High-dimensional frequency conversion in hot atomic system

TL;DR

This paper demonstrates a high-dimensional frequency converter for perfect optical vortex modes using four-wave mixing in hot atomic vapor, achieving high efficiency and fidelity across multiple dimensions, with potential for quantum communication.

Contribution

It introduces a novel frequency conversion scheme for POV modes with invariant size, overcoming limitations of conventional optical vortex modes, and demonstrates high fidelity in multiple dimensions.

Findings

Conversion efficiency is independent of topological charge l in the specified subspace.

Fidelities for 2D superposed POV states exceed 97%.

High-dimensional superposition states (3D, 5D, 7D) are converted with fidelities above 88%.

Abstract

One of the major difficulties in realizing a high-dimensional frequency converter for conventional optical vortex (COV) stems from the difference in ring diameter of COV modes with different topological charge numbers l. Here, we implement a high-dimensional frequency convertor for perfect optical vortex (POV) modes with invariant size through the four-wave mixing (FWM) process by utilizing Bessel-Gaussian beams instead of Laguerre-Gaussian beams. The measured conversion efficiency from 1530 nm to 795 nm is independent of l at least in subspace of {-6,...,6}, and the achieved conversion fidelities for two-dimensional (2D) superposed POV states exceed 97%. We further realize the frequency conversion of 3D, 5D and 7D superposition states with fidelities as high as 96.70%, 89.16% and 88.68%, respectively. The reported scheme is implemented in hot atomic vapor, it's also compatible with the cold atomic system and may find applications in high-capacity and long-distance quantum communication.