Eksitonpolartoner

Eksitonpolartoner are quasiparticles formed when an exciton, a bound electron–hole pair in a semiconductor or organic material, strongly couples to a photon confined in a microcavity or waveguide. The hybrid light–matter nature grants a very light effective mass and substantial interactions, enabling rich collective phenomena at higher temperatures than purely photonic systems.

In the strong coupling regime, the coupled system yields two polariton branches: a lower polariton and an upper polariton. The energy gap between them is the Rabi splitting. The LP branch near zero in-plane momentum is extremely light, and the exciton/photon composition changes with detuning, described by Hopfield coefficients.

Because photons escape the cavity, exciton-polaritons have finite lifetimes and exist in non-equilibrium conditions. Their dynamics are often modeled with driven-dissipative equations. Interactions between polaritons and with phonons or disorder produce nonlinearities, polariton condensation, and spontaneous coherence. Experiments report Bose-Einstein condensation–like behavior, superfluid signatures, and low-threshold polariton lasing.

Platforms include inorganic semiconductor cavities such as GaAs and CdTe, organic semiconductors, perovskites, and atomically thin materials integrated into microcavities or waveguides. Various cavity geometries — planar, pillar, and open cavities — enable momentum-resolved spectroscopy and device architectures.

Applications under exploration include low-threshold polariton lasers, ultrafast switches, neuromorphic photonics, and quantum simulators for many-body physics.

Historically, strong coupling between excitons and photons was first demonstrated in semiconductor microcavities in the 1990s, with subsequent room-temperature demonstrations in organic and hybrid materials.