In the quote, "few hundred qubits", qubits are logical qubits. Google's 72-qubits are physical qubits. You implement error correction on the physical qubits, af

In the quote, "few hundred qubits", qubits are logical qubits. Google's 72-qubits are physical qubits. You implement error correction on the physical qubits, after which you are left with a lot fewer logical qubits, to do your actual computation with. > Does the power of a quantum computer scale linearly with number of qubits? It scales linearly with the number of logical qubits, in the same sense the power of a turing machine scales linearly with the size of the tape. Also, for a realistic system of hundreds of qubits, you will need tens of thousands of physical qubits. > Does the difficulty in manufacturing scale linearly with number of qubits? If you want the ability to do entangling operations on any two qubits, however far apart they are physically, the manufacturing difficulty scales quadratically with the number of qubits at least. However, you can choose to only have the ability to do entangling operations on near by qubits, and use swap operations to move the state of the qubits around. This will reduce manufacturing difficulty scaling, but will increase the time of any computation you perform.