Xiaoyang Zhu1
Columbia University1
Spin-orbit coupling (SOC) of electrons is responsible for a number of quantum phenomena in solids, including spin Hall effect and topological insulators. Such SOC phenomena also emerge in photonic systems. In planar microcavities, the natural splitting between transverse electric (TE) and transverse magnetic (TM) modes behaves as a winding in-plane magnetic field B<sub>T</sub> on the photon spin and results in the photonic spin-Hall effect. If in-plane optical anisotropy is present to break rotational symmetry, there is an effectively constant magnetic field B<sub>XY</sub> which, in combination with B<sub>T</sub>, leads to a non-Abelian gauge field for photons or exciton-polaritons. While such photonic systems have been demonstrated for synthetic Rashba-Dresselhaus Hamiltonians, an exciting prospect is forming exciton-polariton condensates under such a gauge field to simulate a number of phenomena in SOC quantum fluids, in analogy to what have been demonstrated in SOC Bose-Einstein condensates (BECs) in cold atoms. Here we demonstrate SOC exciton-polariton condensation in microcavities composed of single crystal lead halide perovskites (LHPs) known for strong light-matter coupling. We take advantage of low-symmetry phases of LHPs with strong optical anisotropy, which is tunable by composition and/or temperature, and measure the spin textures produced by the effective magnetic fields using polarization resolved Fourier space photoluminescence (FS-PL) imaging. In the region near where B<sub>T </sub>and B<sub>XY</sub> cancel each other, the results are well-described by the Rashba-Dresselhaus Hamiltonian. As the SOC exciton-polaritons undergo condensation with increasing density, as is evidenced by a two-threshold lasing behavior, B<sub>T </sub>vanishes towards <i>k<sub>||</sub></i> = 0 and the dominance of B<sub>XY</sub> gives rise to two competing condensates with mutually orthogonal polarizations that are separated in space and momentum. These exciton-polariton condensates offer a platform for the exploration of many-body SOC phenomena in quantum fluids.