So the world’s most clandestine spy agency is working on something called a quantum computer, The Washington Post tells us. It’s based on rules Einstein himself described as “spooky,” and it can crack almost any code. That’s got to be top-secret stuff, right?
Guess again. The second physicist I called for today’s story, a guy named Christopher Monroe at the University of Maryland, not only knew the National Security Agency did this research; he had actually worked with the agency.
“It’s all in the open,” he says.
The reasons for trying to build a quantum computer are no secret. Most of the world’s computers encrypt their data using very large numbers. To break the code, spy agencies have to divide the numbers by other numbers — prime numbers. Finding the right prime numbers can take a while.
“A thousand-digit number might take a full year of a team of supercomputers,” says Monroe. “You can add another hundred digits, and forget it — you won’t be able to ever do it.”
That’s where a quantum computer comes in. Most computers work using bits of data — ones and zeros. The bits in quantum computers can be both one and zero at the same time. What’s more, these quantum bits can all be interconnected in a fundamental way. Known as entanglement, this connecting of bits effectively allows the computer to try many numbers at once.
“It can look at them all at the same time and there’s a huge speed-up by doing that,” Monroe says.
A code that was impossible to break could be cracked in weeks, days — maybe even hours. That’s why the NSA needs to pay attention to quantum computers.
“The NSA just wouldn’t be doing their job if they weren’t following it,” says Scott Aaronson, a computer scientist at MIT who specializes in quantum computing.
While the NSA’s interest is clear, the documents leaked by Edward Snowden to the Washington Post seem to indicate that the agency’s progress on a quantum computer is slow. The modest advances described in one area, semiconducting quantum bits, seem to be roughly equal to what’s happening in the open world.
Aaronson’s not surprised. Quantum computers are fragile and very, very difficult to build. It could be decades, or even centuries, before one is fully realized.
The NSA needs to be involved with what scientists are doing, but it doesn’t need to spend billions on a crash program to build a quantum computer. It already has plenty of ways to read people’s emails.
“The NSA has been doing many more low-tech things like giving itself back doors into encryption standards or just strong-arming Google or Microsoft into giving it access to things,” Aaronson says.