Recovery of resources through sequential noisy measurements

TL;DR

This paper shows that sequential noisy measurements can recover and concentrate entanglement in quantum networks, mitigating noise effects and enhancing control over quantum resources for communication.

Contribution

It introduces a method of using sequential unsharp measurements to preserve and localize entanglement, outperforming traditional projective measurement approaches.

Findings

Sequential measurements recover entanglement comparable to projective measurements.

The approach enables preparation of resource states for quantum schemes.

Assisting qubits offer greater control over entanglement concentration.

Abstract

Noisy unsharp measurements incorporated in quantum information protocols may hinder performance, reducing the quantum advantage. However, we show that, unlike projective measurements which completely destroy quantum correlations between nodes in quantum networks, sequential applications of noisy measurements can mitigate the adverse impact of noise in the measurement device on quantum information processing tasks. We demonstrate this in the case of concentrating entanglement on chosen nodes in quantum networks via noisy measurements performed by assisting qubits. In the case of networks with a cluster of three or higher number of qubits, we exhibit that sequentially performing optimal unsharp measurements on the assisting qubits yields localizable entanglement between two nodes akin to that obtained by optimal projective measurements on the same assisting qubits. Furthermore, we find that the proposed approach using consecutive noisy measurements can potentially be used to prepare desired states that are resource for specific quantum schemes. We also argue that assisting qubits have greater control over the qubits on which entanglement is concentrated via unsharp measurements, in contrast to sharp measurement-based protocols, which may have implications for secure quantum communication.