Recovery of local entanglement in self-healing vector vortex Bessel beams

TL;DR

This paper demonstrates that the local entanglement between spatial and polarization degrees of freedom in vector vortex Bessel beams can self-heal after obstruction, recovering its maximum value within the classical self-healing distance.

Contribution

It shows that non-separability or local entanglement in vector vortex Bessel beams can recover after obstruction, extending the understanding of self-healing properties to quantum correlations.

Findings

Non-separability reduces after obstruction but recovers within the self-healing distance.

Bell-like inequality measurement confirms the recovery of non-separability.

Local entanglement can be recovered by choosing the appropriate wave function envelope.

Abstract

One of the most captivating properties of diffraction-free optical fields is their ability to reconstruct upon propagation in the presence of an obstacle both, classically and in the quantum regime. Here we demonstrate that the local entanglement, or non-separability, between the spatial and polarisation degrees of freedom also experience self-healing. We measured and quantified the degree of non-separability between the two degrees of freedom when propagating behind various obstructions, which were generated digitally. Experimental results show that even though the degree of non-separability reduces after the obstruction, it recovers to its maximum value within the classical self-healing distance. To confirm our findings, we performed a Clauser-Horne-Shimony-Holt Bell-like inequality measurement, proving the self-reconstruction of non-separability. These results indicate that local entanglement between internal degrees of freedom of a photon, can be recovered by suitable choice of the enveloping wave function.