Potential gradient control of room-temperature triangular-whispering gallery polariton condensate*

Exciton polaritons offer hybrid nature of excitons and photons, which are interactive quasi-particles providing the potential energy manipulation. Although wide bandgap semiconductors form room-temperature polaritons, the fabrication of homogeneous planar microcavities is challenging due to low refractive index contrast and large lattice misfit in III-nitride systems. Consequently, lateral localization of planar cavities by disorder (potential fluctuation and dephasing) hinder the establishment of ballistic extensions of polariton condensates, an essential factor for any quantum controls. We introduce a room-temperature polariton system with low disorder capable of one-dimensional (1D) ballistic extension.¹ Selectively grown GaN wires reduce disorder in both excitons by dislocation bending and photons by crystallographically defined hexagonal facet. This high-quality wire allows us to form room-temperature triangular-whispering gallery polariton condensates with ballistic extension controlled by the optical potential gradient. The correlation between transport characteristics from momentum and real space offers a strong indication of ballistic transport in this 1D system.
1. H. G. Song et al, Optica 6, 1313 (2019)