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On the Representation of the Non‐Stationary Density Matrix of an Electron–Phonon System by a Functional Integral
Author(s) -
Fomin V. M.,
Pokatilov E. P.
Publication year - 1978
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.2220870238
Subject(s) - electron , phonon , anisotropy , physics , density matrix , polarization (electrochemistry) , tensor (intrinsic definition) , condensed matter physics , matrix (chemical analysis) , quantum mechanics , materials science , chemistry , quantum , mathematics , geometry , composite material
A non‐stationary density matrix depending on the coordinates of both electron and phonons is obtained for an ensemble of electron–phonon systems with an arbitrary initial distribution. This density matrix is used to describe the non‐linear optical properties of a semiconductor in the presence of a flow of electrons. A generalized non‐linear dielectric permeability tensor and a generation tensor are found for this case. The anisotropy of absorption, the birefrigence, the transformation of type, and change of parameters of the laser wave polarization and the second harmonic generation due to the flow of electrons are discussed.