Sunday, October 7, 2012

Cold water on quantum hype

Charlie Bennett writes:
Throwing cold water on the Quantum Internet

The most common misconception about entanglement is that it can be used to communicate—transmit information from a sender to a receiver—perhaps even instantaneously. In fact it cannot communicate at all, except when assisted by a classical or quantum channel, neither of which communicate faster than the speed of light. So a future Internet will need wires, radio links, optical fibers, or other kinds of communications links, mostly classical, but also including a few quantum channels.

How soon before the quantum internet could arrive?
I don’t think there will ever be an all-quantum or mostly-quantum internet. Quantum cryptographic systems are already in use in a few places, and I think can fairly be said to have proven potential for improving cybersecurity. Within a few decades I think there will be practical large-scale quantum computers, which will be used to solve some problems intractable on any present or foreseeable classical computer, but they will not replace classical computers for most problems. I think the Internet as a whole will continue to consist mostly of classical computers, communications links, and data storage devices.
He is right that there will never be a quantum internet, but it is not true that quantum cryptographic systems have proven potential for improving cybersecurity. Nobody has ever shown that quantum cryptography has any cybersecurity value at all.

I do not believe that we will see practical large-scale quantum computers either. Others disagree with me, but we are still waiting for a proof of concept that any such computers are possible.

Update: Some are buying into the hype:
Jeff Bezos has put money into a robot factory worker, a 10,000 year clock and private car service. And he’s not done yet.

Bezos Expeditions and In-Q-Tel, the venture arm of the CIA, announced Thursday a $30 million investment in D-Wave Systems, a Vancouver-based company that develops quantum-computing applications.

D-Wave Systems integrates computer science and physics discoveries with new-age computational processes. It’s focused on solving “optimization” problems, like finding out the most efficient delivery routes or how protein atoms interact with drug compounds. Some say the technology is more efficient than classical computing.
D-Wave does not have the qubit computer that everyone wants. I guess they somehow convinced Bezos that they can do some useful computations anyway.

Update: Soott Aaronson writes:
D-Wave still hasn’t demonstrated 2-qubit entanglement, which I see as one of the non-negotiable “sanity checks” for scalable quantum computing. ... Keep in mind that D-Wave has now spent ~$100 million and ~10 years of effort on a highly-optimized, special-purpose computer for solving one specific optimization problem.

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