Friday 08 Oct 2021: High-dimensional quantum photonics: Pushing the limits of quantum technologies
Mehul Malik - Heriot Watt University
High-dimensional photonic entanglement offers the potential for noise-robust, device-independent quantum networks that harness the full information carrying capacity of a photon. A central challenge in the realisation of such networks is the ability to efficiently measure and reliably transport high-dimensional entangled states of light. In this talk, I will address these two challenges. First, I will discuss a recent experiment on the generation and certification of high-dimensional “pixel” entanglement with a record quality, speed, and dimensionality. Working with the transverse spatial degree-of-freedom of two photons, we demonstrate an entangled state fidelity of greater than 94% in a 19x19-dimensional space, and entanglement in up to 55x55 macro-pixel dimensions. Second, I will discuss an experiment where we transport high-dimensional pixel entanglement through a complex scattering medium: a 2m section of commercial multi-mode fibre. Using the quantum mechanical principle of state-channel duality, entanglement is used to measure the transmission matrix of the complex medium by mapping it onto a maximally entangled state. Furthermore, by using a property unique to high-dimensional entanglement, the medium is rendered transparent to entanglement by carefully “scrambling” the photon that did not enter it, rather than unscrambling the photon that did. Our work overcomes a primary challenge in the fields of quantum communication and imaging, and opens a new pathway towards the control of complex scattering processes in the quantum regime.