Coherent phenomena in exciton–polariton systems

Exciton-polariton systems, formed through the strong coupling of excitons and photons, provide a unique platform for investigating quantum coherence and collective dynamics in solid-state systems. These hybrid quasiparticles combine photonic and excitonic characteristics, enabling phenomena such as Rabi oscillations, long-distance coherent energy transfer, ballistic energy transport, and Bose-Einstein condensation. Their ability to sustain macroscopic quantum coherence, alongside their sensitivity to environmental and system-engineering factors, highlights their potential for advancing both fundamental quantum science and practical applications, including nanophotonics, energy harvesting, and quantum technologies. This review aims to offer a comprehensive exploration of coherent phenomena in exciton-polariton systems, spanning theoretical foundations, experimental realizations, and applications. Key topics include the dynamics of strong light-matter coupling, the role of vibrational modes and energetic disorder, and the interplay between coherence and dissipation. Advances in ultrafast spectroscopy and quantum electrodynamics models have been pivotal in uncovering polaritonic behavior and optimizing system performance. Despite significant progress, challenges remain in maintaining coherence and addressing the effects of dissipation and disorder. By overcoming these hurdles, exciton-polariton systems promise transformative technological applications and deeper insights into quantum phenomena, positioning them as a cornerstone in the future of quantum science and technology.