Quantum computing firm IonQ has sold a device that it claims will be able to outperform any classical supercomputer or other quantum computer in the world – but the machine has yet to be built and experts are sceptical about its performance. So who currently claims the quantum crown?
Part of the problem is that comparing quantum computers made using a variety of technologies by different companies is far from an exact science. One measure is the number of qubits, or quantum bits, a computer has, with more …