The Quantum Computer Bogeyman

Quantum computer, courtesy IBM

Peter Gutmann of the University of Aukland recently published a parable “On the Heffalump Threat.” He pokes fun at the R&D cottage industry trying to achieve a practical quantum computer and at related efforts at “post quantum cryptography.” Security People always like to be prepared, even if the rest of us aren’t.

Here’s the background: A practical (gigantic) quantum computer will threaten our cryptographic systems because there are quantum-style techniques for cracking popular modern ciphers. I remain skeptical.

But, they cry, what about the ongoing announcements about bigger and better quantum computers?

Personally, I suspect there’s a physical limit somewhere in quantum computing technology that prevents us from building gigantic quantum computers. Maybe I’m like the scientists in the 19th century who used existing scientific models to argue against aeroplanes. I think there are intersections of information theory and physics that will make large-scale quantum computing impractical. We can’t really prove how accurately our 21st century models apply to quantum computing. There are gaps in our knowledge that justify research in the area.

Here is Peter’s parable: