#schor — Public Fediverse posts

The whole point to a #qubit is we don’t measure it until the end of the computation which, like Schrödinger’s cat, seals its fate.

So if you were to “read” a bunch of qubits to form a #checksum or a #CRC, you’d destroy their quantum nature in the process making your computer not very useful.

You can’t even copy a bit to use something like #triple #redundancy, either. There seems to be no way to practically duplicate a qubit.

#Peter #Schor came up with an answer. Instead of copying a qubit directly, the computer can spread a logical qubit across nine actual qubits. It is then possible to determine if there has been a single physical qubit error using a complicated algorithm.

Later research has dropped the number of qubits required down to five which appears to be the theoretical limit.

https://hackaday.com/2021/11/11/scientific-honesty-and-quantum-computings-latest-theoretical-hurdle/