Polarized light bursts from kicked quantum rings

Nonequilibrium quantum rings emit circular-polarized subterahertz radiation with a polarization degree controllable on nano- to picosecond time scales. This we conclude using a theory developed here for the time-dependent detection of the circular polarization of polychromatic radiations, valid for time scales comparable to the reciprocal of characteristic emission frequencies. The theory is applied to driven quantum rings whereby the influence of radiative and nonradiative processes on the properties of the emitted light is incorporated.