## Algebra and Combinatorics Seminar

**Date:** November 17, 2017

**Time:** 3:00PM - 4:00PM

**Location:** BLOC 117

**Speaker:** X. Shawn Cui, Stanford University

**Title:** *Topological quantum computation and compilation*

**Abstract:** Topological quantum computation is a fault tolerant protocol for quantum computing using non-abelian topological phases of matter. Information is encoded in states of multi-quasiparticle excitations(anyons), and quantum gates are realized by braiding of anyons. The mathematical foundation of anyon systems is described by unitary modular tensor categories. We will show one can encode a qutrit in four anyons in the SU(2)_4 anyon system, and universal qutrit computation is achieved by braiding of anyons and one projective measurement which checks whether the total charge of two anyons is trivial. We will also give an algorithm to approximate an arbitrary quantum gate with the ones from the anyon system. The algorithm produces more efficient circuits than the Solovay-Kitaev algorithm. Time allowed, applications in quantum complexity classes will also be addressed.