  Entanglement is a crucial quantum resource with broad applications in quantum
information science. For harnessing entanglement in practice, it is a
prerequisite to certify the entanglement of a given quantum state. However, the
certification process itself destroys the entanglement, thereby precluding
further exploitation of the entanglement. Resolving this conflict, here we
present a protocol that certifies the entanglement of a quantum state without
complete destruction, and then, probabilistically recovers the original
entanglement to provide useful entanglement for further quantum applications.
We experimentally demonstrate this protocol in a photonic quantum system, and
highlight its usefulness for selecting high-quality entanglement from a
realistic entanglement source. Moreover, our study reveals various tradeoff
relations among the physical quantities involved in the protocol. Our results
show how entanglement certification can be made compatible with subsequent
quantum applications, and more importantly, be beneficial to sort entanglement
for better performance in quantum technologies.
