Periodic Reporting for period 3 - emergenTopo (Emergent topology in photon fluids)
Periodo di rendicontazione: 2023-06-01 al 2024-11-30
Topology describes the properties of a system that remain unchanged under deformations. An example is the number of holes in a closed surface. As a result, a ring can be continuously deformed to become a mug while keeping the same number of holes: the surfaces of the two objects are characterized by the same topological invariant (the number of holes).
These seemingly abstract concepts can be applied to describe photonic bands in optical materials. One of the most interesting consequences is that at the frontier between two materials of different topology, light is trapped at the interface. These interface states can be used to implement photonic circuits on a micrometric scale and particularly resistant to disorder.
The project emergenTopo aims at going a step further by revealing new topological phases in photonics. One of the goals of the project is to take advantage of the optical nonlinearities present in certain materials to create networks of photonic resonators whose topological invariants depend on the number of photons trapped within them. In this way, their topology can be modified by varying the light intensity with which they are excited. A second goal of the project is to induce new topological phases based on the temporal modulation of the resonator system. In addition to the fundamental interest in the field of topological phases of matter, the expected results will open the way to the design of microchips whose photonic transport could be manipulated at high speed.
These seemingly abstract concepts can be applied to describe photonic bands in optical materials. One of the most interesting consequences is that at the frontier between two materials of different topology, light is trapped at the interface. These interface states can be used to implement photonic circuits on a micrometric scale and particularly resistant to disorder.
The project emergenTopo aims at going a step further by revealing new topological phases in photonics. One of the goals of the project is to take advantage of the optical nonlinearities present in certain materials to create networks of photonic resonators whose topological invariants depend on the number of photons trapped within them. In this way, their topology can be modified by varying the light intensity with which they are excited. A second goal of the project is to induce new topological phases based on the temporal modulation of the resonator system. In addition to the fundamental interest in the field of topological phases of matter, the expected results will open the way to the design of microchips whose photonic transport could be manipulated at high speed.
Most of the equipment required to carry on the action was purchased and installed. From the experimental point of view, we successfully implemented the single shot measurement technique required to study stochastic vorticity in WP1. Regarding WP2, we showed experimentally the possibility of implementing interaction induced magnetic fields in a single micropillar (B. Real et al., Phys. Rev. Research 3, 043161 (2021)). This is a milestone to achieve the rest of the goals of WP2. Work for WP3 was very successful, including the implementation of two fibre rings set-ups to study Floquet topology. We showed that we can measure photonic bands in the system using an original technique (C. Lechevalier et al., Commun. Phys. 4, 243 (2021)).
Both the single shot technique to measure the polariton field with a resolution of 1ps and the technique to measure the band dispersion in coupled fibre rings set the state of the art in their respective domains. Thanks to these techniques we expect unveiling the stochastic vortex dynamics of vortices in a polariton fluid, and novel topological phases in Floquet-Bloch bands. Regarding lattices of coupled micropillars, preliminary experiments in a single pillar anticipate the possibility of implementing nonlinear topological phases.