Nonlocal Activation of Bound Entanglement via Local Quantum Zeno Dynamics

TL;DR

This paper introduces a local quantum Zeno-based method to activate and enhance bound entanglement using only single-particle rotations and threshold measurements, reducing resource requirements compared to previous schemes.

Contribution

The authors propose a novel local quantum Zeno scheme that activates bound entanglement with minimal resources, requiring only single-particle operations and a single classical communication.

Findings

Negativity increased from 0.11 to 0.17 with one bound-entangled state.

Negativity exceeded 0.42 using four additional bound-entangled states.

Fidelity to maximally entangled state improved from 0.3 to 0.61.

Abstract

Bound entanglement was shown to be activated [P. Horodecki \textit{et al.,} Phys. Rev. Lett. \textbf{82,} 1056 (1999)] in the sense that the entanglement of a spatially separated two-qutrit system can be increased with nonzero probability via a sufficiently large number of preshared 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 a large number of bound-entangled states nor controlled operations 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 by using four more bound-entangled states, negativity can be made greater than 0.42 and the fidelity to the maximally entangled state increases from 0.3 to 0.41, 0.50, 0.59, and 0.61. We believe our results are important not only for quantum technologies but also for a better understanding of quantum entanglement.