The final public oral examination of Emil Yuzbashyan will take place on Thursday, August 19, 2004 at 12:00 p.m. in Room 202. The examining committee will consist of Professors B. Altshuler, A. Polyakov, A. Bazarko and S. Sondhi. Any other members of the University wishing to attend the examination may do so.

The thesis of Emil Yuzbashyan, entitled From BCS Theory to Electron Spin Dynamics in Semiconductor Quantum Dots, has been placed on deposit on July 29, 2004.

Any member of the University wishing to read the thesis may do so. Any objections should be submitted to me in writing. The principal advisor for this work was Professor Boris Altshuler.

ABSTRACT

We study a number of strongly correlated many-body quantum systems. Most of the thesis is devoted to effects of pairing between fermions. In particular, we develop an explicit description of a time-dependent response of fermionic condensates to external perturbations. The dynamics of Cooper pairs at times shorter than the energy relaxation time can be described by the BCS model. We obtain a general explicit solution for the dynamics of the BCS model. We also solve a closely related dynamical problem - the central spin model, which describes a localized spin coupled to a `spin bath'. This model has a range of interesting applications, in particular to the issue of electron spin coherence in semiconductor quantum dots. We evaluate finite size corrections for the BCS model, which is relevant for small systems such as metallic grains. In the reminder of the thesis, we study the connection between symmetry and degeneracy in quantum systems. We propose a method for extracting hidden symmetry from the energy spectrum and clarify the origin of crossings and degeneracies in the 1d Hubbard model.

Daniel Marlow
Chair, Dept. of Physics