Purifying entanglement of noisy two-qubit states via entanglement swapping

TL;DR

This paper demonstrates that entanglement swapping can recover and purify entanglement in noisy two-qubit states affected by amplitude damping, enabling some states to become maximally entangled through iteration.

Contribution

The authors introduce a protocol using entanglement swapping to purify entanglement in noisy two-qubit states affected by amplitude damping, with iterative application achieving asymptotic maximization.

Findings

Entanglement can be recovered from amplitude damping noise via swapping.

Some initial states can be asymptotically purified into maximally entangled states.

The protocol enables iterative purification of entanglement in noisy environments.

Abstract

Two qubits in pure entangled states going through separate paths and interacting with their own individual environments will gradually lose their entanglement. Here we show that the entanglement change of a two-qubit state due to amplitude damping noises can be recovered by entanglement swapping. Some initial states can be asymptotically purified into maximally entangled states by iteratively using our protocol.