A bird's-eye view of quantum error correction and fault tolerance
arthurpesah.meQuantum error correction is a key ingredient for future realizations of fault-tolerant quantum computers.
Physics is local, so errors in far separated regions of the device are only slightly correlated. In this setting, threshold theorems can be proved to show that as long as the device is below some constant amount of noise at the physical level, the noise can be suppressed arbitrarily (exponentially) at the logical level.
Very interesting! How close are we to achieving said noise threshold?
More or less, we're just before the finish line. About 20% lower noise and we'll be there. For every little bit past that, the overhead gets reduced immensely