Heralding Quantum Entanglement between Two Room-Temperature Atomic Ensembles

Establishing quantum entanglement between individual nodes is crucial for building large-scale quantum networks, enabling secure quantum communications, distributed quantum computing, enhanced quantum metrology, and fundamental tests of quantum mechanics. However, the shared entanglements have been merely observed in either extremely low-temperature or well-isolated systems, which limits quantum networks for real-life applications. Here, we report the realization of heralding quantum entanglement between two atomic ensembles at room temperature, which are contained in two spatially separated, centimeter-sized vapor cells. By mapping the atomic state onto a photonic state after the readout process, we measure the quantum interference of the Raman-scattered photons and reconstruct the entangled state, then we strongly verify the existence of a single excitation delocalized in two atomic ensembles. The demonstrated building block paves the way to construct quantum networks and distributing entanglement across multiple remote nodes at ambient conditions.