Even spheres as joint spectra of matrix models

Abstract

The Clifford spectrum is a form of joint spectrum for noncommuting matrices. This theory has been applied in photonics, condensed matter and string theory. In applications, the Clifford spectrum can be efficiently approximated using numerical methods, but this only is possible in low dimensional example. Here we examine the higher-dimensional spheres that can arise from theoretical examples. We also describe a constuctive method to generate five real symmetric almost commuting matrices that have a $K$-theoretical obstruction to being close to commuting matrices. For this, we look to matrix models of topological electric circuits.