The non-commutative topological approach to topological phases with protecting symmetry

Abstract: In this talk we review the K-theoretic description of topological phases of insulators and superconductors in the effective one particle approximation. In that approximation, an insulator (or superconductor) is described by a Hamiltonian whose spectrum has a gap at the Fermi energy. Two Hamiltonians belong to the same topological phase if they can be deformed into each other without closing the gap. For this to be well-defined, it is important to specify the space of possible Hamiltonians with its topology. When this space is taken to be a C*-algebra equipped with a real structure and a grading, one can use real graded K-theory and its dual (K-homology or cyclic cohomology) to describe the topological phases and their numerical topological invariants.

high energy physicsMathematics

Audience: researchers in the topic

Darboux Seminar

Series comments: Schedule available on www.phys.ens.fr/~kashani/Darboux_list.html