Polariton condensate trapping by parametric pair scattering

Abstract

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.

Bogoliubov excitations of a polariton condensate in dynamical equilibrium with an incoherent reservoir

“…We investigate polaritons in the regime of bosonic condensation in an optically induced potential trap [23,26,27,58,61] -see Fig. 4.…”

“…7(a,b). This could be favored by the circular ring pump geometry, which allows additional parametric pair scattering processes to participate in the polariton relaxation within the trap compared to a Gaussian pump spot [26]. Moreover, the momentum occupations are not symmetric with respect to k = 0 and one has N N B(GB),k = N N B(GB),−k [see Fig.…”

“…Thus, polariton condensation is necessarily accompanied by the formation of an incoherent uncondensed excitonic reservoir [8]. Such a reservoir can also manifest itself indirectly in experiments via its repulsive interactions with polaritons [19][20][21][22], allowing the creation of on-demand trapping potentials by spatially selective laser excitation [23][24][25][26][27].…”

Nonlinear Parametric Scattering of Exciton Polaritons in Perovskite Microcavities

“…16,17 Moving toward the technological applications, polariton parametric scattering has been applied to design advanced spectroscopic techniques, 18 electro-optic switches, 19 polariton amplifiers, 12 and traps for polariton condensates. 20 However, such phenomena and applications still demand cryogenic temperatures due to the small exciton binding energies of traditional semiconductor microcavities.…”

“…Exciton polaritons are composites of light and matter, possessing a nonlinearity orders of magnitude stronger than traditional nonlinear optical systems. − Such nonlinearity plays essential roles not only in conceptual polaritonic devices such as neuromorphic computing, transistors, and amplifiers , but also in reaching the nonlinear quantum regime emerging with a polariton blockade , and proposed quantum simulators . The effect of such nonlinearity was first demonstrated with the observation of a polariton parametric oscillation in GaAs or CdTe based quantum well samples, ,,, which was the key milestone underlying the nonlinear exciton-polariton physics as well as the technological applications. , From the fundamental physics point of view, a polariton parametric oscillation can support the stable localization of solitons, , promote overcoming the bottleneck in polariton condensation, and allow the spontaneous formation of quantized vortices. , Moving toward the technological applications, polariton parametric scattering has been applied to design advanced spectroscopic techniques, electro-optic switches, polariton amplifiers, and traps for polariton condensates . However, such phenomena and applications still demand cryogenic temperatures due to the small exciton binding energies of traditional semiconductor microcavities.…”