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Has Google achieved quantum supremacy?

Written by Mon 23 Sep 2019

Yes – but it does not spell the end of cryptography, as some have claimed

Google has claimed to have reached a major quantum computing milestone in a research paper that briefly appeared on a NASA website.

In the research paper, spotted by the Financial Times before it was removed, the company claimed to have designed a quantum computer capable of “quantum supremacy.”

Google’s system is capable of proving that a random number generator is truly random. Its processor completed the task in three minutes and twenty seconds. The same task would take Summit, the world’s most powerful supercomputer, roughly 10,000 years to complete.

“To our knowledge, this experiment marks the first computation that can only be performed on a quantum processor,” the research paper reportedly said.

“This dramatic speed-up relative to all known classical algorithms provides an experimental realization of quantum supremacy on a computational task and heralds the advent of a much-anticipated computing paradigm,” it added.

After the news surfaced over the weekend, several commentators weighed in online to explain what the achievement actually meant.

Some have made bombastic claims about the research’s implications for cryptography, a widely-used method of encryption that a sufficiently powerful quantum computer will someday be able to undermine. 2020 US Presidential Candidate Andrew Yang tweeted that the research ‘means among other things, that no code is uncrackable’.

But experts have said this interpretation overstates Google’s achievement and have urged for a more measured analysis.

Greg Meyer, a computing physicist at the University of California Berkeley, tweeted:

“I just wanted to add a quick note. I think it’s important to differentiate between quantum supremacy and quantum advantage. Supremacy: “do any computational task that is hard (provably!) for classical computers” and advantage “do a *useful* task faster.”

Google has not achieved quantum advantage, as the task its system performed was highly technical. Google’s researchers noted it will still take years for its system to support practical (or useful) applications. In other words, Google has not created a system capable of cracking code faster than conventional computers, despite Yang’s bold claims.

Nevertheless, Google has managed to create a processor capable of performing a calculation that a classical computer cannot. Even though Summit could conceivably complete the task in 10,000 years, this represents such a long time to render it an effectively meaningless statement.

Even though Google has not achieved quantum advantage, the research provides another striking demonstration of what gets people excited about quantum computing in the first place: Its ability to solve problems at mind-boggling speeds compared to traditional computing. Despite the highly specific and technical nature of the task it performed, Google’s system still performed it at a fraction of the time it would take the world’s most powerful supercomputer.

Written by Mon 23 Sep 2019


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