Beating the Optimal Verification of Entangled States via Collective Strategies

TL;DR

This paper introduces a collective verification scheme for entangled states that surpasses traditional methods in efficiency, scalability, and resource usage, with broad applicability in quantum information processing.

Contribution

The authors develop a novel collective verification protocol that outperforms optimal global measurement strategies, scalable for large systems, and preserves unmeasured states.

Findings

Achieves higher efficiency than optimal verification with global measurements

Requires only a few copies of entangled states, preserving unmeasured ones

Provides insights into noise types affecting the system

Abstract

In the realm of quantum information processing, the efficient characterization of entangled states poses an overwhelming challenge, rendering the traditional methods including quantum tomography unfeasible and impractical. To tackle this problem, we propose a new verification scheme using collective strategies, showcasing arbitrarily high efficiency that beats the optimal verification with global measurements. Our collective scheme can be implemented in various experimental platforms and scalable for large systems with a linear scaling on hardware requirement, and distributed operations are allowed. Notably, larger ensembles can always improve the efficiency further, but without increasing the quantum memory. More importantly, the approach consumes only a few copies of the entangled states, while ensuring the preservation of unmeasured ones, and even boosting their fidelity for any subsequent tasks. Furthermore, our protocol provides additional insight into the specific types of noise affecting the system, thereby facilitating potential targeted improvements. These advancements hold promise for a wide range of applications, offering a pathway towards more robust and efficient quantum information processing.