Structural Physical Approximation make possible to realize the optimal singlet fraction with two measurements

TL;DR

This paper demonstrates that the optimal singlet fraction can be estimated and realized using structural physical approximation of partial transpose with only two measurements, enabling efficient quantum entanglement applications.

Contribution

It introduces a method to express and realize the optimal singlet fraction via SPA to partial transpose using just two measurements, including Hong-Ou-Mandel interferometry.

Findings

Optimal singlet fraction is linked to the minimum eigenvalue of SPA to partial transpose.

Hong-Ou-Mandel interferometry can realize the optimal singlet fraction with two detectors.

Hybrid entangled states can serve as resources for quantum teleportation.

Abstract

Structural physical approximation (SPA) has been exploited to approximate non-physical operation such as partial transpose. It has already been studied in the context of detection of entanglement and found that if the minimum eigenvalue of SPA to partial transpose is less than $\frac{2}{9}$ then the two-qubit state is entangled. We find application of SPA to partial transpose in the estimation of optimal singlet fraction. We show that optimal singlet fraction can be expressed in terms of minimum eigenvalue of SPA to partial transpose. We also show that optimal singlet fraction can be realized using Hong-Ou-Mandel interferometry with only two detectors. Further we have shown that the generated hybrid entangled state between a qubit and a binary coherent state can be used as a resource state in quantum teleportation.