Multiplexed Entanglement using Optically Addressable Solid-state Qubits

Multi-emitter nodes are crucial for enhancing quantum communication bandwidth in practical quantum networks. Solid-state platforms offer a promising solution by hosting numerous frequency-resolved qubits within the mode volume of a single cavity, providing a natural platform for multiplexing. However, robustly and efficiently entangling distinguishable qubits remains a key challenge.

In this work, we demonstrate multiplexed entanglement distribution in a two-node network, where each node comprises multiple single ¹⁷¹Yb ions situated in nanophotonic crystal cavities [1]. We entangle pairs of distinguishable ions with a novel protocol based on frequency-erasing photon detection and real-time feedforward using photon detection times. Furthermore, this protocol is robust to optical frequency fluctuations: a universal challenge for solid-state emitters [1,2].

In addition, by identifying and entangling two remote ¹⁷¹Yb ion pairs, we boost the inter-node entanglement rate by a factor of two through parallelizing the initialization of ions within the same device. During the entanglement protocol, we observe negligible crosstalk between co-located ions and minimal degradation in entanglement fidelity.

Our results highlight the scalability of solid-state platforms and pave the way for employing rare-earth ions in crystals for quantum networking applications.



[1] Ruskuc*, Wu* et al. arXiv:2402.16224

[2] Uysal, Thompson, arXiv:2406.06497