Effect of Aberrations on 3D optical topologies

TL;DR

This study experimentally investigates how optical phase aberrations affect 3D optical topologies like knots and links, revealing their robustness under certain disturbances and implications for secure information processing.

Contribution

It provides the first experimental analysis of the robustness of optical knots and links under phase aberrations, highlighting their potential in noisy quantum and classical communication channels.

Findings

Optical knots show remarkable robustness under misalignment and phase aberrations.

High aberration strengths can obliterate the topological structures.

Results suggest potential applications in secure and resilient optical information processing.

Abstract

Optical knots and links, consisting of trajectories of phase or polarisation singularities, are intriguing nontrivial three-dimensional topologies. They are theoretically predicted and experimentally observed in paraxial and non-paraxial regimes, as well as in random and speckle fields. Framed and nested knots can be employed in security protocols for secret key sharing, quantum money, and topological quantum computation. The topological nature of optical knots suggests that environmental disturbances should not alter their topology; therefore, they may be utilised as a resilient vector of information. Hitherto, the robustness of these nontrivial topologies under typical disturbances encountered in optical experiments has not been investigated. Here, we provide the experimental analysis of the effect of optical phase aberrations on optical knots and links. We demonstrate that Hopf links, trefoil and cinquefoil knots exhibit remarkable robustness under misalignment and phase aberrations. The observed knots are obliterated for high aberration strengths and defining apertures close to the characteristic optical beam size. Our observations recommend employing these photonics topological structures in both classical and quantum information processing in noisy channels where optical modes are strongly affected and not applicable.