📝 SummarXiv

Abstract

We introduce a new framework for achieving universal topological quantum computation using Ising anyons via braiding alone. Our approach builds on recent developments in non-semisimple topological quantum field theories in (2+1)-dimensions, which extend the traditional semisimple paradigm. While standard Ising anyons are limited to Clifford operations and thus not computationally universal, we show that their non-semisimple counterparts give rise to new anyon types we call \emph{neglectons}; adding a single neglecton to the traditional Ising theory enables universal quantum computation through braiding alone. The resulting braid group representations are unitary with respect to an indefinite Hermitian form, with the computational subspace embedded in a positive-definite sector. We identify a range of parameters for which the model supports universal gate sets and, notably, special values of the parameter $\alpha$ where the computational subspace decouples exactly from the negative-norm components of the Hilbert space. This leads to low-leakage, fully unitary evolution on the physical subspace and improved prospects for efficient gate compilation.