Polariton-polariton interaction constants in microcavities

TLDR

Resonant transmission of light through a microcavity in the strong coupling regime is used to estimate the strength of polariton–polariton interactions for parallel and antiparallel spins, and the authors theoretically analyze mean‑field electrostatic, direct exchange, Van‑der‑Waals, and indirect exchange via dark exciton and biexciton states. The ratio α₂/α₁ is strongly dependent on detuning between exciton and photon modes, shifting from about 0 to less than –1 as detuning goes from negative to zero, and under certain conditions polaritons may condense in real space rather than form a Bose–Einstein condensate.

Abstract

Resonant transmission of light through a microcavity in the strong coupling regime is used to estimate the strength of the interaction between polaritons with parallel $({\ensuremath{\alpha}}_{1})$ or antiparallel $({\ensuremath{\alpha}}_{2})$ spins. The ratio ${\ensuremath{\alpha}}_{2}/{\ensuremath{\alpha}}_{1}$ is found to be strongly dependent on the detuning between exciton and photon modes. From negative to zero detuning it changes from about 0 to less than $\ensuremath{-}1$. Our observations indicate that at certain conditions the polaritons might rather condense in the real space than form a Bose-Einstein condensate. We analyze theoretically different mechanisms of polariton-polariton interaction including the mean-field electrostatic interaction, the direct exchange interaction, the Van-der-Waals interaction and the indirect exchange interaction via dark exciton and biexciton states.