Feasibility of satellite-augmented global quantum repeater networks

Abstract

A large scale quantum network requires the distribution of high-fidelity end-to-end entanglement. To overcome the range limitations inherent to terrestrial fiber, a leading architecture has emerged: satellite-based sources transmitting entanglement to quantum repeaters on the ground. By bridging the gap between abstract analytical frameworks and computationally heavy numerical simulations, this paper provides the first quantitative answer to the question of such a network's achievable performance with current and near-term space technology, while accounting for entanglement swapping and purification. This is achieved by integrating a detailed physical model of a satellite-to-ground link into an analytical entanglement resource estimation framework for quantum repeaters, enabling an optimization of the end-to-end entanglement rate. Our analysis, performed across leading quantum hardware platforms, shows that Low Earth Orbit satellite constellations combined with quantum repeaters employing Neutral Atom or Nitrogen and Silicon Vacancy qubits, could enable a global quantum network, distributing entanglement over distances up to 20,000 km, sufficient for connecting any two points on Earth. This work highlights the major bottlenecks in space and quantum hardware technologies, which need to be addressed, thereby guiding informed investments necessary for enabling a large scale quantum network.

Figures (9)

• Figure 1: Satellite-assisted nested repeater protocol. SPDC sources mounted on LEO satellites send entangled photons to the optical ground stations (OGS). Once the entanglement is stored in the quantum memories at the OGS, the nested repeater protocol (Appendix \ref{['app:Theoretical Framework for Repeater-Assisted Networks']}) is employed to establish a direct entanglement link between the end nodes.
• Figure 2: End-to-end rates using state of the art space technology (Scenario A): plotted across three quantum repeater platforms -- NV and SiV centers and Atoms -- and different satellite altitudes: from 500 to 2,000 km.
• Figure 3: (a) The inter-station distance $L_0$ that maximizes the end-to-end rate $R$. The area under the line $L=L_0$, where repeaters are useful, has been shaded (b) maximum achievable end-to-end rate $R$, accounting for all satellite altitudes plotted against the distance between the end nodes for Neutral Atoms, Silicon Vacancy (SiV), and Nitrogen Vacancy (NV) platforms.
• Figure 4: End-to-end rates using near-future space technology (Scenario B): plotted across three quantum repeater platforms -- NV and SiV centers and Atoms -- and different satellite altitudes: from 500 to 2,000 km.
• Figure 5: (a) The inter-station distance $L_0$ that maximizes the end-to-end rate $R$. The area under the line $L=L_0$, where repeaters are useful, has been shaded (b) maximum achievable end-to-end rate $R$, accounting for all satellite altitudes plotted against the distance between the end nodes for Neutral Atoms, Silicon Vacancy (SiV), and Nitrogen Vacancy (NV) platforms.