Intersubband polariton-polariton scattering in a dispersive microcavity

TL;DR

This study investigates the ultrafast dynamics of intersubband polaritons in dispersive microcavities, revealing stimulated polariton-polariton scattering and advancing prospects for quantum control and lasing in mid-infrared systems.

Contribution

It provides the first direct experimental observation and quantum mechanical modeling of stimulated polariton-polariton scattering in dispersive microcavities.

Findings

Observation of a narrowband maximum at $k_{||}=0$ in reflectivity.

Identification of stimulated coherent polariton-polariton scattering.

Advancement towards quantum control and bosonic lasing in mid-infrared polaritonic systems.

Abstract

The ultrafast scattering dynamics of intersubband polaritons in dispersive cavities embedding GaAs/AlGaAs quantum wells are studied directly within their band structure using a non-collinear pump-probe geometry with phase-stable mid-infrared pulses. Selective excitation of the lower polariton at a frequency of ~25 THz and at a finite in-plane momentum, $k_{||}$, leads to the emergence of a narrowband maximum in the probe reflectivity at $k_{||}=0$. A quantum mechanical model identifies the underlying microscopic process as stimulated coherent polariton-polariton scattering. These results mark an important milestone towards quantum control and bosonic lasing in custom-tailored polaritonic systems in the mid and far-infrared.