Pulse, polarization and topology shaping of polariton fluids

Abstract

Here we present different approaches to ultrafast pulse and polarization shaping, based on a "quantum fluid" platform of polaritons. Indeed we exploit the normal modes of two dimensional polariton fluids made of strong coupled quantum well excitons and microcavity photons, by rooting different polarization and topological states into their sub-picosecond Rabi oscillations. Coherent control of two resonant excitation pulses allows us to prepare the desired state of the polariton, taking benefit from its four-component features given by the combination of the two normal modes with the two degrees of polarization. An ultrafast imaging based on the digital off-axis holography technique is implemented to study the polariton complex wavefunction with time and space resolution. We show in order coherent control of the polariton state on the Bloch sphere, an ultrafast polarization sweeping of the Poincaré sphere, and the dynamical twist of full Poincaré states such as the skyrmion on the sphere itself. Finally, we realize a new kind of ultrafast swirling vortices by adding the angular momentum degree of freedom to the two-pulse scheme. These oscillating topology states are characterized by one or more inner phase singularities tubes which spirals around the axis of propagation. The mechanism is devised in the splitting of the vortex into the upper and lower polaritons, resulting in an oscillatory exchange of energy and angular momentum and in the emitted time and space structured photonic packets.

Spiraling vortices in exciton-polariton condensates

“…Polaritons * xuekai.ma@gmail.com may undergo condensation [15,16] and can be excited by both resonant and nonresonant pumping. Under resonant excitation, the pump determines the phase profile of the vortex wave function [10,[17][18][19]. A nonresonant pump with its energy far above the excitonic resonance creates an excitation reservoir that determines the condensate formation dynamics and spatial distribution.…”