Nonlinear and quantum properties of hybrid light-matter interacting states in semiconductor photonic structures. PHY-09-Krizhanovskii

Recent advances in semiconductor nano-technology have led to a new generation of robust controllable structures where manipulation of coupling between light and matter can be performed on a sub-micrometer scale. In these structures photons may hybridize with electronic excitations (excitons) in semiconductor optically active materials (such as (In)GaAs, transition metal dichalcogenides, perovskites and others), which leads to novel quasiparticles –so-called polaritons. In two-dimensional photonic micro resonators the photonic dispersion is nearly parabolic and hence photons ( as well as polaritons) have a finite, but a very small effective mass. Therefore, polaritons may exhibit condensation into a single macroscopically occupied quantum state at high temperatures up to 300 K. Polariton macroscopically occupied states may exhibit properties, which are similar to as well as strongly distinct from those of atomic Bose-Einstein condensates. In addition, while photons propagating in free space do not interact, the excitonic component in the polariton wavefunction enables strong effective polariton-polariton interactions. Such a nonlinearity is potentially useful for development of nonlinear and quantum optical devices and integrated circuits, enabling control of photonic signals by light of very small intensity (down to a single photon level) and on very small length scale of a few micrometers. Furthermore, this nonlinearity gives rise to rich phenomena ranging from superfluidity of light (i.e propagation of light in a media without scattering by imperfections), ultra-low power self-localised wave packets (solitons) to generation of single photons and entangled photon pairs.

This project concerns the experimental investigation of polaritons in planar two-dimensional micro resonators and lattices of coupled zero-dimensional micro resonators. A particular emphasis will be placed on the study of topologically protected polariton states and novel non-equilibrium condensate phases in these structures. You will explore how the effects of gain and loss under external laser pumping, lattice geometry and giant optical nonlinearity influence the polariton topology, the 1st and 2nd order temporal and spatial coherence and ultrafast polariton dynamics. You will focus on the study of polariton phases in structures based on GaAs and atomically thin layers of transition metal dichalcogenides materials (2D materials of MoSe2, WSe2 and others). The growth technology of GaAs-based photonic structures is well developed and enables fabrication of high quality devices with long polariton lifetimes and good spatial homogeneity, which is essential for the realization of novel exotic nonequilibrium polariton condensates aimed in this project. While technological processes for fabrication of 2D material heterostructures are still developing, the much stronger light-matter coupling, interesting k-space valley and spin properties and interaction with (anti)ferromagnetic states in some of these 2D materials paves the way towards novel physics and applications, not accessible in GaAs-based structures.

Overall, polariton physics in microcavities is very topical research which may find future applications in quantum optical computation and simulations.

A successful candidate will join a well-funded and very active research group with a world-wide reputation for excellence (https://ldsd.group.shef.ac.uk/research/polaritons/). The group possesses a wide range of modern equipment to conduct advanced quantum optics experiments. During the project the student will also obtain full access to a state-of-the-art clean room facilities available in Sheffield.

Application forms can be found here https://www.sheffield.ac.uk/arpform/login.app?code=EPSRC

Interested candidates are strongly encouraged to contact the project supervisors to discuss your interest in and suitability for the project prior to submitting your application. 

Please refer to the EPSRC DTP webpage for detailed information about the EPSRC DTP and how to apply.