### Quantum and classical localisation transitions

Chalker, J *(Oxford)*

Tuesday 19 August 2008, 10:00-11:00

Seminar Room 1, Newton Institute

#### Abstract

Localisation of a particle moving in a random environment may occur both quantum mechanically and with classical dynamics, but the phenomenon is very different in the two cases. I will discuss a class of quantum-mchanical localisation problems for which some physical quantities can be expressed exactly in terms of averages taken in a classical counterpart. The equivalence holds despite the fact that interference effects dominate the behaviour of the quantum systems. The models are network models belonging to class C in Zirnbauer's classification. The equivalence was first discovered in the context of the spin quantum Hall effect by Gruzberg, Ludwig and Read [Phys. Rev. Lett. 82, 4524 (1999)], and the results I will describe were obtained in collaboration with Beamond and Cardy [Phys Rev B 65, 214301 (2002) and with Ortuno and Somoza [in preparation].

#### Presentation

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