The future of quantum computing

As far as we know, we’ll never trade in all our classical computers for quantum computing models. Quantum computers aren’t good for performing the mundane tasks that we assign to most computers today. You wouldn’t want to program a simple spreadsheet on a quantum computer, even if you could find a way to do it.

But to solve certain kinds of problems, a quantum computer with sufficiently many qubits will leave classical computers in the dust. Chapter 9 shows you how sufficiently powerful quantum computers will be able to factor 2,048-bit numbers. According to some estimates, a factoring problem that would take classical computers 300 trillion years to solve will require only 10 seconds of a quantum computer’s time. If we can achieve an advantage of this kind using a real quantum computer, we call it quantum supremacy.

In 2019, a team at Google claimed to have demonstrated quantum supremacy. Its 53-qubit quantum computer...