Quantum topological polaritonics
The recently proposed idea of topological band classification in photonic crystals has led to the prediction and observation of
topologically nontrivial photonic phases, phenomenologically similar to Quantum Hall and Quantum Spin Hall electronic
phases, and to the development of a new field in physics – topological photonics. Photons at the edges of topologically
nontrivial photonic crystals are protected from backscattering and can be used for unidirectional guiding of light, which is
extremely promising for optical logical device applications and for future optical computers. These ideas have recently given
a new dimension to the field of polaritonics, which is the semiconductor optics equivalent of cavity quantum electrodynamics,
where bound electron-hole pairs, or excitons, are strongly coupled to cavity photons to give rise to interacting quasiparticles:
polaritons. Topological polaritonic states were shown to emerge in nanostructured microcavities solely from polariton
repulsive interactions and can be controlled by optical means, contrary to the purely photonic case. In contrast to electronic
and photonic topological physics, quantum topological polaritonics combines strong nonlinear and non-Hermitian quantum
effects that remain to be explored. This project will provide the fundamental theory basis for quantum topological
polaritonics, a new emerging field that unites topological photonics with polaritonics. The applicant, in collaboration with the
host group, will develop the geometric theory and the topological classification of polaritonic states, accounting for their
strongly nonlinear and non-Hermitian nature. He will also apply this theory to the experimentally studied polaritonic systems
with potential impact on optical devices of the future.