  Recently, it is well recognized that hypothesis testing has deep relations
with other topics in quantum information theory as well as in classical
information theory. These relations enable us to derive precise evaluation in
the finite-length setting. However, such usefulness of hypothesis testing is
not limited to information theoretical topics. For example, it can be used for
verification of entangled state and quantum computer as well as guaranteeing
the security of keys generated via quantum key distribution. In this talk, we
overview these kinds of applications of hypothesis testing.
