maintaining high fidelity.

Contribution

It introduces and evaluates two strong-coupling protocols for quantum networks, demonstrating their advantages over traditional two-photon interference schemes.

Findings

Strong-coupling protocols can improve distribution rates by 30-75%.

High fidelities of over 99% are maintained with new protocols.

Performance depends on device parameters and photonic degrees of freedom.

Abstract

Quantum networking can be realized by distributing pairs of entangled qubits between remote quantum processing nodes. Devoted communication qubits within each node can naturally interface with photons which bus quantum information between nodes. With the introduction of CQED to enhance interactions between communication qubits and photons, advanced protocols capable of achieving high entanglement distribution rates with high fidelity become feasible. In this paper, we consider two such protocols based on trapped ion communication qubits strongly coupled to small optical cavities. We study the rate and fidelity performance of these protocols as a function of critical device parameters and the photonic degree of freedom used to carry the quantum information. We compare the performance of these protocols with the traditional two-photon interference scheme, subjecting all protocols to the same experimentally relevant constraints. We find that adoption of the strong-coupling protocols could provide substantial distribution rate improvements of $30-75\%$ while maintaining the high-fidelities $\mathcal{F}\gtrsim99\%$ of the traditional scheme.