'Quantum Supremacy': Google Scientists Claim System Can Complete Task in 200 Seconds That Would Take Normal Supercomputer 10,000 Years

Google scientists have announced their quantum computer took mere minutes to solve a task that would take even the most powerful traditional supercomputer in the world thousands of years to complete.

This achievement of being able to solve something that a "classical computer" cannot (in a practical timeframe) is known as "quantum supremacy" and it is widely considered to be a significant milestone in the development of quantum computers, although there is still a long way to go before these potentially revolutionary devices become a practical reality.

According to a study published in the journal Nature, the quantum computer completed a specific number-sampling task in 200 seconds that the world's most advanced supercomputer would take 10,000 years to achieve. The paper has finally been made available after being leaked online a month ago.

"This demonstration of quantum supremacy over today's leading classical algorithms on the world's fastest supercomputers is truly a remarkable achievement and a milestone for quantum computing," William Oliver, an MIT computer scientist, who was not involved in the research, wrote in a Nature "News & Views" article. "It experimentally suggests that quantum computers represent a model of computing that is fundamentally different from that of classical computers."

Quantum computers are different from traditional systems in the sense that their design is guided by the bizarre phenomena outlined in quantum mechanics—the physics of the very small.

While traditional computers are based on basic units of information known as "bits"—which can only exist in one of two states (0 and 1)—quantum devices are designed around "qubits." These qubits can exist in states of 0 and 1—and everything in between—simultaneously, enabling each one to perform multiple calculations at the same time, unlike bits which can only handle one calculation at a time.

This ability means that quantum computers have the potential to perform certain tasks much faster than classical computers. However, reaching quantum supremacy requires a stable quantum processor that can keep error rates low while providing enough computational space to execute tasks—something that is very difficult to achieve given the unpredictable nature of quantum phenomena.

However, the Google team, led by John Martinis and Sergio Boixo, managed to achieve quantum supremacy with a quantum computer consisting of 54 qubits—although one qubit failed to work during experiments—that featured special error-correcting processes.

Their device exploits two principles in quantum mechanics known as superposition and entanglement—a mind-boggling physical phenomenon in which pairs or groups of tiny particles interact with each other in such a way that they can no longer be described independently, even if they are separated by vast distances—such as being on opposite sides of the universe, for example.

Google headquarters
Close-up of sign and logo at the Googleplex, the Silicon Valley headquarters of search engine and technology company Google Inc. in Mountain View, California, April 14, 2018. Smith Collection/Gado/Getty Image

Despite the significance of the latest findings, Oliver argues that more research needs to be conducted in order to make quantum computers a practical reality.

"In particular, algorithms will have to be developed that can be commercialized and operate on the error-prone intermediate-scale quantum processors that will be available in the near term," he wrote. "And researchers will need to demonstrate robust protocols for quantum error correction that will enable sustained, fault-tolerant operation in the longer term."

"[The] demonstration is in many ways reminiscent of the Wright brothers' first flights. Their airplane, the Wright Flyer, wasn't the first airborne vehicle to fly, and it didn't solve any pressing transport problem," he wrote. "Nor did it herald the widespread adoption of planes or mark the beginning of the end for other modes of transport. Instead, the event is remembered for having shown a new operational regime—the self-propelled flight of an aircraft that was heavier than air. It is what the event represented, rather than what it practically accomplished, that was paramount. And so it is with this first report of quantum computational supremacy."

Some have been quick to cast doubt on the latest achievement, however. Information technology company IBM—the developer of the current fastest classical supercomputer, Summit—has claimed that Google hasn't met the threshold for quantum supremacy, Science magazine reported. IBM says that by slightly adjusting how Summit tackles the same number-sampling task given to Google's quantum device, their traditional supercomputer could complete it in two-and-a-half days, not 10,000 years.

"It is inevitable that better classical algorithms will be identified, and this scrutiny is good; it's part of the scientific process," Oliver told Newsweek. "However, it's important not to lose sight of the fact that nascent quantum processors have matured to the point that we can debate whether a 53-qubit quantum processor performs a particular task in any comparable way to the most powerful classical computers on earth featuring tens of thousands of CPUs and GPUs, trillions of transistors, and 250 petabytes of memory."

This article was updated to include additional comments from William Oliver.