  The quantum repeater protocol is a promising approach to implement
long-distance quantum communication and large-scale quantum networks. A key
idea of the quantum repeater protocol is to use long-lived quantum memories to
achieve efficient entanglement connection between different repeater segments
with a polynomial scaling. Here we report an experiment which realizes
efficient connection of two quantum repeater segments via on-demand
entanglement swapping by the use of two atomic quantum memories with storage
time of tens of milliseconds. With the memory enhancement, scaling-changing
acceleration is demonstrated in the rate for a successful entanglement
connection. The experimental realization of entanglement connection of two
quantum repeater segments with an efficient memory-enhanced scaling
demonstrates a key advantage of the quantum repeater protocol, which makes a
cornerstone towards future large-scale quantum networks.
