Quantum processor's prime feat raises security issues

Quantum processor's prime feat raises security issues

Summary: California researchers report a breakthrough with the creation of a solid-state quantum processor that could ultimately have a bearing on future cryptographic techniques.


Researchers in California have designed and built a quantum processor capable of factoring 15 into its primes — with major implications for computer security.

Quantum computing is famous for its potential to obliterate current cryptographic techniques. Much of cryptography today relies on the lack of processing power in classical computers to factor a very large number into its primes. Each factorisation would have to be performed sequentially, and when you are dealing with a sufficiently large number, the calculation becomes all but impossible.

Consider RSA Laboratory's largest published number. This number contains over 600 decimal digits. Factoring it with a classical computer would take longer than the age of the universe. However, quantum computing can in theory get around this obstacle by running all the necessary calculations in parallel. An encryption key would be laid bare in a stroke.

"A quantum computer can solve this problem faster than a classical computer by about 15 orders of magnitude," said Erik Lucero, a former doctoral student at the University of California Santa Barbara, now working at IBM's research labs. "This has widespread effect. A quantum computer will be a game-changer in a lot of ways, and certainly with respect to computer security."

However, making this all work in the real world is not trivial. Quantum computing by its nature is riddled with errors: it is at best probabilistic, and extremely vulnerable to perturbations in the environment.

So much so that it is genuinely impressive that Lucero and other researchers at the University of California Santa Barbara have now demonstrated a processor that can factor a number into its primes – 48 percent of the time.

"Fifteen is a small number, but what's important is we've shown that we can run a version of Peter Shor's prime-factoring algorithm on a solid-state quantum processor. This is really exciting and has never been done before," Lucero notes in the university's announcement.

Andrew Cleland, a professor of physics at UCSB and a collaborator on the experiment, said: "What is important is that the concepts used in factoring this small number remain the same when factoring much larger numbers."

He added: "We just need to scale up the size of this processor to something much larger. This won't be easy, but the path forward is clear."

Topics: Emerging Tech, Security

Lucy Sherriff

About Lucy Sherriff

Lucy Sherriff is a journalist, science geek and general liker of all things techie and clever. In a previous life she put her physics degree to moderately good use by writing about science for that other tech website, The Register. After a bit of a break, it seemed like a good time to start blogging about weird quantum stuff for ZDNet. And so here we are.

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  • I'll believe it when I see it

    Quantum computing keeps making promises but I still don't see any practical results.
    • Practical result?!

      You mean like THIS ARTICLE? It's like you've been shown the first transistor and you're like "I want to see something *practicle*"?! It's right in front of your face!
      • the keyword is 50%

        What this previous commenter meant is that getting the correct result 50% of the time is not sufficient for a real "practical" application. I am sure you would not want this device counting YOUR money.
        • obviously

          quantum computing is not going to be viable for real computers any time remotely soon. but this is still cool as a glimpse of the future.
  • quantum computing

    We are still at the stage where Thomas Edison burned out huge numbers of light bulbs before finding out one that lasted more than seconds. We have a long way to go with quantum computing, and when it is done security will come from isolating the systems.
  • 48% is just fine...

    If a quantum computer can find the prime factors of a large number (not 15...) about half the time, its results could then be checked by a conventional computer. If the conventional computer only needs to check the result, that can be done quite quickly on the conventional computer. And if the Wu Antrum computer is delivering the correct factors half the time, there would be only a one-in-a-million chance of not getting the answer after only twenty interactions...
  • Sigh

    Quantum computers only affect public key ciphers like RSA. They will have little practical effect on block ciphers like AES. I wish the tech media would get this right for once.
  • eleven years, have we quantum factored 21 yet?

    According to Wikipedia IBM used a quantum computer with 7 qubits to factor 15 in 2001, but was this a "real quantum computer" was debatable.

    That debate is now ended, but how many qubits are needed to factor a 600 digit number? Perhaps it'll take longer than the age of the universe to build a computer with that many qubits :)
  • They did It!

    Google, NASA, and the non-profit Universities Space Research Association (USRA) recently announced formation of the Quantum Artificial Intelligence Lab and seeded it with a brand new 512-qubit D-Wave Two quantum computer.
    Logan Cheek