Scott Aaronson, a computer science professor at the Massachusetts Institute of Technology, gave his views on the future of quantum technology in an interview with The Washington Post. Here are some excerpts:
How long have people been thinking about quantum computation?
The idea of quantum computing was proposed in the 1980s by physicists like Richard Feynman and David Deutsch, but it wasn't obvious that a quantum computer would be good for anything.
The only application people could see immediately was you could use a quantum computer to simulate quantum mechanics. That's sort of obvious.
The big discovery that sort of got people excited about this field was when Peter Shor discovered in  that [if you had a quantum computer], you could use it to find the prime factors of enormous numbers.
That's a practical problem we don't know how to solve with [conventional] computers in any reasonable amount of time.
People care about it because the security of e-commerce is based on the difficulty of finding prime factors. If you can do that you can break most of the cryptography on the internet.
How likely is it that the US National Security Agency has succeeded in creating practical quantum computers?
People have speculated about that possibility. I don't know. I don't have the security clearance. But there are some things that make me think it's not likely.
One of them is that we know who the best experimentalists are, and yes the NSA is interested and talks to them and funds them, but we haven't seen them hoovering them up like the Manhattan Project.
The more important thing is that if your goal is to read people's e-mail, there are so many more straightforward ways to go about that than building a quantum computer. It's an exotic possibility that captures people's imagination, but in reality, when these systems are broken, it's not by bashing down the fortress, it's by finding a back door.
[Edward] Snowden himself said properly implemented strong crypto is one of the things you can rely on.
There are so many more prosaic possibilities I'd want to examine before considering the possibility that the NSA is building a quantum computer.
There's also just that it looks to most of us like [quantum computing is] in a basic research stage.
It doesn't look like it's at the point where people could say: "Here's how much money it would take and here's how many years it would take and we can build a device." We still don't know. We're still just trying to figure out which are the basic architectures.
Maybe in 5 or 10 or 20 years it becomes a question of time and money and manpower and how much do people want this thing. Right now, it's a research question of how do you do it at all.