Fault-tolerant quantum computer
결함 허용 양자컴퓨터
A quantum computer that keeps fixing its own errors as it goes, so it can finish a long calculation.
Overview
Today's quantum computers pile up errors as a calculation gets longer, and the answer ends up a mess. A fault-tolerant quantum computer keeps finding and fixing mistakes during the calculation, so errors get fixed faster than they build up. Then even a very long calculation can be run to the end with confidence.
To get there, the errors of physical qubits must drop below a certain level, and there must be enough qubits to make many logical qubits. Most of the things people hope for, such as breaking codes or calculating molecules for new drugs, become possible only at this stage. We are still on the way there.
An everyday example
If a spell checker fixed every mistake right away as you wrote, you could finish even a very long text without a typo. The fixing has to be faster than the mistakes.
Why it matters
This term is always at the end of the roadmaps quantum companies publish. The question "when will quantum computers become useful" is really the question "when will we reach this stage."
Also calledFTQC, error-tolerant quantum computer