ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT wigner.mta.hu>]

Kedves Érdeklődők!

A Szilárdtestfizikai Bizottság ülése miatt H. Obuse előadását új időpontra,
14:00, tettük.

Időpont: 2013. szeptember 03. (kedd) 14:00
Hely: MTA Wigner FK SZFI, I. épület 1. emeleti Tanácsterem



                              SZFI Kollokvium

OBUSE HIDEAKI (Department of Applied Physics, Hokkaido University, Japan,
vendéglátó: Asbóth János):
"Network model for 2D and 3D Z_2 topological insulators and its relation to
quantum walks"

Abstract:

In this seminar, I propose an efficient theoretical model, so-called
network model, describing the time-reversal Z_2 topological insulators in
two and three dimensions. The network model is defined on a network built
up from links and nodes and each node contains two input links of Kramers
pairs and two output links and is described by scattering matrices. Since
symmetry of the system is easily tuned through the scattering matrices and
geometry of input and output links, the network model is useful to study
topological insulators/superconductors which heavily depend on symmetry.

To begin with, I explain the network model for the two-dimensional
time-reversal Z_2 topological insulator (quantum spin Hall insulator), then
extend the model to the three-dimensional weak Z_2 topological insulator.
By using these network models, we study the Anderson transition of the
topological insulators with strong disorder. We find that the universality
class of the Anderson transition for these topological insulators are
identical to those of the ordinary symplectic class.

In the seminar, I also explain the relation between the network model and
the discreet-time quantum walk which is an emergent experimental setup to
investigate various topological phases.
Minden érdeklődőt szívesen látunk!