Entangling Billions of Motional Atoms and an Optical Loop at Ambient Condition

Abstract Quantum entanglement recognized by Einstein, Podolsky, Rosen and Schrodinger is the essence of quantum physics, and has become a real available resource in the laboratory over recent years. The observation of quantum entanglement in macroscopic matters has implications in the fundamental studies of quantum mechanics, as well as the implementations of quantum information technologies, such as quantum communication, enhanced sensing and distributed quantum computing. Here, we report the creation and storage of the heralded entanglement between two different types of broadband quantum memories located on separated platforms at room temperature: a single-photon entangled state delocalized between billions of motional atoms as a collective excitation and an all-optical loop as a flying qubit. The stored entangled state is subsequently retrieved after a programmable storage time, and is verified by measuring the nonclassical correlations, quantum interference, and concurrence of the mapped-out Raman-scattered photons. Our results show that quantum entanglement can be sustained in macroscopic matters at ambient condition, which pushes the fundamental researches of the transition boundary between quantum and classical worlds. Also, the two quantum memories constitute a hybrid memory-built-in quantum network, which highlights the potential of the cooperation between an stationary atomic ensemble and an all-optical loop as quantum nodes at ambient condition, and brings a significant step towards practical quantum networks.