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

TL;DR

This paper proposes a method for topological quantum computing over noisy networks with high error rates, enabling error correction even with relatively noisy components, thus advancing scalable quantum computing.

Contribution

It introduces a protocol allowing error-prone quantum cells to perform purification and stabilize topologically encoded data, tolerating network errors above 10%.

Findings

Protocol succeeds with intra-cell error rates below 0.82%.

Achievable fidelity levels are within current laboratory capabilities.

Enables scalable quantum computing with highly noisy networks.

Abstract

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.