RESUMO
Spatially confined, trapped polariton condensates have been shown to exhibit strong stochastic on-site spin polarization and in longer polariton condensate chains, distance controlled ferromagnetic and antiferromagnetic spin couplings. Until now, little is known, on how such polariton condensates spatially separated from their exciton reservoirs are trapped and formed. Here, we investigate the properties and formation dynamics of two main families of polariton condensates, those overlapping with the pump reservoir and those in confined geometries, under pulsed nonresonant excitation. The observed reduction in polariton condensation threshold and energy blueshift in trapped case is attributed to exciton reservoir-condensate spatial separation, whereas time-resolved photoluminescence measurements, reveal distinct relaxation and condensate formation dynamics with pair parametric scattering process being the dominant relaxation mechanism in trapped geometry.
RESUMO
A primary limitation of the intensively researched polaritonic systems compared to their atomic counterparts for the study of strongly correlated phenomena and many-body physics is their relatively weak two-particle interactions compared to disorder. Here, we show how new opportunities to enhance such on-site interactions and nonlinearities arise by tuning the exciton-polariton dipole moment in electrically biased semiconductor microcavities incorporating wide quantum wells. The applied field results in a twofold enhancement of exciton-exciton interactions as well as more efficiently driving relaxation towards low energy polariton states, thus, reducing condensation threshold.