# Universal entanglement decay of photonic orbital angular momentum qubit states in atmospheric turbulence: an analytical treatment

## TL;DR

This paper provides an analytical study of how entanglement in photonic orbital angular momentum qubits decays in atmospheric turbulence, revealing universal decay laws for different turbulence models.

## Contribution

It derives analytical expressions for mode crosstalk and establishes universal entanglement decay laws under atmospheric turbulence models.

## Key findings

- Analytical expressions for turbulence-induced crosstalk between modes.
- Universal entanglement decay laws for Kolmogorov turbulence.
- Distinct decay behaviors for different turbulence approximations.

## Abstract

We study the entanglement evolution of photonic orbital angular momentum qubit states with opposite azimuthal indices $l_0$, in a weakly turbulent atmosphere. Using asymptotic methods, we deduce analytical expressions for the amplitude of turbulence-induced crosstalk between the modes $l_0$ and $-l_0$. Furthermore, we analytically establish distinct, universal entanglement decay laws for Kolmogorov's turbulence model and for two approximations thereof.