Accession Number : ADA313791

Title :   Theoretical Study of Quantum Systems Interacting with a Phonon Bath.

Descriptive Note : Final rept. 1 Aug 92-28 Feb 96,

Corporate Author : ILLINOIS UNIV AT CHICAGO CIRCLE DEPT OF PHYSICS

Personal Author(s) : Poetz, Walter

PDF Url : ADA313791

Report Date : 22 AUG 1996

Pagination or Media Count : 10

Abstract : We have developed two complimentary theoretical approaches to study the dynamics of coupled electron-phonon systems. The first is based on coherent-state functional representations of ensemble averages and has been shown useful in the strong coupling limit of the electron-phonon coupling. A new exactly solvable model has been identified. A two level system coupled to phonons has been used to demonstrate irreversible dynamics. The second approach is based on non-equilibrium Green's functions which were used to derive Boltzmann-Bloch equations useful in the weak coupling limit. It has been used to discuss screening in such systems and to gain microscopic understanding of phase breaking in semiconductor systems. Specifically, the damping of charge oscillations and THz pulse emission has been studied for GaAs-AlGaAs double wells. Scattering theory has been developed for open mesoscopic electronic devices, formally exact in one dimension and heuristically for higher dimension. The signature of Bloch oscillations in the I-V characteristics of p-i-n diodes has been investigated. Exact open boundary conditions have been developed for the one-dimensional time-dependent Schrodinger equation and applied to a study of the dynamics of multi-barrier semiconductor heterostructures.

Descriptors :   *QUANTUM WELLS, *PIN DIODES, COUPLING(INTERACTION), SCATTERING, PHONONS, GREENS FUNCTIONS, OSCILLATION, SCHRODINGER EQUATION, BOLTZMANN EQUATION, IRREVERSIBLE PROCESSES.

Subject Categories : Atomic and Molecular Physics and Spectroscopy
      Quantum Theory and Relativity

Distribution Statement : APPROVED FOR PUBLIC RELEASE