We are looking for a **PhD student in experimental nonlinear optics** with the prospect of pursuing a scientific/industry career.

**The project aims at studying topological properties of lattices of photonic resonators**. Topology describes properties of a physical system that remain unaffected by distortion. The simplest example is the “genus”: the number of holes in the surface of an object. For instance, a mug and a donut both have a hole, they both belong to the same topological class (genus=1) and they can be transformed into each other via smooth deformations. The only way of modifying the topological class is by closing the hole (genus=0) or opening an extra one (genus=2). The application of these concepts to solid state physics allowed explaining the quantized transport in the quantum Hall effect, and its robustness to disorder and local deformations of Hall bar. Its growing importance was recognized by the 2016 Nobel Prize Kortelitz, Thouless and Haldene.

In photonics, topology is opening a new field in which the use of “photonic topological materials” will allow the manipulation of light down to the micrometric scale with properties intrinsically robust to noise, disorder and defects.

In this experimental PhD thesis, we propose the engineering and study of photonic systems with topological properties. We will employ lattices of microcavity polaritons, an example of which is shown in the left panel of the figure [M. Milicevic et al., PRL **118**, 107403 (2017)]. In this hexagonal lattice photons behave as electrons in graphene, and the system possess states localised at the edges that emerge from the topological properties of the lattice. Using a similar configuration, we have recently implemented a 1D topological laser [P. St-Jean et al., Nat. Photon. **11**, 651 (2017)]. One of the goals of the thesis will be to implement chiral edge states in 2D lattices with photonic transport robust to backscattering and to study nonlinear topological phenomena that emerges when photon interactions are considered.

The thesis will be developed in an optics microscopy laboratory, at the crossroads of quantum simulation and optics, and it will be done closed collaboration with theoretical groups involved in international projects. It will take advantage of the continuity of an ERC grant leaded by A. Amo on the implementation of topological properties in polariton systems.

More info on the group activities: http://honeypol.eu/

The PhD project involves:

- Design, perform and analyse optical experiments in polariton lattices.
- Participate in the ongoing collaborations with theoreticians in several groups in Europe.
- Present the results at international conferences.

Requirements:

- Master degree in Physics or equivalent by the date of start of the thesis.
- Notions of quantum mechanics.
- Knowledge of English.

**Duration:** 3 years

**Starting date:** October 2018

**If you are interested, send your CV and motivation letter in English to: **alberto.amo (at) univ-lille1.fr