  Establishing a quantum interface between different physical systems is of
special importance for developing the practical versatile quantum networks.
Entanglement between low- and high-lying atomic spin waves is essential for
building up Rydberg-based quantum information engineering, otherwhile be more
helpful to study the dynamics behavior of entanglement under external pertur-
bations. Here, we report on the successful storage of a single photon as a
high-lying atomic spin wave in quantum regime. Via storing a K-vector
entanglement between single photon and lowly lying spin wave, we thereby
experimentally realize the entanglement between low- and high-lying atomic spin
waves in two separated atomic systems. This makes our experiment the primary
demonstration of Rydberg quantum memory of entanglement, making a primary step
toward the construction of a hybrid quantum interface.

Quantum Physics