Picture, if you can, the following scene. It’s the year 2040. You wake up in the morning, and walk across your bedroom to your computer to check your email and some news websites. Your computer, your mail reader, and your web browser have some new bells and whistles, but all of them would be recognizable to a visitor from 2014: on casual inspection, not that much has changed. But one thing has changed: if, while browsing the web, you suddenly feel the urge to calculate the ground state energy of a complicated biomolecule, or to know the prime factors of a 5000-digit positive integer — and who among us don’t feel those urges, from time to time? — there are now online services that, for a fee, will use a quantum computer to give you the answer much faster than you could’ve obtained it classically. Scientists, you’re vaguely aware, are using the new quantum simulation capability to help them design drugs and high-efficiency solar cells, and to explore the properties of high-temperature superconductors. Does any of this affect your life? Sure, maybe it does — and if not, it might affect your children’s lives, or your grandchildren’s. At any rate, it’s certainly cool to know about. ...So even if scalable quantum computers are invented, the impact on our lives will be negligible.
As magical as it all sounds, this is the wondrous science-fiction future that my sixteen years of research in quantum computing and information lead me to believe is possible. Assuming, of course, that we actually do build scalable quantum computers.
I guess he is being sarcastic here, so it is hard to tell whether he thinks quantum computers will ever be possible, or whether he is making fun of those who do. He alternates between over-hyping the subject, and criticizing those who do.
Predicting the future is tricky, of course, but computer technology has been on a stable predictable path for a long time. Processing power has followed Moore's Law for 50 years. Artificial intelligence, such as voice and image recognition, has progressed more or less on schedule. Some say that we are headed for the Singularity around 2040. That seems optimistic to me, but they are not even assuming quantum computer benefits.
But there is still no experiment demonstrating that quantum computers are feasible, and I doubt that there ever will be.
I agree with Gil Kalai:
I find the article entertaining and enjoyable in spite of me being one of the “skeptics” who think that superior computation through quantum computers is not possible. (And I really mean “not possible” :) .) ... Of course, impossibility of computationally superior quantum computing is not in conflict with quantum mechanics.Even if quantum computers are possible, the main application will be destructive -- breaking our current computer security and requiring complicated and expensive work-arounds to achieve what is easy today.
To be honest, I have no idea whether QKD will ever find a significant market or not. But at least the technology already exists (and “works,” over short enough distances), if a nontrivial market were ever to develop.Quantum key distribution will probably never have any practical utility. Sure it works, but much simpler methods give much better security.
It’s true that there are classical cryptosystems that are probably secure even against quantum computers. However, the trouble is that all such systems currently known are either
(a) private-key, and hence cumbersome to use, or else
(b) public-key systems like the lattice-based systems, which currently require key sizes and message sizes large enough to make them impractical for most applications.
Of course, it’s possible that more practical quantum-secure public-key cryptosystems will eventually be discovered. Certainly lots of people have been thinking about that. But if no such systems are discovered, and if (on the other side) the technology of QKD were to improve so that it could handle much higher bit-rates and distances, then there really could be a good use case for QKD.