Topological quantum computing with a very noisy network and local error rates approaching one percent

A scalable quantum computer could be built by networking together many simple processor cells, thus avoiding the need to create a single complex structure. The difficulty is that realistic quantum links are very error prone. A solution is for cells to repeatedly communicate with each other and so purify any imperfections; however prior studies suggest that the cells themselves must then have prohibitively low internal error rates. Here we describe a method by which even error-prone cells can perform purification: groups of cells generate shared resource states, which then enable stabilization of topologically encoded data. Given a realistically noisy network (≥10% error rate) we find that our protocol can succeed provided that intra-cell error rates for initialisation, state manipulation and measurement are below 0.82%. This level of fidelity is already achievable in several laboratory systems. One approach to build a scalable quantum computer is to connect many smaller cells into a larger whole, but for realistic systems this quickly becomes prone to errors. Nickerson et al. present a noisy network protocol that can withstand high error rates within each cell but still perform stable purification.