Nonlocal Activation of Bound Entanglement via Local Quantum Zeno Dynamics.

Bound entanglement was shown to be activated [Phys. Rev. Lett., 82, 1056 (1999)] in the sense that the entanglement of a spatially separated two-qutrit system can be increased with a nonzero probability via sufficiently large number of pre-shared bound entangled states, local three-level controlled-operations and classical communications. Here, we present a local quantum Zeno scheme for activating bound entanglement which is based only on single particle rotations and threshold measurements. In our scheme, neither controlled operations nor a large number of bound entangled states are required, and classical communication is required only once at the end of the protocol. We show that a single bound entangled state is sufficient for increasing the negativity of the target entangled state from 0.11 to 0.17, and spending four more bound entangled states, negativity can be made greater than 0.42. We believe our results are important not only for quantum technologies but also for understanding the fundamentals of quantum mechanics.