Entanglement Enhanced Detection

Yan Li, Zhihong Ren

Cornelius Hempel, B. P. Lanyon, Petar Jurcevic +3 more

Otfried Gühne, Géza Tóth

John Rarity, Bryn A. Bell, A. B. Young +1 more

We introduce the concept of entanglement enhanced interferometry from the viewpoint of the detected photons. The standard quantum limit is achieved when sequentially detected photons are assumed to be in an uncorrelated product state. However when we access the correlations between the detected photons that existed before the interferometer it becomes clear that entanglement enhanced measurement beyond the quantum limit could be achieved independent of loss. We describe possible realisations of this post-measurement entanglement detection using a small array of spin photon entangling gates. We then describe a proof of principle experiment using only linear optics resources.

Dagmar Bruβ

Haruki Matsunaga, Le Bin Ho

We propose an innovative method to enhance the detection and protection of quantum entanglement, a cornerstone of quantum mechanics with applications in computing, communication, and beyond. While entanglement can be represented through nonlocal correlations detectable by the Clauser-Horne-Shimony-Holt (CHSH) inequality, this method does not fully capture all entangled states. To address this limitation, we introduce a variational entanglement witness (VEW) that optimizes the probabilities of detection and improves the efficiency of distinguishing between separable and entangled states. Additionally, we propose a nonlocal measurement framework that enables the assessment of both CHSH inequalities and the VEW while preserving the entanglement. Our approach enhances the reliability of entanglement detection while maintaining the entanglement of quantum states, offering significant advancements for quantum technologies.