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

Google debuted Willow, its newest quantum chip, on Wednesday, and for those who’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 pc chip,” reads another. It’s all anchored by a declare that Willow can full a computation that might theoretically take a classical pc considerably extra time than the 14 billion years the universe has existed. However, as you’ll be able to in all probability guess, what the chip represents shouldn’t be 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 pc, Sycamore, again in 2019. Chances are you’ll recall that, on the time, Google publicized the way it took Sycamore simply 200 seconds to carry out a calculation that might have theoretically taken the world’s then-fastest supercomputer 10,000 years to finish. That feat, the corporate stated, demonstrated that it had created a quantum pc that would resolve issues the very best classical computer systems couldn’t even try. In different phrases, Google had achieved quantum supremacy.

Nonetheless, that declare rapidly led to controversy, with one researcher calling the corporate’s announcement “indefensible” and “simply plain improper,” and Google has since averted 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 pc; 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 functions.” But, right here once more, the corporate is touting RCS efficiency.

Google says Willow can full its newest RCS benchmark in beneath 5 minutes. In contrast, the corporate estimates it could take Frontier, at the moment 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, in keeping with the concept that we dwell 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. Based on Hartmut Neven, the founding father of Google Quantum AI, “it’s an entry level. If you happen to can’t win on random circuit sampling, you’ll be able to’t win on every other algorithm both.” He provides RCS is “now extensively used as a typical within the discipline.“

Nonetheless, 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 brink.” Thus far, the issue that has plagued each try and construct a helpful quantum pc is that the quantum bits they’re based mostly 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 seemingly it’s to provide errors. Nonetheless, with Willow, Google says it has discovered a method to scale back errors because it provides extra qubits to the system. Based on the corporate, Willow is the primary time this has been carried out.

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

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