Atmospheric Turbulence and Orbital Angular Momentum of Single Photons for Optical Communication

Abstract

The effects of propagation through random aberrations on coherence for single-photon communication systems based on orbital angular momentum states are quantified. A rotational coherence function is derived which leads to scattering equations for azimuthal modes of different orbital angular momentum states. The effect on a single-photon communication system is quantified using the channel capacity. The work shows that the decoherence effect of atmospheric turbulence on such systems is important even for weak turbulence.

Orbital-angular-momentum entanglement in turbulence

“…Previous theoretical studies of the effects of atmospheric turbulence on the OAM modes have considered the effect of turbulence on the detection probability of OAM modes [6,11,12], the attenuation and crosstalk among multiple OAM channels [13] and the decay of entanglement for bipartite qubits [14,15]. These studies are all based on the Paterson model using a single phase screen [6] with the exception of the analytical study presented in [15] and the numerical study in [13] which are both based on a multiple phase screen approach.…”

“…In view of the increased storage capacity per photon and the corresponding new potential quantum communication protocols, OAM entangled photons are candidate carriers for long-range quantum communication [6] and higher dimensional quantum key distribution [7]. So far, protocols to achieve long-range quantum communication are based on the distribution of quantum correlations (entanglement) between the nodes of a network combined with teleportation of these correlations from one node to the next, a process also known as entanglement swapping [8][9][10].…”

“…These studies are all based on the Paterson model using a single phase screen [6] with the exception of the analytical study presented in [15] and the numerical study in [13] which are both based on a multiple phase screen approach.…”

Self-healing of quantum entanglement after an obstruction

“…There have also been theoretical suggestions to recover lost entanglement 18 ; however, it is yet to be demonstrated experimentally. In the context of OAM modes, the decay of entanglement has been both predicted 19 and measured 20 for atmospheric turbulence as an environment, with some success in diminishing these effects [21][22][23] .…”

Massive individual orbital angular momentum channels for multiplexing enabled by Dammann gratings

“…To estimate the performance of OAM-based MUX/DEMUX technology for long-distance FSO, we model the OAM beams' propagation in an atmosphere based on the Kolmogorov turbulence theory. [29][30][31][32][33] We take the random intensity and phase perturbation of OAM beams into account and calculate the crosstalk among the OAM states. We define S mn as the percentage of beam energy transferred from the OAM state m to n. While m5n, S mn is the power remaining in the original OAM state m; while m?n, S mn is the crosstalk between OAM states m and n. We define C 2 n as the refractive-index structure parameter with a unit of m 22/3 , which is related to the strength of turbulence in the atmosphere.…”