Monday, November 12, 2007

Google and Quantum Computers


Google scientists to demo quantum computer.

So I thought Google was clever, convention-shattering even. But mind-blowing?

I wrote here about the zombie epitomizing decoherence. To understand the impact of quantum computers (and Google Itself making one), we need to do a little more background discussion.

First, classic physics and quantum mechanics are at odds with each other theoretically. When Richard Feynman and others began discussing quantum mechanics in the 1940s and 50s, Einstein retorted with the famous remark, "God does not play dice with the universe."

Einstein, as do mostly all physicists, believed there was a Grand Unifying Theory. Call it God, A Force, whatever, but it was at work and it controlled everything. To Einstein, this meant there was a logical explanation to the workings of the universe. To other theoretical physicists, many of whom were thrilled by Einstein's theory of relativity, there was certainly a grand scheme, but it was by no means logical.

The difference between classical physics and quantum mechanics can be crudely simplified by the discussion of electrons. In classical physics, electrons occupy levels, which contain pairs of up-spin, down-spin electrons. Here's a crude picture, the arrows representing an electron and the direction of its spin.

But the classical theory of electrons doesn't hold up under close inspection. Instead, it seems as though we can never actually know the direction and the position of an electron simultaneously. This comes from Heisenberg's Uncertainty Principle. Rather than seeing the electron distribution in a deterministic, boxy fashion (like classical physics), quantum mechanics creates probabilistic clouds, shown below.

As molecules get more complicated, electron cloud distributions get more intense, and more beautiful. For example, this molecule's electron cloud distribution looks like a trilobite (source):

So what does this have to do with computers? Well, computers run on binary code. The only two symbols of the binary code is the symbol 1 and the symbol 0. These two symbols represent, roughly, an electron being allowed to pass and an electron not being allowed to pass. The computer recognizes this and translates it into other electronic functions (fire this node, light, whatever). The binary system runs all our computers and it finds its basis from the classical physical approach to electrons. yes/no, 1/0, up-spin/down-spin can all be seen as deterministic.

Quantum computers, however, are probabilistic. This means they work from the assumption (to continue the up-spin, down-spin analogy) that an electron can be spinning up, spinning down, or spinning up and down simultaneously. From the quantum approach, we can never actually know something. We can only be %99.999999(repeating) sure we do. For example, the biggest breakthrough so far in quantum computation was the calculation of 3 and 5 being the only factors of 15 (besides 1 and 15 itself, of course). Although, as a quantum caveat, there's a infinitesimally small probability that actually might not be true.

While this may seem a trivial computation, it means an enormous amount to anyone interested in computers and society. Banks, the veins holding the lifeblood of our vibrant society, protect our money by encryption. The method of encryption is creating an ENORMOUS prime number, then multiplying it by another ENORMOUS prime number. Two agents have two numbers: you have your prime number and the multiple, the bank has the other prime number and the multiple. The only way the bank to know you are you is to show your prime number and the common multiple, which is held conveniently on your bank card. It would take even a supercomputer operating on classical terms perhaps millions of years to factorize the common multiple used in bank encryption. The easier way is theft: either steal the hardware (or your card) or the data itself (online scammers stealing your credit card number).

A basic quantum computer "Could Solve Problems In A Few Months That Would Take Conventional Computers Millions Of Years." Why? Because a quantum computer understanding a probabilistic environment can attempt all passwords simultaneously. Blows your mind, right?

Luckily, the conversation hasn't started about whether the terrorists can get a quantum computer. First, you can't do it in secret. It would be like trying to build another atomic bomb, needing the resources of so many brilliant individuals. And you'd need a lot of money, like your stock would have to be valued at like $632.07 A SHARE.


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