Observation of inversion, hysteresis, and collapse of spin in optically trapped polariton condensates

Abstract

The spin and intensity of optically trapped polariton condensates are studied under steady-state elliptically polarized nonresonant pumping. Three distinct effects are observed: (1) spin inversion where condensation occurs in the opposite handedness from the pump, (2) spin and intensity hysteresis as the pump power is scanned, and (3) a sharp "spin collapse" transition in the condensate spin as a function of the pump ellipticity. We show these effects are strongly dependent on trap size and sample position and are linked to small counterintuitive energy differences between the condensate spin components. Our results, which fail to be fully described within the commonly used nonlinear equations for polariton condensates, show that a more accurate microscopic picture is needed to unify these phenomena in a two-dimensional condensate theory.

All-Optical Linear-Polarization Engineering in Single and Coupled Exciton-Polariton Condensates

“…The strong nonlinear nature of polaritons through their spin-anisotropic excitonic Coulomb interactions results in numerous intriguing spinor condensate properties desirable in future spinoptronic technologies 3,4 . This includes spin bistability [5][6][7] and multistability 8 , switches 9,10 , optical spin Hall effect 11 , polarized solitons 12,13 and vortices [14][15][16] , spin bifurcation points 17 , and topological phases 18,19 . Different parts for polariton based spin circuitry have already been realized 9,10,[20][21][22] with some recent exciting theoretical proposals 23,24 , but many challenges remain to be solved.…”

Optical orientation, polarization pinning, and depolarization dynamics in optically confined polariton condensates

“…Because of their two-level spin structure, polaritons offer an exotic platform to study various non-Hermitian spin physics. Their sensitivity to external magnetic fields [6,7], cavity mirror birefringence [8], along with a unique spin-orbit coupling mechanism known as the optical spin Hall effect [9,10] has paved the way for the realization of polaritonic Chern insulators [11][12][13], polarized solitons [14] and half skyrmions [15], spin switches [16][17][18], spontaneous lattice ordered polarization [19], spinselective filters [20], spin bistability [21,22], spin multistabilty [23], spin valves [24], and measuring the quantum geometric tensor [25].…”

“…Nonlinearity is the needed ingredient for a device to perform nontrivial tasks [16,18], but it can also destabilize the spin state of the condensate, affecting said device performance. Recent studies have mapped out interesting condensate regimes of polarization buildup, collapse, inversion, and hysteresis [22], as well as deterministic control of linearly polarized emission [33], but with most of the work focused on few selected polarization components. Therefore, a full characterization of the emission properties of optically confined polariton condensates, and its stability properties, is still lacking.…”

Polariton spin jets through optical control

“…In semiconductor microcavities, exciton-polaritons (hereafter polaritons) are characterized by high temperature condensation [5,6], strong nonlinearity, ultrafast spin dynamics [7], and a multitude of optical-based techniques to manipulate their spin state. They offer a promising platform to investigate spin dynamics in extreme condensed matter settings [8][9][10][11][12][13][14][15], and for spinoptronic applications [16][17][18][19][20][21][22].…”