IngentaConnect S -Matrix Theory of Ultrafast Optical Phenomena in Semiconductors

Author: Kuznetsov A.V.

Source: Annals of Physics, Volume 258, Number 2, August 1997 , pp. 157-209(53)

Abstract:

A formalism for describing optical and transport properties of semiconductors excited by ultrashort laser pulses is presented. In contrast to existing theories, the quantum dynamics is described in terms of appropriately generalized single-particle wavefunctions ( S -matrix) instead of the ensemble-averaged observables such as distribution functions. The S -matrix is an operator that relates Heisenberg second quantization operators at finite times to their values in a vacuum state prior to excitation. The explicit form of the S -matrix is given by a perturbative expansion whose terms contain pairs of creation and annihilation operators. The coefficients of the expansion are found using a specially developed diagram technique for Coulomb systems. The first ( c -number) term of this expansion is formed from single-electron wavefunctions in an optically excited noninteracting system. In real space, these wavefunctions are well-defined wavepackets whose properties can be investigated analytically. Linear and nonlinear ultrafast optical phenomena are controlled by overlap between conduction and valence band wavepackets. Specific cases of noninteracting electrons, coherent interactions leading to excitonic effects, and the incoherent scattering in the Born approximation are analysed within the S -matrix approach.

Language: English

Document Type: Research article

Affiliations: Department of Physics, Ohio State University, 174 West 18 th Avenue, Columbus, Ohio, 43210:

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