Entangling motional atoms and an optical loop at ambient condition

Abstract

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 of the heralded entanglement between two different room-temperature quantum memories: a single-photon entangled state delocalized between motional atoms as a collective excitation and an all-optical loop as a flying qubit. The stored entangled state is subsequently retrieved and verified by measuring the nonclassical correlations, quantum interference, and concurrence of the mapped-out photons. Our results show that quantum entanglement can be sustained in macroscopic matters at ambient condition, which enriches the fundamental researches of the transition boundary between quantum and classical worlds. Also, it highlights the potential cooperation between atomic ensembles and all-optical loop as quantum nodes at ambient condition, bringing a significant step towards practical quantum networks.