Nature 482, 489–494 (2012)

Error correction enables computing machines constructed from fault-prone components to perform calculations with arbitrary precision. This works also, at least in principle, for quantum computers, and several codes for quantum error correction have been devised over the years.

For most of these codes, however, the demands on hardware are dauntingly, if not prohibitively, high. Therefore, the experiment performed by Xing-Can Yao and colleagues is particularly welcome: they have implemented an approach that works at relatively modest error rates and requires only nearest-neighbour interactions between particles, which makes application more feasible.

The method, known as topological error correction, exploits the topology of so-called cluster states. Yao et al. inscribe such a cluster state on eight photons. When one of the qubits is disturbed, the faulty 'component' can be located and the error corrected. And when the error affects all qubits simultaneously, the effective error rate can also be lowered, underlining the promise of the approach.