Nice article, but not really a quantum computer or even a system that needs quantum mechanics to explain it. You could do the same calculation with an analog system (e.g. a capacitor that you add/remove charges to/from). The argument from Scott Aaronson about quantum advantage that the author refers to is really not very relevant, as a single qubit doesn't have any information encoding advantage over an analog system. A quantum computer simply cannot produce a speed advantage without relying on entanglement at some point during the quantum computation. So: no entanglement = no speed advantage.