Past exam of the mathematics course of the University of Cambridge 2023 iii Paper 342 1 b Solution 2026-09-28
Since , direct multiplication gives the matrix inverseprovided , as required by invertibility of the K-matrix. For ,The attached gauge-flux vector is thereforeRelative to the electron in part a, every one of the gauge fields consequently carries the additional flux
Past exam of the mathematics course of the University of Cambridge 2024 iii Paper 342 1 d Solution 2026-09-28
Forthe vectors and haveThe K-matrix formula therefore gives bosonic self-exchange for and mutual full-braiding phaseFusion adds vectors. Becauseboth double fusions lie in and braid trivially with every vector; hence they represent the vacuum in the anyon lattice of an Abelian Chern--Simons theory. Finally has , so its exchange phase is . These are exactly the fusion and braiding data of the surface-code anyon model.