[arksingrad]

> The second scheme, on the right ... Calculations must be discarded rather than corrected when problems are found.

I understand the title is technically correct, and the field of quantum error correction (and error correction in general) encompasses the detection of errors as well as the correction of them. However error detection and error correction are different (but highly related!) problems, and there are are a variety of codes that are good at each. They tried out one error correcting code, and one error detecting (in this instance) code.

It's very cool to see the surface code put to use, and I've always found it intriguing how quantum computer design is motivated by the topology of the underlying error correcting codes. There's a similar proposal for ion-trapped quantum computing where you use a 2D array of trapped ions, rather than a single linear chain, to represent your qubits. You then use different atomic ions for your logical vs error correcting qubits, and you need some different fundamental operations than you do for interactions with a linear chain of ions.