Exciton polaritons offer a promising platform for realising practical applications of macroscopic quantum states at ambient conditions. Formed by the strong mixing of light (photons in a cavity) and matter (excitons in a semiconductor), these particles inherit very low effective mass from photons and strong interparticle interactions from excitons. This combination enables the formation of Bose-Einstein condensates and superfluids at room temperature in a solid-state device.
However, there are two main roadblocks towards future applications of exciton-polariton condensates and superfluids: (1) neutral charge and (2) losses. Unlike paired electrons in superconductors, exciton polaritons are charge-neutral, and hence weakly interact with electromagnetic fields, needing very strong magnetic fields (>5 T) to significantly influence the particles. Moreover, the system is inherently lossy due to photonic losses through the imperfect mirrors forming the cavity.
The project aims to tackle the first problem while taking advantage of the second. Instead of real electromagnetic fields, synthetic gauge fields will be used that are induced by engineering the photonic component of the system. This will be realised by embedding linear or circularly birefringent materials, or metamaterials into the cavity spacer. Moreover, the synthetic fields will be non-Hermitian due to the inherent losses and can be engineered to additionally feature counter-intuitive effects, e.g. similar to loss-induced lasing, that are not possible in lossless systems.
Students involved in the project will work on modelling the optical response of the microcavity, fabrication of actual samples, and/or experimentally probing the emergent synthetic fields and investigating their effects on exciton polaritons.
Fundamentals of condensed matter physics, quantum physics, and optics are desirable, but not essential.