Robert Fickler, University of Vienna
The transverse spatial degree of freedom of light offers great potential to explore quantum informational tasks and interesting features of single photons and quantum entanglement. We developed novel methods to generate, investigate, and verify the entanglement of complex spatial structures. With these methods, we were able to entangle photons with up to 300 quanta of orbital angular momentum (OAM) and to image the effect of entanglement of twisted photons in real-time. With the novel generation and detection scheme it was possible to increase the complexity of the state by entangling photons that show a transverse varying polarization. Interestingly, such photons can be both entangled and not entangled in polarization depending on the transverse position. In recent experiments, we demonstrated an interface between OAM encoded information and the path degree of freedom as well as that spatially encoded information can be transmitted through turbulent atmosphere. Both results allow an optimistic view on a possible future high-dimensional quantum network, where complex on-chip experiments are linked via OAM encoded photons.