Recently, the team of Dong Hongxing and Zhang Long, researchers of the Infrared Optical Materials Research Center of the Advanced Laser and Optoelectronic Functional Materials Department of the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, together with the scientific researchers of East China Normal University, analyzed the dynamic process and physical mechanism of the phase transition from superfluorescence to the coaexciton polariton condensation based on the perovskite quantum dot film system. The related research results are titled "Observation of Transition from Superfluorescence to Polarization Condensation in CsPbBr3 Quantum Dots Film" and published in "Light Science&Applications".

Superfluorescence is an ideal platform for studying the multi body related mechanisms in exciton systems and developing bright quantum light sources and ultrafast optical technologies. At the same time, synergistic excitons have the characteristic of higher oscillator strength, which is conducive to conducting research on the nonlinear properties of synergistic excitons, making it easier to achieve polariton condensation of synergistic excitons, and helping to achieve applications in fields such as quantum logic gates and topological state lasing. At present, there are few studies on the regulation of the coupling strength between light and cooperative matter states, as well as the phase transition mechanism from superfluorescence to synergistic exciton polariton condensation. It is crucial for the further development and application of quantum devices to achieve coupling strength tuning between light and cooperative matter states based on quantum dot systems, and to analyze the ultrafast phase transition controlled by cavity optical fields.

This study proposes the introduction of an external cavity to tune the coupling strength between light and synergistic excitons. Based on the perovskite quantum dot thin film structure on the half cavity of a distributed Bragg reflector, the strong coupling phenomenon between synergistic excitons and Bragg modes is demonstrated, and the Rabi splitting is 21.6 meV. Furthermore, this study observed the phenomenon of synergistic exciton polarization polariton condensation. The study found that the involved excitons exhibited significant coupling enhancement. This is mainly due to the synergistic effect inducing random phase synchronization of excitons, resulting in the formation of macroscopic dipole moments with consistent polarization directions. The new quasi particle Bose Einstein condensation provides new possibilities for the development of ultra narrow tunable lasers. In addition, the dual light matter properties of co exciton polariton condensation have expanded its potential applications in quantum simulation, non-traditional coherent light sources, and all optical polarization logic devices.

The research work has received support from the National Natural Science Foundation of China, the Shanghai Youth Top Talent Program, and the Shanghai Leading Talent Training Program.

Paper link：：论文链接