Quantum Communication with Structured Light in Free-Space Channels

Synopsis

Abstract: The distribution of quantum states is of fundamental importance for the progression of quantum computing and for the future of secure communication through QKD. Photons are the primary tool used for distributing quantum information, but there are many photonic degrees of freedom that can be considered for encoding the information. I will discuss the spatial modes of light, primarily focussing on the OAM carrying Laguerre-Gaussian modes which can be used to encode high-dimensional quantum information. We use these states to perform free-space quantum key distribution in various environments including underwater channels and show the improvements that can be achieved by implementing adaptive optics systems to compensate for atmospheric turbulence. Additionally, we use these high-dimensional states to study new error tolerant protocols for quantum communication. I will also discuss the devices used to generate these spatial modes and the other ways that we can use these devices for generating interesting optical beams. 

Bio: Felix Hufnagel is a PhD student at the University of Ottawa where he focuses on free-space quantum communication in real-world channels. He has studied the use of adaptive optics systems in communication channels to improve key rates and channel fidelity. During his masters, he studied underwater channels for quantum key distribution using polarization, OAM, and vector vortex modes. He has also researched compressed sensing methods for quantum state and process tomography and developed liquid crystal fabrication techniques to create novel optical elements.