Resilience of hybrid optical angular momentum qubits to turbulence

Abstract

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.

Open-system dynamics of entanglement:a key issues review

“…An interesting direction to explore is the investigation of effective channels for logical encodings relevant to current quantum computing or communication experiments. These may be for instance few-qubit decoherencefree subspaces under realistic noise models for iontrap [471,472] or superconducting-circuit [473,474] architectures, or photonic encodings involving transverse spatial modes, useful for misalignment-immune quantum communication [475][476][477][478], ultra-sensitive rotational sensors [479,480], or high-dimensional qudit processing [479][480][481][482], under atmospheric turbulence or other spatial perturbations [477,483,484].…”

Q-plate technology: a progress review [Invited]

“…So far, this was proven to be feasible, at least in the weak turbulence regime. In this intermediate regime a transmission fidelity close to unity was achieved for rotational invariant qubits [32,77]. This robustness is due mainly to logical encoding and decoding procedures, both based on q-plates.…”

Instrumentation limitation on a polarization-based entangled photon source

“…To overcome the effects of turbulence, as well as the necessity for a shared reference frame, hybrid orbital angular momentum (OAM) and polarization qubit states have been suggested as possible carriers providing a more robust means of communication. The aforementioned hybrid states are rotation-invariant and have been exploited to demonstrate alignment-free, robust quantum communication where qubits are encoded in the two degrees of freedom that are entangled [36][37][38][39]. Thus far, channels with two-dimensional quantum states have been demonstrated over 144 km, between the Tenerife and La Palma Island, using polarization for the encoding [5].This has also been achieved with hybrid OAM and polarization states over a distance of 210 m in a controlled environment to minimize turbulence [38] and lately over 3 km across Vienna [40].…”