  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 demon- strate 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 tur- bulence 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.
