  Although various physical systems have been explored to produce entangled
states involving electromagnetic, strong, and weak interactions, the gravity
has not yet been touched in practical entanglement generation. Here, we propose
an experimentally feasible scheme for generating spin entangled neutron pairs
via the Earth's gravitational field, whose productivity can be one pair in
every few seconds with the current technology. The scheme is realized by
passing two neutrons through a specific rectangular cavity, where the gravity
adjusts the neutrons into entangled state. This provides a simple and practical
way for the implementation of the test of quantum nonlocality and statistics in
gravitational field.
