# Delocalisation and topological phases in disordered quantum walks

## Tibor Rakovszky

### (Eötvös Loránd University (Physics MSc student))

Time: Thu Dec 11 13:00:00 2014

Location: Building 1, Auditorium

In general 1 and 2 dimensional systems, the presence of disorder induces Anderson localisation. Eigenstates become localised to a finite region and as a consequence, transmission through the system decays exponentially with the system length. In 2011 Obuse & Kawakami showed, that a simple one dimensional quantum walk does not exhibit the signs of Anderson localisation. Instead, the walker spreads through the system in a subdiffusive way. In this talk, we examine this behaviour for a more general quantum walk protocol. Here, delocalisation appears only in the strongly disordered case. We will show, that this behaviour is a consequence of a topological phase transition.