Google’s Willow quantum chip breakthrough is hidden behind a questionable benchmark

Google debuted Willow, its newest quantum chip, on Wednesday, and in case you’ve spent any time on-line since, you’ve undoubtedly run into some breathless reporting about it. Willow “crushes classical computer systems on a cosmic timescale,” proclaims one headline; Google “unveils ‘mind-boggling’ quantum laptop chip,” reads another. It’s all anchored by a declare that Willow can full a computation that may theoretically take a classical laptop considerably extra time than the 14 billion years the universe has existed. However, as you possibly can in all probability guess, what the chip represents just isn’t so easy.

First, with Willow, Google makes no declare of quantum supremacy, one thing the corporate did when it publicly debuted its earlier technology quantum laptop, Sycamore, again in 2019. You could recall that, on the time, Google publicized the way it took Sycamore simply 200 seconds to carry out a calculation that may have theoretically taken the world’s then-fastest supercomputer 10,000 years to finish. That feat, the corporate mentioned, demonstrated that it had created a quantum laptop that would clear up issues the perfect classical computer systems couldn’t even try. In different phrases, Google had achieved quantum supremacy.

Nevertheless, that declare rapidly resulted in controversy, with one researcher calling the corporate’s announcement “indefensible” and “simply plain improper,” and Google has since prevented speaking about quantum supremacy. As a substitute, it simply says it has achieved “past classical computation.” A part of the difficulty was that Sycamore was not a general-purpose quantum laptop; as a substitute, it was designed to surpass classical computer systems in a single activity often called random circuit sampling or RCS. The factor about RCS is that, in Google’s personal phrases, it has “no recognized real-world purposes.” But, right here once more, the corporate is touting RCS efficiency.

Google says Willow can full its newest RCS benchmark in below 5 minutes. Against this, the corporate estimates it might take Frontier, presently the world’s second strongest supercomputer, 10 septillion years to finish the identical activity. That quantity, Google says, “lends credence to the notion that quantum computation happens in lots of parallel universes, consistent with the concept that we stay in a multiverse.”

Extra virtually, Google tries to make the case that RCS efficiency must be the metric by which all quantum computer systems are judged. In line with Hartmut Neven, the founding father of Google Quantum AI, “it’s an entry level. Should you can’t win on random circuit sampling, you possibly can’t win on every other algorithm both.” He provides RCS is “now extensively used as a normal within the discipline.“

Nevertheless, different firms, together with IBM and Honeywell, as a substitute use a metric referred to as quantum quantity to tout their breakthroughs. They declare it factors to a extra holistic understanding of a machine’s capabilities by factoring in how its qubits work together with each other. Sadly, you received’t discover any point out of quantum quantity within the spec sheet Google shared for Willow, making comparisons troublesome.

To that time, the way more spectacular declare Google is making right now is that Willow is “beneath the edge.” Up to now, the issue that has plagued each try to construct a helpful quantum laptop is that the quantum bits they’re primarily based on are troublesome to regulate. They solely maintain their quantum state for fractions of a second, and the extra qubits are added to a system, the extra possible it’s to provide errors. Nevertheless, with Willow, Google says it has discovered a approach to scale back errors because it provides extra qubits to the system. In line with the corporate, Willow is the primary time this has been executed.

“As the primary system beneath threshold, that is probably the most convincing prototype for a scalable logical qubit constructed thus far. It’s a robust signal that helpful, very giant quantum computer systems can certainly be constructed,” says Neven. “Willow brings us nearer to operating sensible, commercially-relevant algorithms that may’t be replicated on typical computer systems.”

That’s the true breakthrough right here, and one which factors to a future the place quantum computer systems might clear up issues which have tangible results on folks’s lives. That future, nonetheless, is not right here simply but, and even Google admits it has extra work to do earlier than it will get there.