Has Google really reached quantum supremacy? Yes and no...

For over a month, the tech community — and the world — has been buzzing with rumours that Google may have cracked quantum supremacy. On 23 October, Nature finally published the paper that proved those claims to be true. Or did it?

According to the paper, Google researchers created a task so big, it would take a state-of-the-art super computer with one million cores, 10,000 years to complete. Yet Google’s quantum processor, Sycamore, with its 53 working qubits, took 200 seconds.

But IBM isn’t ready to accept Google’s claim just yet. While IBM considers the feat “an excellent demonstration of the progress in superconducting-based quantum computing”, the company does not believe it constitutes ‘quantum supremacy’. For one, IBM considers quantum supremacy something that classical computers can’t do at all.

Second, IBM argues that, in a worst-case scenario, “an ideal simulation of the same task can be performed on a classical system in 2.5 days” with greater fidelity than that proposed by Google.

This is because IBM believes that, while Google considered parallels between the computers, fast and error-free computation and large aggregate RAM, they “failed to fully account for plentiful disk storage”. In contrast, IBM’s simulation incorporates both RAM and hard disk space, among other performance-enhancing techniques.

While the task isn’t particularly useful in either case, Google claims it serves as a proof-of-concept, with CEO Sundar Pichai comparing the feat to “the first rocket that successfully left Earth’s gravity to touch the edge of space”. Where rockets eventually took people to the moon and could one day take them to Mars and beyond, quantum computing could be used to design more efficient batteries and determine which molecules might become effective medicines.

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