Entanglement amplification via local weak measurements

TL;DR

This paper introduces a measurement-based protocol using local weak measurements to probabilistically amplify entanglement, enabling the conversion of partially-entangled states into maximally-entangled states, applicable to both pure and certain mixed states.

Contribution

It presents a novel probabilistic entanglement amplification method via local weak measurements, extending entanglement distillation techniques to single-copy states.

Findings

Probabilistic amplification of entanglement demonstrated.

Success probability linked to initial entanglement level.

Method applicable to specific mixed states with separable parts.

Abstract

We propose a measurement-based method to produce a maximally-entangled state from a partially-entangled pure state. Our goal can be thought of as entanglement distillation from a single copy of a partially-entangled state. The present approach involves local two-outcome weak measurements. We show that application of these local weak measurements leads to a probabilistic amplification of entanglement. In addition, we examine how the probability to find the maximally-entangled state is related to the entanglement of the input state. We also study the application of our method to a mixed initial state. We show that the protocol is successful if the separable part of the mixed initial state fulfils certain conditions.