Abstract: 

Quantum walks were first defined as a quantum analogue of random walks and can also be used to model the discrete time evolution of a quantum mechanical Hamiltonian. In this talk, I will introduce an algebraic framework to compute the essential spectrum of quantum walk unitaries. Time permitting, I will also give some remarks about why scattering theory methods may also be of relevance to quantum walk systems.

This is partially based on work-in-progress with S. Richard and Y. Tanaka.