Probing the collective excitations of a spinor polariton fluid

TL;DR

This paper introduces a pump-probe method to analyze the collective excitations of a spinor polariton fluid, classifying spectra and polarization properties using tunable parameters, and explores spin dynamics and instabilities.

Contribution

It provides a comprehensive classification of excitation spectra and polarization in spinor polariton fluids based on a linear response approach with tunable parameters.

Findings

Transmitted light can undergo spin rotation along the dispersion.

Spin flip is enhanced near parametric amplification instability.

Spectra are classified as diffusive-like with specific polarization properties.

Abstract

We propose a pump-probe set-up to analyse the properties of the collective excitation spectrum of a spinor polariton fluid. By using a linear response approximation scheme, we carry on a complete classification of all excitation spectra, as well as their intrinsic degree of polarisation, in terms of two experimentally tunable parameters only, the mean-field polarisation angle and a rescaled pump detuning. We evaluate the system response to the external probe, and show that the transmitted light can undergo a spin rotation along the dispersion for spectra that we classify as diffusive-like. We show that in this case, the spin flip predicted along the dispersion is enhanced when the system is close to a parametrically amplified instability.