  The quantum interface (QI) that generates entanglement between photonic and
spin-wave (atomic memory) qubits is a basic building block for quantum
repeaters. Realizing ensemble-based repeaters in practice requires quantum
memory providing long lifetime and multimode capacity. Significant progresses
have been achieved on these separate goals. The remaining challenge is to
combine long-lived and multimode memories into a single QI. Here, by
establishing multimode, magnetic-field-insensitive and long-wavelength
spin-wave storage in laser-cooled atoms that are placed inside a
phase-passively-stabilized polarization interferometer, we constructed a
multiplexed QI that stores up to three long-lived spin-wave qubits. Using a
feed-forward-controlled system, we demonstrated that the multiplexed QI gives
rise to a 3-fold increase in the atom-photon (photon-photon)
entanglement-generation probability compared to single-mode QIs. The measured
Bell parameter is 2.5+/-0.1 combined with a memory lifetime up to 1ms. The
presented work represents a key step forward in realizing fiber-based
long-distance quantum communications.
