How Should Crypto Prepare for Google’s ‘Quantum Supremacy’?

“Quantum supremacy.” The term inspires images of a giant world-brain supercomputer that can count the grains of sand on every beach on Earth. But what does Google’s official claim of supremacy mean and how will practical quantum computing change the world of crypto?

After a month of speculation, Google announced that it has built and tested a 54-qubit quantum processor called “Sycamore.” The processor, which looks like it’s covered in a writhing mass of serpents inside its super-cooled cryo-chamber, was able to perform a complex computation in 200 seconds. Not that big a deal, right?

“From measurements in our experiment we determined that it would take the world’s fastest supercomputer 10,000 years to produce a similar output,” wrote Sycamore’s creators in a blog post.

Image via Google.

Quantum processors work by using superposition and entanglement. These odd quantum behaviors essentially allow a quantum chip to process massive amounts of data simultaneously. To better understand it, imagine that, like Dr. Strange, a quantum processor can “see” every possible outcome at once and then, statistically, pick the most likely answer. This means time-consuming programs like factoring large numbers – finding the two large numbers that, when multiplied, makes another large number – is trivial for a quantum computer.

These machines are nothing new. Services like D-Wave’s Leap let anyone write programs for a cloud-based quantum computer in Python, a feat that seems like science fiction. However, in Google’s case, the company has achieved “quantum supremacy” over nearly every other machine in existence – a claim that means, in theory, quite a lot and, in practice, very little.

Quantum supremacy means that Google has been able to perform a calculation that is impossible to perform on traditional computing hardware. In other words, no “classical” computer – from the fastest mainframe to an Atari 800XL – would…

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