Universal entanglement losses induced by angular uncertainty

TL;DR

This paper investigates how diffraction through angular apertures causes entanglement loss in photon pairs with orbital angular momentum, revealing a universal law dependent on angular uncertainty and initial angular momentum.

Contribution

It introduces a universal law describing entanglement degradation due to diffraction, based on angular uncertainty and initial angular momentum, applicable to photonic qubits.

Findings

Entanglement loss follows a universal law parametrized by $l_0\Delta \,phi$.

Diffraction-induced entanglement degradation can be quantitatively predicted.

The study links angular uncertainty with entanglement degradation in a universal framework.

Abstract

We study the diffraction of two maximally entangled qubits encoded into spatial modes of light with orbital angular momenta $\pm \hbar l_0$, on angular apertures. Exploiting the uncertainty relation between angular position and momentum, we quantify the diffraction-induced entanglement loss, for different $l_0$, as a function of the angular uncertainty $\Delta \phi$ induced by the apertures. We demonstrate that the degradation of entanglement follows a universal law parametrised by the product $l_0\Delta \phi$ alone.} {We study the diffraction of two photonic qubits, which are initially maximally entangled in their orbital angular momenta, on angular apertures. Using the uncertainty relation between angular position and momentum, we show that the diffraction-induced entanglement losses exhibit universal behaviour.