Progress Toward Heralded Remote Entanglement of Single Rb and Cs Atoms via Telecom-band Frequency Conversion

Entanglement between remote, stationary quantum memories is a key resource for quantum networks and modular quantum computing. Furthermore, a dual-species neutral-atom platform further enables heterogeneous architectures for efficient quantum error correction. In this work, we present an experimental protocol and current progress toward heralded entanglement between distant single-atom nodes based on Rb and Cs using telecom-band quantum frequency conversion. At each node, we generate atom-photon entanglement and encode the photonic qubit in polarization on the Rb D2 (780 nm) and Cs D2 (852 nm) transitions. The photons are routed to the middle, where a two-photon Bell-state measurement projects the distant atoms into an entangled state. The 852 nm Cs photon is converted into a 1513 nm (telecom band) photon with a PPLN-based frequency conversion module for low-loss fiber transmission, and then reconverted to 780 nm in a second PPLN-frequency conversion stage. This quantum frequency-conversion-enabled link provides a practical route to entangle disparate neutral-atom qubits and extends near-IR quantum nodes to telecom fiber, supporting scalable long-distance networking.