Q-Math Seminar
Superselection theory for stacked systems
Speaker: Pieter Naaijkens (U. Cardiff, UK)Date: Wednesday, 18 February 2026 - 11:00Place: Room 2.2.D08, Universidad Carlos III de Madrid
Online: https://meet.google.com/ksm-xzou-bgp (active on request)
Abstract:
In this talk I will introduce the theory of quantum superselection sectors from an algebraic perspective. We will then consider the DHR superselection sector theory for stacked topologically ordered systems. It is relatively easy to construct sectors of the stacked system from sectors of the individual layers. The question if all sectors of the stacked system are obtained in this way is more subtle. I will show that under physically reasonable conditions, this is the case and we can give a complete characterisation of the sector theory of the stacked system. I will then discuss some applications to invertible phases and the colour code. Based on joint work with Sven Bachmann, Alan Getz and Naomi Wray.
