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Lamb shift for an excitonic molecule
Author(s) -
Ivanov A. L.,
Haug H.
Publication year - 1995
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221880106
Subject(s) - polariton , physics , exciton , renormalization , condensed matter physics , resonance (particle physics) , momentum (technical analysis) , dispersion (optics) , dispersion relation , photon , quantum mechanics , atomic physics , quantum electrodynamics , finance , economics
A theory of the optical decay and of the resonant two‐photon creation of an excitonic molecule (xx) in direct band gap semiconductors is given within the polariton picture. An xx Schrödinger equation which includes both the Coulombic exciton‐exciton attraction and the polariton coupling is derived and analyzed. The solution of this equation describes an xx as the quasibound two‐polariton complex. The real and imaginary parts of the xx energy give self‐consistently the inverse xx radiative lifetime Γ xx and the radiative renormalization Δ xx of the xx energy (the xx Lamb shift), respectively. For 3D (CuCl) the polariton effects result in a non‐parabolic xx dispersion with M xx eff→ ∞ at zero momentum; for quasi‐2D (GaAs) they lead to a “Mexican hat” structure in the xx dispersion at small momenta together with a considerable increase of both the xx effective binding energy ϵ xx and lifetime Γ xx . For quasi‐ID the influence of the polariton effects is so strong that an xx can exist only as a broad resonance (ϵ xx ∼ Γ xx ).