Quantum information transfer via high-dimensional structured states

Quantum communication is central to future secure networks and the quantum internet. While most implementations rely on polarization entanglement, limited to two-dimensional encoding, high-dimensional states, e.g., based on the orbital angular momentum (OAM) of light, enable richer Hilbert spaces, higher information rates, enhanced security, and increased robustness to noise. This project aims to advance high-dimensional quantum information both fundamentally and experimentally, addressing key questions of coherence, entanglement, and other forms of non-classicality while developing practical free-space quantum links.

Using spatial light modulators and adaptive optics, we will generate, transmit, and detect OAM-entangled photons under realistic atmospheric turbulence. Deep learning algorithms will be employed to pre-compensate distortions in real time, maximizing state fidelity. In order to fully characterize and exploit the high dimensionality of our signals, tools will be developed to certify effective Hilbert-space dimension, quantify coherence and other non-classical resources for single photons, and assess entanglement and non-local properties of multi-photon states. Quantum protocols such as dense coding and quantum random-access codes will be implemented, bridging theory and experiment.

By integrating quantum optics, quantum information theory, and machine learning, the project seeks to establish scalable hybrid spin–orbit quantum links. Free-space connections provide a flexible, energy-efficient complement to fiber networks, while high-dimensional protocols expand both capacity and security. Simultaneously, exploring foundational properties of high-dimensional entanglement will deepen understanding of quantum correlations, guiding the design of robust, high-capacity quantum communication systems. This synergy of practical deployment and fundamental characterization positions the research at the interface of quantum technologies and quantum information science.

The candidate should hold a degree in Physics, or a related discipline. A solid foundation in optics is expected, as well as familiarity with experimental laboratory work. While not strictly required, prior knowledge in one or more of the following areas would be considered an asset:

• Quantum Optics: understanding of polarization, optical anisotropy, and the interaction of light with matter; familiarity with polarimetric methods and optical characterization techniques.
• Quantum Information: basic understanding of quantum states, measurements, and channels. Essentials of information theory. Familiarity with standard protocols such as quantum teleportation, dense coding, and quantum key distribution. Knowledge of matrix analysis, including spectral properties, positive semidefinite matrices, and operator norms, is also desirable.

In addition, the candidate should demonstrate analytical skills, motivation to learn advanced experimental techniques, and the ability to work in an interdisciplinary environment that combines physics and optical engineering. Strong written and oral communication skills in English are also desirable.

The Optics Group at UAB is internationally recognized for its research in image processing, quantum optics, and structured light applications. They specialize in high-dimensional quantum communication protocols, with innovations using nonlinear crystals for entanglement generation and detection. The team currently consists of 3 senior researchers, 1 Ramon y Cajal (RyC) investigator, 1 postdoc, and 4 PhD students.

The project will be carried jointly the The Quantum Information Group (GIQ) at UAB, one of Spain’s pioneering teams in quantum information science. GIQ brings extensive expertise in quantum information theory, quantum communication, entanglement and resource theories, quantum statistical inference, quantum metrology, and quantum machine learning. The group 7 senior researchers (4 full professors), 5 postdoctoral researchers, and 12 PhD students. Its members have a strong international record of publications in leading journals and participation in major conferences and workshops.

The candidate will be expected to actively collaborate with both groups, benefiting from the combined expertise in quantum optics, high-dimensional protocols, and quantum information science, and will have the opportunity to engage with ongoing research in both theoretical and experimental aspects of high-dimensional quantum states.