quantum error correction
Machines that find and repair their own errors while they run.
Quantum error correction spreads each piece of information across many physical qubits. The machine keeps checking for errors and repairs them during the program. This needs many more qubits than today's machines have, so it is still being developed. Machines that do it reliably are called fault-tolerant. They are the long-term goal of the field.
Think of it as
Like sending every important message three times, so the reader can spot and fix any copy that got garbled.
Example
A company asks a provider when its machine will be fault-tolerant. The answer depends on how many physical qubits each error-corrected qubit needs, and how fast the provider can build them.