Observing the decay of orbital angular momentum entanglement, through experimentally simulated turbulence

TL;DR

This study experimentally investigates how atmospheric turbulence affects the entanglement of photons carrying orbital angular momentum, confirming theoretical predictions and analyzing implications for free-space quantum communication.

Contribution

First experimental confirmation of entanglement decay due to atmospheric turbulence using quantum state tomography and concurrence measurement.

Findings

Entanglement decreases with increasing turbulence strength.

Modal scattering increases as scintillation intensifies.

Entanglement dissipation scale impacts free-space quantum communication.

Abstract

We study the evolution of an orbital angular momentum (OAM) entangled bipartite photonic state for the case where one of the photons propagates through Kolmogorov turbulence, using the concurrence as a measure of entanglement. Quantum state tomography was performed to reconstruct the two qubit density matrices for a range of scintillation strengths. Our results give the first direct experimental confirmation of the existing theories for decay of entanglement due to atmospheric turbulence. We also show how the modal scattering increases with increasing scintillation and we discuss the impact of the scale at which entanglement dissipates due to atmospheric turbulence on free-space quantum communication.