  Entanglement plays a central role in the field of quantum information
science. It is well known that the degree of entanglement cannot be increased
under local operations. Here, we show that the concurrence of a bipartite
entangled state can be increased under the local PT -symmetric operation. This
violates the property of entanglement monotonicity. We also use the Bell-CHSH
and steering inequalities to explore this phenomenon.
