Braiding defects in topological stabiliser codes of any dimension cannot be universal

Abstract

Braiding defects in topological stabiliser codes has been widely studied as a promising approach to fault-tolerant quantum computing. We present a no-go theorem that places very strong limitations on the potential of such schemes for universal fault-tolerant quantum computing in any spatial dimension. In particular, we show that, for the natural encoding of quantum information in defects in topological stabiliser codes, the set of logical operators implementable by braiding defects is contained in the Clifford group. Indeed, we show that this remains true even when supplemented with locality-preserving logical operators.

6 pages; results from this preprint are now fully contained in the longer manuscript arXiv:1906.01045 (published as Phys. Rev. A 102, 022403 (2020))