Continuous and discontinuous dark solitons in polariton condensates

TL;DR

This paper analyzes dark solitons in polariton condensates, revealing continuous and discontinuous solutions, and compares them with Gross-Pitaevskii model predictions within their valid parameter regimes.

Contribution

It derives a single-mode Gross-Pitaevskii model from the two-equation Schrödinger system and explores the conditions leading to discontinuous exciton wavefunctions.

Findings

Dark soliton solutions form a frequency band with varying far-field values.

Discontinuities occur in exciton wavefunctions beyond the GP model's validity.

Comparison between polariton solitons and GP solitons highlights differences in their properties.

Abstract

Bose-Einstein condensates of exciton-polaritons are described by a Schr\"odinger system of two equations. Nonlinearity due to exciton interactions gives rise to a frequency band of dark soliton solutions, which are found analytically for the lossless zero-velocity case. The soliton's far-field value varies from zero to infinity as the operating frequency varies across the band. For positive detuning (photon frequency higher than exciton frequency), the exciton wavefunction becomes discontinuous when the operating frequency exceeds the exciton frequency. This phenomenon lies outside the parameter regime of validity of the Gross-Pitaevskii (GP) model. Within its regime of validity, we give a derivation of a single-mode GP model from the initial Schr\"odinger system and compare the continuous polariton solitons and GP solitons using the healing length notion.