Key point: The mathematics that underpin quantum algorithms is well established, but there are daunting engineering challenges that remain.
Google announced this fall to much fanfare that it had demonstrated “quantum supremacy” – that is, it performed a specific quantum computation far faster than the best classical computers could achieve. IBM promptly critiqued the claim, saying that its own classical supercomputer could perform the computation at nearly the same speed with far greater fidelity and, therefore, the Google announcement should be taken “with a large dose of skepticism.”
This wasn’t the first time someone cast doubt on quantum computing. Last year, Michel Dyakonov, a theoretical physicist at the University of Montpellier in France, offered a slew of technical reasons why practical quantum supercomputers will never be built in an article in IEEE Spectrum, the flagship journal of electrical and computer engineering.
So how can you make sense of what is going on?
What’s a quantum computer?
To understand why, you need to understand how quantum computers work since they’re fundamentally different from classical computers.
A classical computer uses 0s and 1s to store data. These numbers could be voltages on different points in a circuit. But a quantum computer works on quantum bits, also known as qubits. You can picture them as waves that are associated with amplitude and phase.