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Influence of a phonon bath on the hierarchy of electronic densities in an optically excited semiconductor

Title data

Axt, Vollrath M. ; Victor, K. ; Stahl, Arne:
Influence of a phonon bath on the hierarchy of electronic densities in an optically excited semiconductor.
In: Physical Review B. Vol. 53 (1996) Issue 11 . - pp. 7244-7258.
ISSN 0163-1829
DOI: https://doi.org/10.1103/PhysRevB.53.7244

Abstract in another language

The influence of a phonon bath on the dynamics of the many-body density matrices relevant for the nonlinear optical response of semiconductors is studied. It is shown that, as in the phonon-free case, only a finite set of electronic density matrices is needed to describe the optical response in a χ(n) experiment. However, to obtain a closed set of equations of motion on the χ(n) level additional truncation concepts have to be introduced in order to decouple the infinite hierarchy of phonon-assisted density matrices. Relations characteristic of intrinsic systems, that have previously been derived to reduce the number of independent dynamical variables in the phonon-free case, are generalized. While in a coherent system the optical response is completely determined by transition-type variables, under the influence of a phonon bath occupation densities can also become independent dynamical quantities. Numerical results for a simple one-dimensional model are presented. Memory effects and dephasing induced by the electron-phonon coupling are discussed for all χ(3) relevant electronic density matrices. The pump-probe signal for σ+-σ− excitation in the spectral region of the biexciton is analyzed. The respective contributions of two processes for the generation of biexcitons, via two- photon transitions (TPT’s) or from previously generated exciton densities, to the microscopic dynamics are identified. The second process yields a χ(3) signal only due to the coupling to the phonon bath and turns out to contribute considerably less than the TPT under all conditions studied in this paper.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Excitons; Biexcitons; phonons; density matrix theory; dynamics controlled truncation; semiconductor dynamics; non-linear optics; ultrafast dynamics
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III > Chair Theoretical Physics III - Univ.-Prof. Dr. Martin Axt
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III
Result of work at the UBT: No
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 16 Oct 2017 10:04
Last Modified: 16 Oct 2017 10:04
URI: https://eref.uni-bayreuth.de/id/eprint/40012