28 July 2020 Tue 4 pm

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Exciton-polariton system in semiconductor heterostructures have unique properties due to the combination of all-optical control of the wave function and strong nonlinear interaction, stemming from the exciton component. The latter originates such complex topological condensate excitations as quantum vortices and solitons. In the first part of the talk, the narrow 1D channels with the walls of high condensate density at the upper bistability branch created by intensive laser radiation are studied. It was demonstrated that in such channels dark solitons appear parallel to the channel axis by odd (1-3) or even (2-4) number in order to accommodate the phase constraint induced in the walls. These soliton molecules are typically unstable and evolve toward symmetric or anti-symmetric arrays of vortex streets. Inspired by this phenomenon,  the soliton spatial propagation in the all-optically patterned maze was studied and the essential feature of maze solving was demonstrated. In the second part, the existence of the energy cascade in 2D quantum turbulence, which is one of the open questions in the physics of quantum fluids is considered. The shape of raw energy spectra depends on the procedure of condensate stirring but the energy spectra of clustered vortices always exhibit the -5/3 power law. Such cascade can be observed over almost 2 decades.