Quantum Computing, Fault Tolerance, Error Correction, Logical Qubits.
5 = 3 * 25 minus 10 = 75 minus 10 = 65 total physical qubits per logical qubit. And I verified those numbers by counting the respective qubits in the diagram in Figure 6 of the IBM paper: Data = 5 * 5 = 25 Syndrome (dark) = 5 * 4 = 20 Flag (white) = 4 * 5 = 20 Total 25 + 20 + 20 = 65 total physical