# Quantum Impurity Entanglement

**Erik Sorenson**

McMaster University

Wednesday, February 7, 2007

10:30 AM @ Stirling 201

## Abstract:

A system that can be divided into two parts A and B is said to be entangled if the ground-state wavefunction cannot be written as a product $|A>|B>$. While entanglement is at the foundation of the fields of quantum information/computing it has recently been recognized as a crucial concept for understanding quantum critical phenomena, topological phases and efficient numerical methods as they are used in the field of condensed matter. In this talk I will try to describe some of these recent developments from the point of view of both theory and experiment. In particular, I will focus on entanglement in spin chains and describe recent work showing how impurities become entangled with the bulk spin chain. In some cases a simple intuitive picture can be developed allowing for almost exact variational calculations.

*Note: Room change!*