Quantization scheme of surface plasma polariton in helical liquid and the exchanging interaction between quasi particles and emitters

The collective modes of helical electron gases interacting with light have been studied in an extended random phase approximation. By separating two kinds of electron density oscillations, the complicate operator dynamics coupling electrons and photons can be simplified and solved. The inverse operator transformation that interprets electron oscillations and photons with quasi particles has been developed to study the interaction between surface plasma polaritons (SPPs) and emitters. Besides the ordinary interaction induced by electric field, we find an additional term which plays important roles at small distance arising from electron exchanging effect.