Dynamics of Strongly Coupled Hybrid States by Transient Absorption Spectroscopy

Since the birth of quantum mechanics the construction and control of novel hybrid quantum states are among the dream targets of scientists. In this regard, due to recent technological advances, hybrid states based on strong coupling occurring between light and matter have become a laboratory reality. For example, it is demonstrated that strong coupling involving microcavities or surface plasmon polaritons shows great potential for novel nanoplasmonic devices such as lasers, all-optical switching, field-effect transistors, and for the evergreen field of quantum computation. Further developments in this field require, however, a better understanding of the underlying mechanisms governing strong coupling, especially from a time-dependent point of view, time-resolved spectroscopy being one of the leading experimental approaches to address this aspect. In this perspective, after a brief introduction of the strong coupling concept, the recent research progress on the dynamics of strongly coupled systems involving J-aggregates, broadly absorptive dyes, semiconductor quantum dots, and perovskite films with either microcavities or surface plasmons polaritons is summarized and discussed. Finally, challenges and perspectives for developing strong coupling concept are further illustrated, with special attention to phonon-photon interaction, as one of the most intriguing topics in condensed matter physics.