excitonfotonsystem

An exciton-photon system is a hybrid quantum system in which excitons—bound electron-hole pairs in a semiconductor or organic material—strongly couple to photons confined in a photonic structure, such as an optical microcavity, waveguide, or photonic crystal cavity. When the light-matter coupling strength exceeds the loss rates of both constituents, the system enters the strong coupling regime, and the bare exciton and photon states hybridize into new eigenstates known as exciton polaritons. The energy spectrum exhibits an anticrossing with a Rabi splitting that scales with the coupling strength, reflecting the mixed light and matter character of the modes.

Realizations span inorganic and organic platforms, including quantum wells embedded in distributed Bragg reflector cavities, organic semiconductors in microcavities, and atomically thin materials like transition metal dichalcogenides coupled to optical cavities. In waveguides and photonic crystals, guided photons can hybridize with excitons to form propagating polariton modes. The system is often described by Jaynes-Cummings-type or Tavis-Cummings models for one or several excitons coupled to photonic modes, yielding lower and upper polariton branches with modified dispersions and Hopfield coefficients that quantify their photon and exciton content.

Dynamics and phenomena include nonlinear polariton interactions and the possibility of nonequilibrium condensates or superfluid-like behavior at relatively high temperatures in suitable materials. Applications span polariton lasers with low thresholds, ultrafast optical switching, quantum simulators, and photonic devices for information processing, making exciton-photon systems a prominent platform for studying light-matter coupling and hybrid quantum phenomena.