Recent schemes to encode quantum information into the total angular momentum
of light, defining rotation-invariant hybrid qubits composed of the
polarization and orbital angular momentum degrees of freedom, present
interesting applications for quantum information technology. However, there
remains the question as to how detrimental effects such as random spatial
perturbations affect these encodings. Here, we demonstrate that alignment-free
quantum communication through a turbulent channel based on hybrid qubits can
be achieved with unit transmission fidelity. In our experiment, alignment-free
qubits are produced with q-plates and sent through a homemade turbulence
chamber. The decoding procedure, also realized with q-plates, relies on both
degrees of freedom and renders an intrinsic error-filtering mechanism that
maps errors into losses