If a small quantum computer makes a small number of errors, will a larger one make many more errors, rendering it completely useless? Not so, say Google researchers, who have made important progress in correcting errors in quantum devices, paving the way for a theoretical path to creating useful, practical machines.
Ordinary computers store data as bits of 0 or 1, but errors can cause bits to “flip” to the wrong value, so devices from smartphones to supercomputers have built-in error correction.