University
of Toronto
Physics Department
Quantum Optics and Condensed Matter
THURSDAY SEMINAR
University
of Toronto
THURSDAY SEMINAR
| Speaker : | PROF. BRAD MARSTON
Department of Physics Brown University |
| Topic : | USING SUPERSYMMETRY AND THE DENSITY-MATRIX RG
TO UNDERSTAND DISORDER AND QUANTUM CRITICALITY |
| Time : | Thursday, November 11, 1999 at 11:00 a.m.
NOTE UNUSUAL TIME AND DATE |
| Place : | Room MP1115, Burton Tower 60 St. George Street / 255 Huron Street |
Abstract
The physics of localization transitions, and especially quantum critical
behavior at the transitions, is rich and nontrivial. Supersymmetry
(SUSY) is one of several methods that have been employed to carry out averages
over different realizations of quenched disorder. The resulting many-body
Hamiltonians can then be studied analytically and also numerically with
the use of the density-matrix renormalization-group (DMRG) technique.
Successes include exact proofs of non-vanishing density-of-states (DOS)
and quantum criticality at the plateau transition in the integer quantum
Hall effect (IQHE), and the accurate calculation of critical exponents
in the spin quantum Hall effect (SQHE). However, the calculation
of corresponding exponents for the IQHE transitions has proved to be much
more difficult. I discuss the reasons for this difficulty, and ongoing
work to circumvent the problem.
Local Host: Rashmi C. Desai 
(416-978-5191)