Quantum Computing, Fault Tolerance, Error Correction, Logical Qubits.
qubit that can be used effectively in a surface code takes of order 10³ to 10⁴ physical qubits.” “We find that nq increases rapidly as p approaches the threshold pth, so that a good target for the gate fidelity is above about 99.9% (p <~ 1/10³). In this case, a logical qubit will need to contain