Increase of entanglement by local<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="script">PT</mml:mi></mml:math>-symmetric operations

Abstract

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 $\mathcal{PT}$-symmetric operation. This violates the property of entanglement monotonicity. We also use the Bell--Clauser-Horne-Shimony-Holt and steering inequalities to explore this phenomenon.